T cell subsets in the blast cell population in phytohemagglutinin-stimulated peripheral blood in vitro and in rheumatoid arthritis synovial fluid in vivo.

The immunomodulatory T4/T8 ratio was studied in the total and activated lymphocyte populations by a method combining visualisation of 3H-thymidine incorporating blasts with autoradiography (AR) with simultaneous identification of the respective lymphocyte subsets using monoclonal antibodies in avidin-biotin-peroxidase complex (ABC) staining. In rheumatoid arthritis synovial fluid the activated T4/T8 ratio (calculated from T cells in the S phase of the cell cycle) was significantly different from the total T4/T8 ratio (calculated for all the T cells) (0.45 +/- 0.05 versus 0.69 +/- 0.05, P less than 0.01). Similarly, the activated and total T4/T8 ratios were also significantly different in the phytohemagglutinin (PHA)-stimulated peripheral blood mononuclear cell cultures at days 3 and 5.