LCL express high levels of the costimulatory molecules CD80 and CD86 but fail to activate iNKT cells. (A) Untreated naive B cells (○) and naive B cells treated with blocking αCD1d (●) and LCL (▪) were loaded with αGalCer and cultured with human iNKT cell lines (BM2a.3, J3N.5, and M0) for 48 hours. IFN-γ secretion by iNKT cells was measured by ELISA performed in triplicate (n = 10). ***P < .001. (B) Representative CD80, CD86, and isotype control staining of naive B cells and EBV-transformed B cells (LCL). MFI values indicate the level of CD80 and CD86 expression above the isotype control on naive B cells (○) and LCL (▪) generated from unrelated tonsil samples (n = 10). ***P < .001.