CD4~+ CD25~+ regulatory T cells exhibit cytotoxicity against dendritic cells
Objective To investigate whether CD4~+ CD25~+ regulatory T cells could regulate dendritic cells.Methods CD4~+ CD25~+ regulatory T cells were isolated by MACS(magnetic cell sorting)from naive BALB/ c mice.Their suppression on the proliferation of CD4~+ CD25~- T cells was analyzed by cell proliferation assay.Au- tologous DCs were prepared from bone marrow progenitors and cultured with GM-CSF/IL-4.The characters of these DCs were analyzed by FACS.CD4~+ CD25~+ regulatory T cells were activated by CD3/CD28 antibodies and their cytotoxic effects on autologous DCs were evaluated in vitro by flow-based killing assay.To analyze the role of the pefforin/granzyme pathway in killing,EGTA was added to inhibit calcium-dependent pefforin polymerization.Re- sults It was found that DCs derived from bone marrow expressed CD11c,MHCⅡand low levels of other co-stim- ulatory molecules such as CDS0,CD86.CD4~+ CD25~+ regulatory T cells could be successfully classified by MACS with 98% purity and specifically express the Foxp3 gene.CD4~+ CIY25~+ regulatory T cells stimulated by CD3/ CD28 exhibited cytotoxic effects on autologous DC targets(P＜0.05),and the process could be partially inhibited by EGTA(P＜0.05).Conclusion CD4~+ CD25~+ regulatory T cells could regulate immune response by killing autologous DCs,and perforin/granzyme pathway might participate in this process.