Expression of activation antigens on T cells in rheumatoid arthritis patients.

The aim of our study was to identify differences in cell surface marker expression between T cells taken from the peripheral blood (PB) of healthy individuals and T cells recovered from inflamed joints of rheumatoid arthritis (RA) patients. Out of 118 monoclonal antibodies (MoAbs) directed against activation antigens on haematopoietic cells, 12 MoAbs recognizing nine distinct surface molecules were selected after a screening procedure to study the expression of the corresponding antigens on T cells from the PB, synovial fluid and synovial tissue of RA patients, and also on T cells from PB and spleens of controls. Using two-colour flow cytometry and immunohistology we found the molecules B-C5, CD39, CD40, CD45 R0, CD54, CD76 and potentially 1D11 to be substantially up-regulated on T cells from various body compartments in RA patients. We thus could determine that the cell surface of T cells in RA patients not only differs in MHC class II expression, but also in a number of other activation-associated cell surface molecules from T cells in healthy individuals.