Regulatory activity of antigen-specific T-cell responses by autoantigen-specific Tr clones derived from a patient with AIHA. Tr clone P8(1) inhibits proliferation by unfractionated autologous CD4+ T cells responding to APCs presenting the Rh protein autoantigen. The ratio of clones to autologous CD4+ T cells was 1:50 (10 000) and 1:12.5 (40 000), respectively. Proliferation was measured after 96 hours at 37°C, 5% CO2. All data shown are representative of 4 separate experiments with clone P8(1), and similar results were obtained with the other lines obtained from the patient. Data are presented as mean plus or minus standard error.