Expansion of non-classic CD4+CD28null T cells in patients with RA and CAD. Frequencies of CD4+CD28null T cells were determined by flow cytometry. Data are presented as box plots with medians, 25th and 75th percentiles as boxes and 10th and 90th percentile as whiskers. CD4+CD28null T cells are infrequent in donors with stable angina and are significantly expanded in patients with unstable angina (P = 0.009). Patients with RA and CAD resemble patients with plaque instability and differ from those with stable angina (P = 0.001).