Features of Human CD3+CD20+ T Cells

Area of Science:

• Immunology
• Neuroimmunology

Background:

• Monoclonal antibodies targeting CD20 are used to treat multiple sclerosis (MS), primarily by depleting B cells.
• A controversial subset of T cells co-expressing CD3 and CD20 (CD3(+)CD20(+)) has been recently described and is also targeted by anti-CD20 therapy.

Purpose of the Study:

• To confirm the existence and characterize the phenotype and function of CD3(+)CD20(+) T cells.
• To investigate the distribution and behavior of these cells in the context of multiple sclerosis and its treatments.

Main Methods:

• Flow cytometry and gene transcription analysis to identify and quantify CD3(+)CD20(+) T cells.
• Analysis of cell distribution in various tissues and cerebrospinal fluid.
• Phenotypic characterization using markers like CD8, CD45RO, and CCR7.
• Assessment of cytokine production (IL-4, IL-17, IFN-γ, TNF-α).
• Evaluation of T cell responses to MS disease-modifying drugs.

Main Results:

• Confirmed that 3-5% of circulating human T cells are CD3(+)CD20(+).
• These cells are present in thymus, bone marrow, lymphatic organs, and cerebrospinal fluid, even without inflammation.
• CD3(+)CD20(+) T cells are enriched in CD8(+) memory cells and show higher cytokine production compared to CD20(-) T cells.
• Observed variable responses to MS treatments: reduced by fingolimod, alemtuzumab, dimethyl fumarate; increased by natalizumab.
• CD3(+)CD20(+) T cells repopulated faster and at higher levels than B cells after rituximab treatment.

Conclusions:

• Human CD3(+)CD20(+) T cells are a distinct subpopulation with a significant presence in immune organs and the central nervous system.
• These cells possess potent cytokine-producing capabilities and play a role in the immunopathogenesis of MS.
• Their differential response to MS therapies highlights their importance in treatment strategies and suggests potential therapeutic targeting.