The most frequent side effects associated with Actimmune (interferon gamma 1b) therapy are the occurrence of 'flu-like symptoms' (FLS),which might include fever, chills, muscle aches, and tiredness. Earlier studies have demonstrated that these symptoms are common in healthy volunteers as well as in patients.

This study is designed to determine whether a titration of dosing reduces the frequency and severity of the FLS. A reported study with another interferon (interferon beta), demonstrated a reduction in the frequency and severity of the FLS when a titration of dosing was used. This study will compare the effects of the standard dose regimen with a titration regimen in healthy volunteers.

Inclusion Criteria:

• Healthy volunteers
• Ability to understand purpose & risks
• BMI 18-32kg/m2
• Females on contraception

Exclusion Criteria:

• History of HIV,or pos test for HCV Ab,or HBsAg
• History of chronic fatigue syndrome or fibromyalgia
• Flu like illness within 1 month of start
• History of depression or other mood disorder
• History of malignant or pre-malignant disease
• History of severe allergic reactions
• Known allergy to Actimmune or its components
• History of major diseases
• Clinically Significant abnormal labs
• Pregnant or breastfeeding
• Clinically abnormal ECG
• History of alcohol or substance abuse
• Other study participation in last 4 weeks
• Serious infection within 3 months
• Use of Rx products within 4 weeks except contraceptives or dermatology products
• Vaccinations within 2 weeks
• Tobacco products ( with limitations)
• Cant/wont comply with study requirements
• Allergy shots within 1 month
• Blood donation with limitations
• Investigator discretion as to unsuitability