Tolerance Induction by CD40 Blocking through Specific Antibody in Dendritic Cells

Blocking antibodies are valuable tools for inhibiting the specific receptor- ligand interactions. The interaction of co-stimulatory molecules on the antigen presenting cells with their ligands on T cells is an essential step for T cell activation. In the present study, the effect of blocking antibody against CD40 on its T cell stimulatory potential is investigated.The DCs (dendritic cells) were collected from the mice spleens and then cultured in vitro. We used purified rat anti-mice CD40 (Clone HM40-3) (BD USA) as a blocking antibody and the appropriate titer of the blocking antibody was determined by flow cytometry. The DCs were then treated by antibody and used in MLR assay. The results of these experiments showed that CD40 blockade were associated with the increase in the of IL-4 secretion, shifting the DCs to stimulate Th2 cytokine production by the allogenic T cells, while the secretion of IL-12 by DCs decreased. Similarly, the DCs with reduced CD40 expression poorly responded to alloantigen stimulation in the MLR. Collectively, these results emphasize the importance of CD40 pathway in tolerogenic DCs generation and also support the idea that downregulation of CD40 is effective in inhibiting the allostimulatory function.