Crotoxin Isolated from Venom Modulates the Functional Activity of Dendritic Cells via Formyl Peptide Receptors.

The rattlesnake venom, its main toxin, crotoxin (CTX), and its crotapotin (CA) and phospholipase A (CB) subunits modulate the immune system. Formyl peptide receptors (FPRs) and lipoxin A (LXA) are involved in CTX's effect on macrophages and neutrophils. Dendritic cells (DCs) are plasticity cells involved in the induction of adaptive immunity and tolerance maintenance. Therefore, we evaluated the effect of CTX, CA or CB on the maturation of DCs derived from murine bone marrow (BM). According to data, CTX and CB-but not CA-induced an increase of MHC-II, but not costimulatory molecules on DCs. Furthermore, CTX and CB inhibited the expression of costimulatory and MHC-II molecules, secretion of proinflammatory cytokines and NF-Bp65 and p38/ERK1/2-MAPK signaling pathways by LPS-incubated DCs. Differently, CTX and CB induced IL-10, PGE and LXA secretion in LPS-incubated DCs. Lower proliferation and IL-2 secretion were verified in coculture of CD3 cells and DCs incubated with LPS plus CTX or CB compared with LPS-incubated DCs. The effect of CTX and CB on DCs was abolished in cultures incubated with a FPRs antagonist. Hence, CTX and CB exert a modulation on functional activity of DCs; we also checked the involvement the FPR family on cell activities.