Depletion of functionally active CD20+ T cells by rituximab treatment

Arthritis Rheum. 2009 Dec;60(12):3563-71. doi: 10.1002/art.24998.


Objective: Rituximab is a therapeutic anti-CD20 antibody used for in vivo depletion of B cells in proliferative and autoimmune diseases. However, the mechanisms of action are not fully understood, since not all of the therapy-mediated effects can be explained by the depletion of antibody-secreting cells. In addition to B cells, there is also a small population of T cells coexpressing CD20 in all individuals. This study was conducted to examine the phenotype and function of CD3+CD20+ T cells in patients with rheumatoid arthritis (RA) and healthy controls.

Methods: The phenotype and apoptosis of peripheral blood mononuclear cells from healthy donors and RA patients were examined by 4-color fluorescence-activated cell sorting analyses. Cytokine production was determined by intracellular staining and measurement of cytokines in the supernatants. Proliferation of sorted T cell populations was analyzed using 3H-thymidine uptake assays.

Results: In healthy individuals, 0.1-6.8% of peripheral blood T cells (mean 1.6%; n=142) coexpressed CD20, which was not significantly different from that in the peripheral blood of RA patients, in whom 0.4-2.6% of T cells (mean 1.2%; n=27) were CD20+. During rituximab therapy, the CD20+ T cells along with the B cells were eliminated from the RA peripheral blood. Among the CD20+ T cells, 45% coexpressed CD8 and 55% coexpressed CD4. Polyclonal CD3+CD20+ cells were functionally characterized by constitutive cytokine production (i.e., interleukin-1beta and tumor necrosis factor alpha), a low proliferative capacity, a high activation state, and enhanced susceptibility to apoptosis.

Conclusion: These findings suggest that CD20+ T cells represent a terminally differentiated cell type with immune-regulatory and proinflammatory capacities. Depletion of CD20+ T cells may be an additional mechanism by which anti-CD20 therapy functions in patients with RA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Monoclonal / pharmacology*
  • Antibodies, Monoclonal, Murine-Derived
  • Antigens, CD20 / metabolism
  • Apoptosis / drug effects
  • Biomarkers / metabolism
  • CD3 Complex / metabolism
  • Cell Proliferation / drug effects
  • Cytokines / metabolism
  • Flow Cytometry / methods
  • Humans
  • Immunologic Factors / pharmacology*
  • Leukocytes, Mononuclear / drug effects
  • Leukocytes, Mononuclear / immunology
  • Leukocytes, Mononuclear / pathology
  • Phenotype
  • Rituximab
  • T-Lymphocyte Subsets / drug effects
  • T-Lymphocyte Subsets / immunology
  • T-Lymphocyte Subsets / metabolism
  • T-Lymphocytes / drug effects*
  • T-Lymphocytes / immunology
  • T-Lymphocytes / pathology


  • Antibodies, Monoclonal
  • Antibodies, Monoclonal, Murine-Derived
  • Antigens, CD20
  • Biomarkers
  • CD3 Complex
  • Cytokines
  • Immunologic Factors
  • Rituximab