Part A will comprise of 4 TPs. The subjects in this cohort will receive matching Placebo solution to the study drug GSK3358699 solution for 1 mg and a matching placebo capsule to the study drug GSK3358699, 10 mg and 35 mg capsule, during TP (1 to 3). Each TP will be of 1 day and separated by a washout Period of 14-days. Post completion of the dose-escalation TPs, an additional dosing TP 4 will be included where the subjects from each TP (1 to 3), will receive control blisters induced on forearm (0.2 % cantharidin) at Day -10. The subjects in cohort 1 will receive Placebo at a dose level already given in TP 1-3, and will then receive an intravenous in vivo LPS challenge at a dose not exceeding 0.75 nanogram per kilogram post administration of Placebo. The subjects will then have blisters induced on the forearm approximately 20 minutes after the challenge. LPS dose will be based on data of study 207654 (NCT03306589).

Part A will comprise of 4 TPs. The subjects in this cohort will receive matching Placebo solution to the study drug GSK3358699 solution for 3 mg and a matching placebo capsule to the study drug GSK3358699, for 20 and 45 mg capsule, during TP (1 to 3). Each TP will be of 1 day and separated by a washout Period of 14-days. Post completion of the dose-escalation TPs, an additional dosing TP 4 will be included where the subjects from each TP (1 to 3), will receive control blisters induced on forearm (0.2 % cantharidin) at Day -10. The subjects in cohort 2 will receive Placebo at a dose level already given in TP 1-3, and will then receive 60 microgram per meter^2 of in vivo GM CSF challenge as an intravenous infusion during TP 4, post administration of Placebo. The subjects will then have blisters induced on the forearm approximately 20 minutes after the challenge GM-CSF infusion. GM-CSF dose will be based on data of study 207654 (NCT03306589).

The subjects in this arm will receive single oral dose of GSK3358699, at a dose level evaluated in Part A, under fasted condition in TP1 followed by fed condition in TP2. This cohort intended to evaluate the effect of food.

The subjects in this arm will receive single oral dose of GSK3358699, at a dose level evaluated in Part A, under fed condition in TP1 followed by fasted condition in TP2. This cohort intended to evaluate the effect of food.

The dose level for the first cohort in Part C will be decided following completion of Part A of the study for GSK3358699. The subjects in this arm will constitute 3 cohorts each (cohort 4 to 6), where the subjects will receive GSK3358699, as one repeat dose treatment once daily for 14-consecutive days. Subjects will have control blisters induced on the forearm (0.2% cantharidin) on Day -10. On the Day 14 of each cohort, each subject will receive an intravenous in vivo LPS challenge at a dose not exceeding 0.75 nanogram per kilogram or an intravenous infusion of GM-CSF, in vivo as 60 microgram per meter^2. The administration of LPS or GM CSF will be followed by blister induction on forearm (0.2 % cantharidin).

The subjects in this cohort will receive a matching placebo to GSK3358699, Part C, as a single oral dose once daily for 14 consecutive days. The subjects in this arm will constitute 3 cohorts each (cohort 4 to 6), where the subjects will receive placebo, as one repeat dose treatment once daily for 14-consecutive days. Subjects will have control blisters induced on the forearm (0.2% cantharidin) on Day -10. On the Day 14 of each cohort, each subject will receive an intravenous in vivo LPS challenge at a dose not exceeding 0.75 nanogram per kilogram or an intravenous infusion of GM-CSF, in vivo as 60 microgram per meter^2. The administration of LPS or GM CSF will be followed by blister induction on forearm (0.2 % cantharidin).

GSK3358699, will be administered from 1 mg to 45 mg as an oral solution (1 to 10 mg) or as a capsule (3 to 45 mg), in Part A, B and Part C once daily.

The GM-CSF will be administered as an intravenous infusion to subjects as 60 microgram per meter^2 in Part A (Day 1) and Part C (Day 14).This will be administered for 2 hours approximately, no later than 24 hours post -dose of the GSK3358699 or placebo in Part C

LPS will be administered as an intravenous injection to subjects not exceeding 0.75 nanogram per kilogram in Part A (Day 1) and Part C (Day 14). This will be administered no later than 24 hours post -dose of the GSK3358699 or placebo in Part C.

