Co-expression of the CD45RA and CD45RO antigens on T lymphocytes in chronic arthritis

Clin Exp Immunol. 1994 Jul;97(1):39-44. doi: 10.1111/j.1365-2249.1994.tb06576.x.


The site of T lymphocyte activation in chronic arthritis is unknown. Peripheral blood (PB) lymphocytes from chronic arthritis patients are in a 'naive' or non-activated state, as defined by expression of the CD45RA antigen and lack of HLA class II expression. In contrast, most synovial fluid (SF) T lymphocytes express a 'memory' or activated phenotype, as defined by the CD45RO antigen and high HLA class II expression. Following stimulation, naive cells lose CD45RA and gain CD45RO expression to become memory cells with a transitional stage of dual CD45RA, CD45RO antigen expression. To localize where this change in phenotype occurs we used dual colour immunofluorescence labelling to compare the percentage of dual CD45RA, CD45RO-positive T lymphocytes in PB and SF from chronic arthritic patients and from normal PB, assuming this population would be increased at the primary site of T lymphocyte activation. Expression of the intermediate and late activation marker, HLA-DR, was also analysed using dual colour immunofluorescence labelling. The percentage of dual positive T lymphocytes was similar between arthritic PB, SF, and normal PB, as was the density of both CD45RA and CD45RO antigens. Thus, CD45 isoform expression did not indicate where T lymphocytes were activated. However, we identified a previously unreported population of CD45RA+ CD45RO+ HLA-DR- T lymphocytes in arthritic and normal PB. In SF, this population was absent, but a substantial number of dual CD45RA, CD45RO-positive HLA-DR+ T lymphocytes were identified. This population would not be predicted by the current model of T lymphocyte activation. Division of T lymphocytes into functional groups on the basis of CD45 isoform expression is likely to be more complicated than previously thought. Based on our findings we propose an alternative model of T lymphocyte differentiation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arthritis / blood
  • Arthritis / immunology*
  • Arthritis / pathology
  • Cell Differentiation
  • Chronic Disease
  • Fluorescent Antibody Technique
  • HLA-DR Antigens / metabolism
  • Humans
  • Immunologic Memory
  • Leukocyte Common Antigens / metabolism*
  • Lymphocyte Activation
  • Models, Biological
  • Phenotype
  • Synovial Fluid / cytology
  • Synovial Fluid / immunology
  • T-Lymphocytes / immunology*
  • T-Lymphocytes / pathology


  • HLA-DR Antigens
  • Leukocyte Common Antigens