Effect of IL-7 on Ig production by PBMCs from healthy subject. (A) IL-7 increases IgE production by IL-4–stimulated PBMCs. IL-4–stimulated PBMCs were incubated with 10 ng/mL of the different cytokines and IgE was quantified by ELISA. (B) IL-7 increases IgE and IgG4 production in a dose-dependent manner. PBMCs were stimulated with IL-4 with or without 0.5 to 50 ng/mL of IL-7. IgE (□) and IgG4 (1:10) (▪) were quantified by ELISA. (C) Effect of IL-7 on the production of other isotypes by 200 U/mL of IL-4–stimulated PBMCs. PBMCs were stimulated with 200 U/mL of IL-4 without (□) or with (▪) 10 ng/mL of IL-7 before quantification of IgA1, IgA2, IgG1-3, and IgM by ELISA. (D) IL-7 potentiates IL-4–induced IgE and IgG4 production in the absence of anti-CD40 MoAb. IgE and IgG4 were quantified in the supernatants of PBMCs either unstimulated or stimulated with IL-4, anti-CD40 MoAb, or combination of IL-4 plus anti-CD40 MoAb in the absence (□) or presence (▪) of 10 ng/mL IL-7. (A-D) Ig isotypes were quantified in the day-12 supernatants. Results are expressed in ng or μg/mL (as mean ± SD of quintuplicate values) and are representative of one of four (A and C) or six (B and D) separate experiments. * indicates P < .01.