hFcγRIa triggered antigen presentation depends on newly synthesized proteins and on protein serine kinase activity. (A) Transfectants were incubated in RPMI 1640 medium alone or medium with cycloheximide (CH) and either 100 ng/mL rabbit IgG-OVA complexes or OVA alone. B) Transfectants were incubated in medium alone or medium with H7 and either 100 ng/mL rabbit IgG-ovalbumin complexes or ovalbumin alone. For both (A and B), cells were then washed and incubated with OVA-specific T cells for 16 hours. Levels of IL-2 released by T cells were determined by CTLL proliferation assays. Data represent means of duplicate determinations in a single experiment, repeated at least four times, with essentially identical results.