Cytokines were measured by enzyme-linked immunosorbent assays (ELISAs; Biolegend); T-cell survival in vitro was determined by trypan blue (Sigma-Aldrich) exclusion assay; and proliferation was measured in triplicate cultures by incorporation of [3H]thymidine (1 µCi/well; ICN Pharmaceuticals, Laval, qC, Canada) during the last 12 h of culture (73 (link)).