Induction of T-cell tolerance to platelet Ags for patients with chronic AITP.

T cells (1 × 10⁶/mL) from 36 patients were incubated with acid-treated platelets and APCs in the presence of CTLA4-Ig (10 μg/mL) and/or CsA (400 ng/mL). After 7 days of incubation the cells were washed and rested for 2 days (primary culture), and then rechallenged with acid-treated platelets in the presence of APCs but without CTLA4-Ig or CsA (secondary culture) (A) for different culture periods in the first 3 patients to determine the kinetics of T-cell proliferation during secondary stimulation, and (B) for 4 days in all 36 patients to define the effects of CTLA4-Ig and/or CsA on the induction of T-cell tolerance. Proliferation was measured by incorporation of [³H]thymidine and shown as mean ± SD cpm.