CD20(+) T cells have a predominantly Tc1 effector memory phenotype and are expanded in the ascites of patients with ovarian cancer

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 IFN gamma (similar to 70% vs. similar to 20% in the CD20(+) T cell population) and were predominantly (CD8(+)) effector memory T cells (similar to 60-70%). This IFN gamma 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 similar to 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 IFN gamma producing phenotype and are present in increased amounts in ascitic fluid of OC patients.