Figure 4.

Stimulation of human T cells by superagonistic anti-CD28 mAb in the presence and absence of TCR triggering. Freshly isolated human T cells from PBMC were cultured at 5 × 10⁵/ml in plates containing (A) or lacking (B) immobilized anti-CD3 mAb (suboptimal concentration of 0.003 μg/ml) and soluble anti-CD28 mAb7.3B6 (a representative costimulatory mAb), 9D7 or 5.11A1 (3 μg/ml; two novel superagonistic mAb). (C) Titration of anti-CD28 mAb in the absence of anti-CD3 mAb. (A–C) Cells were cultured for 3 d before the addition of [³H]thymidine. Data are representative for four (A and B) or two (C) independent experiments.