Peripheral blood‐derived bovine dendritic cells promote IgG1‐restricted B cell responses in vitro

Regulation of humoral responses in- volves multiple cell types including the require- ments for cognate interactions between T and B cells to drive CD40-dependent responses to T-de- pendent antigens. A third cell type has also been shown to play an essential role, the dendritic cell (DC). We demonstrate that bovine peripheral blood-derived (PB)-DC are similar in function to features described for human interstitial DC in- cluding the production of signature type 2 cyto- kines (interleukin (IL)-13, IL-10). PB-DC express moderate-to-high costimulatory molecule expres- sion, and major histocompatibility complex class II is negative for CD14 expression and has low or no expression of CD11c. Consistent with the intersti- tial phenotype is the ability of PB-DC to influence B cell activation and differentiation via direct ex- pression of CD40L and type 2 cytokines. Collec- tively, these results suggest that direct B cell-DC interactions may promote an immunoglobulin-iso- type expression pattern consistent with type 2 re- sponses, independent of direct T cell involvement. J. Leukoc. Biol. 73: 100-106; 2003.