This will be applied as a topical application with 0.7% cantharidin liquid which will be diluted with acetone to 0.2%.

Blood samples were collected for analysis of clinical chemistry parameters. PCI ranges were <30 grams per liter (g/L) (albumin), <2 or >2.75 millimoles/L (mmol/L) (calcium), >1.3* upper limit of normal (ULN) mmol/L (creatinine), <3 or >9 mmol/L (glucose), <3 or >5.5 mmol/L (potassium), and <130 or >150 mmol/L (sodium). Participants were counted in worst case category that their value changes to (low, within range or no change or high), unless there is no change in their category. Participants whose laboratory value category was unchanged (e.g., High to High), or whose value became within range, were recorded in To within Range or No Change (NC) category. Participants were counted twice if participant had values that changed To Low and To High, so the percentages may not add to 100%.

Clinical chemistry parameters assessed were alanine aminotransferase(ALT)(<10 or >50 international units per liter[IU/L]),alkaline phosphatase(ALP)(<40 or >129 IU/L),aspartate aminotransferase(AST)(<0 or >37 IU/L),cholesterol(<2.3 or >4.9 mmol/L),direct bilirubin(DB)(<0 or >5 micromoles[mcmol]/L),high density lipoprotein (DL)(<0.9 or >1.5 mmol/L),C-reactive protein(CRP)(<0.0 or >5.0mg/liter),low DL(<0 or >3.0 mmol/L), total bilirubin (<0 or >20 mcmol/L),total protein(<63 or >83 grams/L),triglycerides(<0 or >2.3 mmol/L) and blood urea nitrogen(BUN)(<4.76 or >23.24 mg/deciliter).Participants were counted in worst case category that their value changes to (low, normal or high), unless there is NC in their category.Participants whose laboratory value category was unchanged(e.g.,High to High) or whose value became normal, are recorded in "To Normal or NC" category.Participants were counted twice if participant had values that changed To Low and To High, so percentages may not add to 100%.

Blood samples were planned to be collected to analyze the chemistry parameters.

Blood samples were planned to be collected to analyze the chemistry parameters.

Blood samples were collected for analysis of chemistry parameters. PCI ranges were <30 g/L (albumin), <2 or >2.75 mmol/L (calcium), >1.3* ULN mmol/L (creatinine), <3 or >9 mmol/L (glucose), <3 or >5.5 mmol/L (potassium), and <130 or >150 mmol/L (sodium). Participants were counted in worst case category that their value changes to (low, within range or no change or high), unless there is no change in their category. Participants whose laboratory value category was unchanged (e.g., High to High), or whose value became within range, were recorded in To within Range or No Change category. Participants were counted twice if participant had values that changed To Low and To High, so the percentages may not add to 100%.

Clinical chemistry parameters assessed were ALT (<10 or >50 IU/L), ALP (<40 or >129 IU/L), AST (<0 or >37 IU/L), cholesterol (<2.3 or >4.9 mmol/L), DB (<0 or >5 mcmol/L), high DL (<0.9 or >1.5 mmol/L), CRP (<0.0 or >5.0 mg/liter), low DL (<0 or >3.0 mmol/L), total bilirubin (<0 or >20 mcmol/L), total protein (<63 or >83 grams/L), triglycerides (<0 or >2.3 mmol/L) and BUN (<4.76 or >23.24 mg/deciliter). Participants were counted in worst case category that their value changes to (low, normal or high), unless there is NC in their category. Participants whose laboratory value category was unchanged (e.g., High to High) or whose value became normal, are recorded in "To Normal or NC" category. Participants were counted twice if participant had values that changed To Low and To High, so percentages may not add to 100%.

Blood samples collected for analysis of hematology parameters. PCI ranges were >0.54 proportion of red blood cells in blood (hematocrit), >180 grams/liter (hemoglobin), <0.8 *10^9 cells/L (lymphocyte count), <1.5 *10^9 cells/L (total absolute neutrophil count [ANC]), <100 or >550 *10^9 cells/L (platelet count), and <3 or >20*10^9 cells/L (white blood cell [WBC] count). Participants were counted in worst case category that their value changes to (low, within range or no change or high), unless there is no change in their category. Participants whose laboratory value category was unchanged (e.g., High to High), or whose value became within range, were recorded in To within Range or No Change category. Participants were counted twice if the participant had values that changed To Low and To High, so the percentages may not add to 100%.

