Naive B cells strongly depend on a functional LFA-1-ICAM interaction for T-cell activation. For analysis of T-cell proliferation in the presence of LFA-1-ICAM inhibitors, DO11.10 T cells were stained with CFSE before embedding with OVA-loaded APCs within 3-D collagen in the presence of antibodies against LFA-1-ICAM (A) or BIRT377 (B). Seventy-two hours after beginning of the coculture, gels were digested by collagenase, stained with anti-CD4, and analyzed by flow cytometry for cell division in the CD4 compartment. The rates of T-cell proliferation relative to the controls (anti-CD102 for antibodies, no inhibition for BIRT377) are shown. Data are representative of 3 independent experiments.