Figure 1.

Expression of B7.2 but not ICAM-1 promotes strong CD4⁺ T cell proliferative responses and cytokine production. D011 CD4⁺ cells purified as described in Materials and Methods were cultured with ova peptide and class II H2-A^d-positive Dros APC with the indicated costimulatory molecules. [³H]thymidine uptake of triplicate cultures was measured on days 2–5. Supernatant was removed before addition of [³H]thymidine for analysis of cytokine production by ELISA. (A) Kinetics of the proliferative response to 1 μM ova peptide. (B) Dose–response curve of D011 CD4⁺ cells stimulated with the indicated concentrations of ova peptide presented by Dros APC expressing the indicated murine accessory molecules. The response shown is that measured on day 5, the peak response in this particular experiment. (C and D) IL-2 and IL-4 accumulation in the above cultures was assessed on days 1–4; the peak IL-2 and IL-4 levels in the culture supernatant were observed with 10 μM ova, which is illustrated.