Downregulation of Major Histocompatibility Complex Class I Expression in Polymorphonuclear Leukocytes by Triggering CD 1 6 Antigen

抄録

Polymorphonuclear leukocytes (PMNs) constitutively express major histocompatibility complex (MHC) class I molecules on their surface. In spite of the prominent roles of PMNs in host immune defense, the roles of MHC class I molecules in PMNs, such as presenting intracellularly processed antigens to CD8+ T cells, or preventing the cytotoxic effect of natural killer (NK) cells by their upregulated expression levels, have not been fully investigated thus far. PMNs express two low-affmity Fc T receptors, Fc 7 R 11 (CD32) and Fc T R III (CD16). The intracellular signaling pathway of PMNs is activated by triggering or cross-linking CD 16, resulted in the upregulation of MHC class I expression. We found that the expression levels of MHC class I molecules of PMNs could be downregulated by triggering CD 16, but not by triggering CD32.