Active LFA-1 on DCs negatively influences T-cell proliferation. Mature DCs from wild-type (WT) and LFA-1^d/d mice were loaded with ovalbumin peptides and cocultivated in different concentrations with naive CD4⁺ OT-II (A) and CD8⁺ OT-I (B) in a 3-D collagen gel for 3 days. Cell proliferation was assessed by incorporation of [³H]thymidine. Assays were performed in triplicate. One representative assay of 3 is shown. cpm indicates counts per minute.