Hematology parameters assessed were activated partial thromboplastin time (APTT) (<25 or >37 seconds), basophil count (<0.0 or >0.1*10^9 cells/L), eosinophil count (<0.0 or >0.4*10^9 cells/L), fibrinogen (<1.5 or >4.0 g/L), mean corpuscle hemoglobin (MCH) (<26.0 or >33.5 picogram), mean corpuscle volume (MCV) (<80 or >99 femtoliter), monocyte count (<0.2 or >1.0*10^9 cells/L), prothrombin time (PT) (<10 or >12 seconds), red blood cell (RBC) count (<4.4 or >5.8*10^12 cells/L) and reticulocyte count (<0.38 or >2.64 percentage of reticulocytes). Participants were counted in worst case category that their value changes to (low, normal or high), unless there is NC in their category. Participants whose laboratory value category was unchanged (e.g., High to High) or whose value became normal, are recorded in "To Normal or NC" category. Participants were counted twice if participant had values that changed To Low and To High, so percentages may not add to 100%.

Blood samples were planned to be collected to analyze hematology parameters.

Blood samples were planned to be collected to analyze hematology parameters.

Blood samples were collected for analysis of hematology parameters. PCI ranges were >0.54 proportion of red blood cells in blood (hematocrit), >180 grams/liter (hemoglobin), <0.8*10^9 cells/L (lymphocyte count), <1.5*10^9 cells/L (total ANC), <100 or >550*10^9 cells/L (platelet count), and <3 or >20*10^9 cells/L (WBC count). Participants were counted in worst case category that their value changes to (low, within range or no change or high), unless there is no change in their category. Participants whose laboratory value category was unchanged (e.g., High to High), or whose value became within range, were recorded in To within Range or No Change category. Participants were counted twice if the participant had values that changed To Low and To High, so the percentages may not add to 100%.

Hematology parameters assessed were APTT (<25 or >37 seconds), basophil count (<0.0 or >0.1*10^9 cells/L), eosinophil count (<0.0 or >0.4*10^9 cells/L), fibrinogen (<1.5 or >4.0 g/L), MCH (<26.0 or >33.5 picogram), MCV (<80 or >99 femtoliter), monocyte count (<0.2 or >1.0*10^9 cells/L), PT (<10 or >12 seconds), RBC count (<4.4 or >5.8*10^12 cells/L) and reticulocyte count (<0.38 or >2.64 percentage of reticulocytes). Participants were counted in worst case category that their value changes to (low, normal or high), unless there is NC in their category. Participants whose laboratory value category was unchanged (e.g., High to High) or whose value became normal, are recorded in "To Normal or NC" category. Participants were counted twice if participant had values that changed To Low and To High, so percentages may not add to 100%.

Urine samples were collected from participants for analyzing the following urine parameters: potential of hydrogen (pH) and glucose, protein, blood, ketones, bilirubin, urobilinogen, nitrite, leukocytes levels by dipstick. Urine samples showing any abnormality were sent for microscopic examination to detect the presence of RBC, WBC, cellular casts, granular casts, hyaline casts, and were counted as cells per high-power field (cells/HPF). Number of participants with abnormal urinalysis result by microscopic examination have been presented.

Urine samples were planned to be collected to analyze urine parameters.

Urine samples were collected from participants for analyzing the following urine parameters: pH and glucose, protein, blood, ketones, bilirubin, urobilinogen, nitrite, leukocytes levels by dipstick. Urine samples showing any abnormality were sent for microscopic examination to detect the presence of RBC, WBC, cellular casts, granular casts, hyaline casts, and were counted as cells/HPF. Number of participants with abnormal urinalysis result by microscopic examination have been presented.

Vital signs included systolic blood pressure(SBP), diastolic blood pressure(DBP), heart rate, respiratory rate and body temperature and were measured in a semi-supine position after 5 minutes rest. PCI ranges were, SBP (millimeters of mercury [mmHg]): <85 (low) or >160 (high), DBP (mmHg): <45 (low) or >100 (high), heart rate (beats per minute): <40 (low) or >110 (high), respiration rate (breaths per minute): <11(low) or >20(high) and body temperature (degrees Celsius) <35.5 (low) or >38.0 (high). Participants were counted in the worst case category that their value changes to (low, within range or no change, or high), unless there is no change in their category. Participants whose vital signs value category was unchanged (e.g., High to High), or whose value became within range, were recorded in the "To within Range or No Change" category. Participants were counted twice if the participant had values that changed "To Low" and "To High", so the percentages may not add to 100%.

