Treatment with annexin V increases immunogenicity of apoptotic human T-cells in Balb/c mice

Exposure of phosphatidylserine on the outer leaflet of the cytoplasmic memb rane is an early event during apoptotic cell death and serves as a recognit ion signal for phagocytes. Usually the clearance of apoptotic cells does no t initiate inflammation or immune response. We investigated the immune resp onse in Balb/c mice towards apoptotic human T-cells, Animals injected with apoptotic cells showed significantly reduced humoral immune responses, espe cially Th1-dependent IgG2a titres, compared to controls immunised with viab le cells, However, treatment of apoptotic cells with annexin V (AxV) signif icantly increased the humoral immune response, AxV binds with high affinity to anionic phospholipids and as a result interferes with the phosphatidyls erine recognition by phagocytes, Our results indicate that AxV treatment ma y be used to increase the efficiency of apoptotic cell-based vaccines, e.g. some tumour vaccines.