In this study, lymph fluid will be collected by cannulation of the thoracic duct, a minimally invasive procedure performed by interventional radiologists. Single time point and serial collection through an indwelling cannula will allow for comparisons between immune cells in the periphery and deep lymphatic system in MS and healthy controls and in MS, changes in responses to a FDA approved therapy ofatumumab.

Inclusion Criteria:

• Participants eligible for inclusion in this study must meet all of the following criteria:

  1. Written informed consent must be obtained before any assessment is performed.
  2. Adult participants aged 18 to 40 years (inclusive) at Screening.
  3. Participants must be able to understand English and be able to review and comprehend the informed consent form independently or with the help of research staff
  4. No use of systemic glucocorticoids in the past 4 weeks

For participants with MS following additional criteria need to be met:

1. Diagnosis of MS according to the 2017 Revised McDonald criteria.
2. Ability to undergo several MRIs
3. Disability status at Screening with an EDSS score of 0 to 4 (inclusive)
4. MS treatment history restricted to Interferons and/glatiramer acetate treatment only or untreated to date
5. Neurologically stable within one month prior to interventional procedure.

Exclusion Criteria:

• 1. Participants suspected of not being able or willing to cooperate or comply with study protocol requirements in the opinion of the investigator.

  2. Participants with primary progressive MS (Polman C et al., 2011) 3. Participants meeting criteria for neuromyelitis optica (Wingerchuck D et al., 2015) 4. Participants with disease duration of more than 10 years 5. Participants who are pregnant or nursing (lactating) 6. Participants with active chronic disease (or stable but treated with immune therapy) of the immune system other than MS (e.g. rheumatoid arthritis, scleroderma, Sjögren's syndrome, Crohn's disease, ulcerative colitis, etc.) or with immunodeficiency syndrome (hereditary immune deficiency, drug-induced immune deficiency) 7. Participants with active systemic bacterial, viral or fungal infections, or known to have acquired immunodeficiency syndrome (AIDS) 8. Participants with neurological symptoms consistent with PML or confirmed PML 9. Participants at risk of developing or having reactivation of syphilis or tuberculosis 10. History of cardiovascular disease or uncontrolled hypertension 11. History of diabetes mellitus 12. History of cancer (other than localized skin cancer) in the previous 5 years 13. Have received any live or live-attenuated vaccines (including for varicella-zoster virus or measles) within 2 months prior to first study drug administration 14. Immunization with non-live vaccines within 2 weeks of the study procedure 15. Participants at risk of developing or having reactivation of hepatitis: Positive results at Screening for serological markers for hepatitis (H) B and C indicating acute or chronic infection:

  1. HBs Ag and/or anti-HBc IgM and/or HB virus deoxyribonucleic acid (DNA)
  2. anti-HBs negative and Anti-HBc positive
  3. anti-HC IgG (if positive IgG, HCV-RNA PCR will be performed and if negative, participant can be enrolled) 16. Use of other investigational drugs at the time of enrollment (Screening) or within the prior 30 days, or five elimination half-lives, or until the expected pharmacodynamic effect has returned to baseline, whichever is longer 17. Absolute neutrophil count (ANC) <750/mm3; 18. Hemoglobin <10.0 g/dL 19. Platelet count <100,000/mm3 20. Prothrombin time (PT) or international normalized ration (INR) >1.5 x ULN