Vital signs were planned to be measured in a semi-supine position after 5 minutes of rest.

Vital signs included SBP, DBP, heart rate, respiratory rate and body temperature and were measured in a semi-supine position after 5 minutes rest. PCI ranges were, SBP (mmHg): <85 (low) or >160 (high), DBP (mmHg): <45 (low) or >100 (high), heart rate (beats per minute): <40 (low) or >110 (high), respiration rate (breaths per minute): <11 (low) or >20 (high) and body temperature (degrees Celsius) <35.5 (low) or >38.0 (high). Participants were counted in the worst case category that their value changes to (low, within range or no change, or high), unless there is no change in their category. Participants whose vital signs value category was unchanged (e.g., High to High), or whose value became within range, were recorded in the "To within Range or No Change" category. Participants were counted twice if the participant had values that changed "To Low" and "To High", so the percentages may not add to 100%.

Twelve lead ECGs were obtained using an ECG machine that automatically calculated the heart rate and measured PR, QRS, QT, and QT interval corrected using the Fridericia's formula (QTcF) intervals. Abnormal findings were categorized as clinically significant (CS) and not clinically significant (NCS). Clinically significant abnormal findings are those which are not associated with the underlying disease, unless judged by the investigator to be more severe than expected for the participant's condition. Data for number of participants with worst case post-Baseline abnormal ECG findings have been presented.

Twelve lead ECGs were planned to be performed to measure PR interval, QRS duration, QT interval and QTcF.

Twelve lead ECGs were obtained using an ECG machine that automatically calculated the heart rate and measured PR, QRS, QT, and QTcF intervals. Abnormal findings were categorized as clinically significant and not clinically significant. Clinically significant abnormal findings are those which are not associated with the underlying disease, unless judged by the investigator to be more severe than expected for the participant's condition. Data for number of participants with worst case post-Baseline abnormal ECG findings have been presented.

Blood samples were planned to be collected at indicated time points for pharmacokinetic analysis of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3358699. PK parameters were calculated using standard non-compartmental analysis.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3358699. PK parameters were calculated using standard non-compartmental analysis.

Blood samples were planned to be collected at indicated time points for pharmacokinetic analysis of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3358699. PK parameters were calculated using standard non-compartmental analysis.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3358699. PK parameters were calculated using standard non-compartmental analysis.

Blood samples were planned to be collected at indicated time points for pharmacokinetic analysis of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3358699. PK parameters were calculated using standard non-compartmental analysis.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3358699. PK parameters were calculated using standard non-compartmental analysis.

Blood samples were planned to be collected at indicated time points for pharmacokinetic analysis of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3358699. PK parameters were calculated using standard non-compartmental analysis.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3358699. PK parameters were calculated using standard non-compartmental analysis.

Blood samples were planned to be collected at indicated time points for pharmacokinetic analysis of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3358699. PK parameters were calculated using standard non-compartmental analysis.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3358699. PK parameters were calculated using standard non-compartmental analysis.

Blood samples were planned to be collected at indicated time points for pharmacokinetic analysis of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3358699. PK parameters were calculated using standard non-compartmental analysis.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3358699. PK parameters were calculated using standard non-compartmental analysis.

Blood samples were planned to be collected at indicated time points for pharmacokinetic analysis of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3358699. PK parameters were calculated using standard non-compartmental analysis.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3206944. PK parameters were calculated using standard non-compartmental analysis. GSK3206944 is a metabolite of GSK3358699.

Blood samples were planned to be collected at indicated time points for pharmacokinetic analysis of GSK3206944. GSK3206944 is a metabolite of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3206944. PK parameters were calculated using standard non-compartmental analysis. GSK3206944 is a metabolite of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3206944. PK parameters were calculated using standard non-compartmental analysis. GSK3206944 is a metabolite of GSK3358699.

