(A) Naive B cells pre-activated with anti-IgM were cultured in the presence of CpG and SEB with autologous CD4+ T cells primed with the indicated cytokines. Ig titers in the supernatants were measured at day 14. Mean ± s.e.m. n=6. Unpaired two-tailed t-test. A representative out of three experiments.
(B) Memory B cells were cultured in the presence of SEB with autologous CD4+ T cells primed with the indicated cytokines. Ig levels at day 14. Mean ± s.e.m. n=6. Unpaired two-tailed t-test. A representative out of three experiments.
(C) Ig secretion from memory B cells cultured with CD4+ T cells primed with titrated amounts of IL-12. A representative out of two experiments.
(D) IL-21R-Fc was added to block IL-21 to the co-cultures of memory B cells and CD4+ T cells primed with IL-12. Ig levels at day 14. Mean ± s.e.m. n=6. Unpaired two-tailed t-test. A representative out of three experiments.
(E) Blocking of ICOS by ICOS-L-mIgFc during T-B cultures. Ig levels at day 14. Mean ± s.e.m. n=6. Unpaired two-tailed t-test. A representative out of three experiments.