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Keywords:

  • DC;
  • HLA-G;
  • Immunomodulation;
  • NK cells;
  • NK/DC crosstalk

Abstract

HLA-G molecules are known to exert immunosuppressive action on DC maturation and on NK cells, and can in consequence inhibit respectively T cell responses and NK cytolysis. In this study, we show that monocyte-derived DC, differentiated in the presence of GM-CSF and IL-4, are sensitive to soluble (s) HLA-G molecules during LPS/IFN-γ maturation as demonstrated by the decrease of CD80 and HLA-DR expressions and IL-12 secretion. Moreover, DC pretreated with sHLA-G were found to activate NK/DC crosstalk less than non-treated DC. Early activation of NK cells co-cultured with autologous DC was diminished as assessed by CD69 expression. The IFN-γ production was impaired whereas a slight inhibition of the NK cell cytotoxicity against Daudi cell line was observed. Since sHLA-G is expressed in grafts or sites of tumour proliferation, its indirect action on NK cells via DC could constitute a pathway of early inhibition for both innate and specific immune responses.