Blood samples were planned to be collected at indicated time points for pharmacokinetic analysis of GSK3206944. GSK3206944 is a metabolite of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3206944. PK parameters were calculated using standard non-compartmental analysis. GSK3206944 is a metabolite of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3206944. PK parameters were calculated using standard non-compartmental analysis. GSK3206944 is a metabolite of GSK3358699.

Blood samples were planned to be collected at indicated time points for pharmacokinetic analysis of GSK3206944. GSK3206944 is a metabolite of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3206944. PK parameters were calculated using standard non-compartmental analysis. GSK3206944 is a metabolite of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3206944. PK parameters were calculated using standard non-compartmental analysis. GSK3206944 is a metabolite of GSK3358699.

Blood samples were planned to be collected at indicated time points for pharmacokinetic analysis of GSK3206944. GSK3206944 is a metabolite of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3206944. PK parameters were calculated using standard non-compartmental analysis. GSK3206944 is a metabolite of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3206944. PK parameters were calculated using standard non-compartmental analysis. GSK3206944 is a metabolite of GSK3358699.

Blood samples were planned to be collected at indicated time points for pharmacokinetic analysis of GSK3206944. GSK3206944 is a metabolite of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3206944. PK parameters were calculated using standard non-compartmental analysis. GSK3206944 is a metabolite of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3206944. PK parameters were calculated using standard non-compartmental analysis. GSK3206944 is a metabolite of GSK3358699.

Blood samples were planned to be collected at indicated time points for pharmacokinetic analysis of GSK3206944. GSK3206944 is a metabolite of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3206944. PK parameters were calculated using standard non-compartmental analysis. GSK3206944 is a metabolite of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3206944. PK parameters were calculated using standard non-compartmental analysis. GSK3206944 is a metabolite of GSK3358699.

Blood samples were planned to be collected at indicated time points for pharmacokinetic analysis of GSK3206944. GSK3206944 is a metabolite of GSK3358699.

Blood samples were collected at indicated time points for pharmacokinetic analysis of GSK3206944. PK parameters were calculated using standard non-compartmental analysis. GSK3206944 is a metabolite of GSK3358699.

Blood samples were collected into sodium heparin tubes for the isolation of monocytes and for measurement of GSK3206944 concentrations in monocytes. GSK3206944 is a metabolite of GSK3358699.

Blood samples were planned to be collected into sodium heparin tubes for the isolation of monocytes and for measurement of GSK3206944 concentrations in monocytes. GSK3206944 is a metabolite of GSK3358699.

Blood samples were collected into sodium heparin tubes for the isolation of monocytes and for measurement of GSK3206944 concentrations in monocytes. GSK3206944 is a metabolite of GSK3358699.

Whole blood samples of 1 milliliter (mL) were collected in TruCulture tubes, containing LPS and incubated for 24 hours, post which the inflammatory mediators (MCP-1, IL-6 and TNF alpha) were analyzed.

Whole blood samples were planned to be collected in TruCulture tubes, containing LPS and incubated for 24 hours, post which the inflammatory mediators (MCP-1, IL6 and TNF alpha) were planned to be analyzed.

Whole blood samples of 1 mL were collected in TruCulture tubes, containing LPS and incubated for 24 hours, post which the inflammatory mediators (MCP-1, IL-6 and TNF alpha) were analyzed.

Participants in Part A Cohort 1 received a SD of placebo (Treatment P) on Day 1 in treatment Period 1; followed by a SD of GSK3358699 10 mg (Treatment C) on Day 1 in treatment Period 2; followed by a SD of GSK3358699 40 mg (Treatment E) on Day 1 in treatment Period 3. On Day 1 of treatment Period 4, participants were administered a SD of GSK3358699 25 mg (Treatment R) followed by IV administration of in vivo LPS challenge at a dose of 0.75 ng/kg and further treated with 0.2% cantharidin for induction of blisters on the forearm. GSK3358699 and placebo were administered via the oral route. There was a washout period of 14 days between each treatment period.

