Figure 2.

Skewed distribution of CD4⁺CD28^null T cells in synovial fluid and peripheral blood. (a) Paired samples of synovial fluid (SF) and peripheral blood (PB) from 128 rheumatoid arthritis patients were compared for the frequency of CD4⁺CD28^null T cells by flow cytometry. (b) Frequencies of CD4⁺CD28^null T cells in SF tend to be higher in patients with large populations in PB. (c) Comparison of the frequency of CD4⁺CD28^null T cells in SF from two different synovial compartments. Open circle, elbow; open squares, shoulder joints. Frequencies of CD4⁺CD28^null T cells in (d) SF and (e) PB in patients seronegative and seropositive for human cytomegalovirus (HCMV). (f) Frequencies of CD4⁺CD28^null T cells in paired PB and SF of patients seropositive for HCMV.