Biphasic CD40L expression is IL-4 independent. PBMCs were stimulated with OKT3 ± anti-CD28 mAb. Gating was performed on CD4⁺ lymphocytes. (A) Anti–IL-4 or isotype control mAb was added to parallel cultures. (B-C) Costimulated PBMCs were cultured ± rIL-4. The mean ± SE of 4 donors are shown. (D) Anti–IL-12 and anti–IL-12R mAb or isotype controls were added to parallel cultures. The mean ± SE of 3 donors are shown. (E) Stimulated PBMC cultures ± rIL-12. The means ± SE of 5 donors are shown. (F) Stimulated PBMC cultures ± rIL-12 ± anti-CD25 mAb. The mean ± SE of 5 donors are shown.