Participants in Part A Cohort 1 received a SD of GSK3358699 1 mg (Treatment A) on Day 1 in treatment Period 1; followed by a SD of placebo (Treatment P) on Day 1 in treatment Period 2; followed by a SD of GSK3358699 40 mg (Treatment E) on Day 1 in treatment Period 3. On Day 1 of treatment Period 4, participants were administered a SD of placebo (Treatment P) followed by IV administration of in vivo LPS challenge at a dose of 0.75 ng/kg and further treated with 0.2% cantharidin for induction of blisters on the forearm. GSK3358699 and placebo were administered via the oral route. There was a washout period of 14 days between each treatment period.

Participants in Part A Cohort 1 received a SD of GSK3358699 1 mg (Treatment A) on Day 1 in treatment Period 1; followed by a SD of placebo (Treatment P) on Day 1 in treatment Period 2; followed by a SD of GSK3358699 40 mg (Treatment E) on Day 1 in treatment Period 3. On Day 1 of treatment Period 4, participants were administered a SD of GSK3358699 25 mg (Treatment R) followed by IV administration of in vivo LPS challenge at a dose of 0.75 ng/kg and further treated with 0.2% cantharidin for induction of blisters on the forearm. GSK3358699 and placebo were administered via the oral route. There was a washout period of 14 days between each treatment period.

Participants in Part A Cohort 1 received a SD of GSK3358699 1 mg (Treatment A) on Day 1 in treatment Period 1; followed by a SD of GSK3358699 10 mg (Treatment C) on Day 1 in treatment Period 2; followed by a SD of placebo (Treatment P) on Day 1 in treatment Period 3. On Day 1 of treatment Period 4, participants were administered a SD of placebo (Treatment P) followed by IV administration of in vivo LPS challenge at a dose of 0.75 ng/kg and further treated with 0.2% cantharidin for induction of blisters on the forearm. GSK3358699 and placebo were administered via the oral route. There was a washout period of 14 days between each treatment period.

Participants in Part A Cohort 1 received a SD of GSK3358699 1 mg (Treatment A) on Day 1 in treatment Period 1; followed by a SD of GSK3358699 10 mg (Treatment C) on Day 1 in treatment Period 2; followed by a SD of placebo (Treatment P) on Day 1 in treatment Period 3. On Day 1 of treatment Period 4, participants were administered a SD of GSK3358699 25 mg (Treatment R) followed by IV administration of in vivo LPS challenge at a dose of 0.75 ng/kg and further treated with 0.2% cantharidin for induction of blisters on the forearm. GSK3358699 and placebo were administered via the oral route. There was a washout period of 14 days between each treatment period.

Participants in Part A Cohort 2 received a SD of placebo (Treatment P) on Day 1 in treatment Period 1; followed by a SD of GSK3358699 20 mg (Treatment D) on Day 1 in treatment Period 2; followed by a SD of GSK3358699 30 mg (Treatment F) on Day 1 in treatment Period 3. On Day 1 of treatment Period 4, participants were administered a SD of placebo (Treatment P) followed by IV administration of in vivo administration of Granulocyte-Macrophage Colony-Stimulating Factor (GM-CSF) at a dose of 60 micrograms per meter square (mcg/m^2) and further treated with 0.2% cantharidin for induction of blisters on the forearm. GSK3358699 and placebo were administered via the oral route. There was a washout period of 14 days between each treatment period.

Participants in Part A Cohort 2 received a SD of placebo (Treatment P) on Day 1 in treatment Period 1; followed by a SD of GSK3358699 20 mg (Treatment D) on Day 1 in treatment Period 2; followed by a SD of GSK3358699 30 mg (Treatment F) on Day 1 in treatment Period 3. On Day 1 of treatment Period 4, participants were administered a SD of GSK3358699 25 mg (Treatment R) followed by IV administration of in vivo administration of GM-CSF at a dose of 60 mcg/m^2 and further treated with 0.2% cantharidin for induction of blisters on the forearm. GSK3358699 and placebo were administered via the oral route. There was a washout period of 14 days between each treatment period.

Participants in Part A Cohort 2 received a SD of GSK3358699 3 mg (Treatment B) on Day 1 in treatment Period 1; followed by a SD of placebo (Treatment P) on Day 1 in treatment Period 2; followed by a SD of GSK3358699 30 mg (Treatment F) on Day 1 in treatment Period 3. On Day 1 of treatment Period 4, participants were administered a SD of placebo (Treatment P) followed by IV administration of in vivo administration of GM-CSF at a dose of 60 mcg/m^2 and further treated with 0.2% cantharidin for induction of blisters on the forearm. GSK3358699 and placebo were administered via the oral route. There was a washout period of 14 days between each treatment period.

