Tolerance Induction by CD40 Blocking through Specific Antibody in Dendritic Cells

Blocking antibodies are valuable tools for inhibiting the specific receptor- ligandinteractions. 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 andthe 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 theincrease in the of IL-4 secretion, shifting the DCs to stimulate Th2 cytokine production bythe allogenic T cells, while the secretion of IL-12 by DCs decreased. Similarly, the DCs withreduced CD40 expression poorly responded to alloantigen stimulation in the MLR.Collectively, these results emphasize the importance of CD40 pathway in tolerogenicDCs generation and also support the idea that downregulation of CD40 is effective ininhibiting the allostimulatory function.