Figure 1.

CD2–CD48 and LFA-1–ICAM-1 interactions enhance T cell proliferation at low peptide densities. Thioglycollate-elicited macrophages derived from control (filled symbols) or ICAM-1–deficient (open symbols) mice were pulsed with various doses of peptide p33 or the low-affinity ligand A4Y and used to stimulate T cells derived from TCR-transgenic control (squares) or CD2-deficient (circles) mice. Proliferation was assessed 36 h later by means of [³H]thymidine incorporation. Two independent experiments are shown. ▪, CD2⁺ICAM⁺; •, CD2⁻ICAM⁺; □, CD2⁺ICAM⁻; ○, CD2⁻ICAM⁻.