Participants in Part A Cohort 2 were planned to receive a SD of GSK3358699 3 mg (Treatment B) on Day 1 in treatment Period 1.Participants were received a SD of placebo (Treatment P) on Day 1 in treatment Period 2; followed by a SD of GSK3358699 30 mg (Treatment F) on Day 1 in treatment Period 3. On Day 1 of treatment Period 4, participants were administered a SD of GSK3358699 25 mg (Treatment R) followed by IV administration of in vivo administration of GM-CSF at a dose of 60 mcg/m^2 and further treated with 0.2% cantharidin for induction of blisters on the forearm. GSK3358699 and placebo were administered via the oral route. There was a washout period of 14 days between each treatment period.

Participants in Part A Cohort 2 received a SD of GSK3358699 3 mg (Treatment B) on Day 1 in treatment Period 1; followed by a SD of GSK3358699 20 mg (Treatment D) on Day 1 in treatment Period 2; followed by a SD of placebo (Treatment P) on Day 1 in treatment Period 3. On Day 1 of treatment Period 4, participants were administered a SD of placebo (Treatment P) followed by IV administration of in vivo administration of GM-CSF at a dose of 60 mcg/m^2 and further treated with 0.2% cantharidin for induction of blisters on the forearm. GSK3358699 and placebo were administered via the oral route. There was a washout period of 14 days between each treatment period.

Participants in Part A Cohort 2 received a SD of GSK3358699 3 mg (Treatment B) on Day 1 in treatment Period 1; followed by a SD of GSK3358699 20 mg (Treatment D) on Day 1 in treatment Period 2; followed by a SD of placebo (Treatment P) on Day 1 in treatment Period 3. On Day 1 of treatment Period 4, participants were administered a SD of GSK3358699 25 mg (Treatment R) followed by IV administration of in vivo administration of GM-CSF at a dose of 60 mcg/m^2 and further treated with 0.2% cantharidin for induction of blisters on the forearm. GSK3358699 and placebo were administered via the oral route. There was a washout period of 14 days between each treatment period.

Participants in Part B Cohort 3 were planned to receive a SD of GSK3358699 under fed conditions on Day 1 in treatment Period 1; followed by a SD of GSK3358699 under fasted conditions on Day 1 in treatment Period 2. There was a planned washout period of 14 days between each treatment period.

Participants in Part B Cohort 3 were planned to receive a SD of GSK3358699 under fasted conditions on Day 1 in treatment Period 1; followed by a SD of GSK3358699 under fed conditions on Day 1 in treatment Period 2. There was a planned washout period of 14 days between each treatment period.

Participants received once daily repeat dose (RD) of placebo on Days 1 to 14. In Cohort 4, on Day 14, participants were administered an IV in vivo LPS challenge at a dose of 0.75 ng/kg or an IV infusion of GM-CSF, in vivo at a dose of 60 mcg/m^2. The administration of LPS or GM-CSF was followed by blister induction on forearm (0.2% cantharidin).

Participants received once daily repeat dose of GSK3358699 10 mg on Days 1 to 14. In Cohort 4, on Day 14, participants were administered an IV in vivo LPS challenge at a dose of 0.75 ng/kg or an IV infusion of GM-CSF, in vivo at a dose of 60 mcg/m^2. The administration of LPS or GM-CSF was followed by blister induction on forearm (0.2% cantharidin).

Participants in Part C Cohort 6 were planned to receive once daily repeat dose of GSK3358699 or placebo on Days 1 to 14.

Participants in Part C Cohort 7 were planned to receive once daily repeat dose of GSK3358699 or placebo on Days 1 to 14.

Participants in Part C Cohort 8 were planned to receive once daily repeat dose of GSK3358699 or placebo on Days 1 to 14. On Day 14, participants were planned to receive an IV in vivo LPS challenge at a dose of 0.75 ng/kg or an IV infusion of GM-CSF, in vivo as 60 mcg/m^2. The administration of LPS or GM-CSF was planned to be followed by blister induction on forearm (0.2% cantharidin).