Naive OVA-Tg CD4⁺ cells secrete IL-4 following primary antigen activation in vitro in the presence of spleen from TLI-preconditioned mice.

Purified naive OVA-Tg CD4⁺ cells were cultured for 48 hours with increasing concentrations of OVA peptide and APCs from either untreated (BALB/c, solid symbols) or TLI-preconditioned (TLI, open symbols) BALB/c mouse spleen without (circles) or with (squares) anti-CD28. IL-4 (A) and IFN-γ (B) secretion was quantitated by ELISA of culture supernatants. Symbols represent the means of duplicate determinations of IL-4 and IFN-γ for one experiment. The ELISA detection limits were 1 pg/mL (IL-4) and 5 pg/mL (IFN-γ). The figure depicts one representative experiment of 3 separate experiments.