Presentation of IgA-OVA by FcαR/γ-chain transfectants is diminished in cells with altered γ chain.

(A) IIA1.6 B cells were cotransfected with FcαR and either WT γ chain (indicated with black bars), γ chain with IIA ITAM (indicated with cross-hatched bars), or γ chain with Y→ F mutation (indicated with gray bars). Transfectants and DO-11-10 OVA-specific T cells were incubated with various concentrations of NIP-haptenated OVA (NIP-OVA) opsonized with an IgA anti-NIP antibody. IL-2 secretion by the T cells was quantified as a measure of antigen presentation, as described in “Materials and methods.” (B) Nontargeted OVA is presented equally by WT or altered γ-chain transfectants. FcαR transfectants with WT γ chain (indicated with black bars), IIA ITAM γ chain (indicated with cross-hatched bars), or Y→ F γ chain (indicated with gray bars) were incubated together with DO-11-10 T cells and OVA at the concentrations indicated, and IL-2 secretion was measured as given in panel A. Similar results were obtained in 3 separate experiments.