Recently, a small subset of T cells that expresses the B cell marker CD20 has been identified in healthy volunteers and in patients with rheumatoid arthritis and multiple sclerosis. The origin of these CD20-positive T cells as well as their relevance in human disease remains unclear. Here, we identified that after functional B cell/T cell interaction CD20 molecules are transferred to the cell surface of T cells by trogocytosis together with the established trogocytosis marker HLA-DR. Further, the presence of CD20 on isolated CD20+ T cells remained stable for up to 48h of ex vivo culture. These CD20+ T cells almost exclusively produced IFNγ (∼70% vs. ∼20% in the CD20- T cell population) and were predominantly (CD8+) effector memory T cells (∼60-70%). This IFNγ producing and effector memory phenotype was also determined for CD20+ T cells as detected in the peripheral blood and ascitic fluids of ovarian cancer (OC) patients. In the latter, the percentage of CD20+ T cells was further strongly increased (from ∼6% in peripheral blood to 23% in ascitic fluid). Taken together, the data presented here indicate that CD20 is transferred to T cells upon intimate T cell/B cell interaction. Further, CD20+ T cells are of memory and IFNγ producing phenotype and are present in increased amounts in ascitic fluid of OC patients.
Keywords: APC, Antigen-Presenting Cell; Ascites; CD20; CTL, Cytotoxic T Lymphocyte; FSC, Forward Scatter; OC, Ovarian Cancer; PBMC, Peripheral Blood Mononuclear Cell; Regulatory T cell; SCC, Side Scatter; TC, Cytotoxic T cell; TCM, Central Memory T cell; TEM, Effector Memory T cell; TH, Helper T cell; TIL, Tumor Infiltrating T cell; TNaïve, Naïve T cell; TTD, Terminally Differentiated T cell; Treg; cancer immunology; ovarian cancer; trogocytosis.