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 membrane is an early event during apoptotic cell death and serves as a recognition signal for phagocytes. Usually the clearance of apoptotic cells does not initiate inflammation or immune response. We investigated the immune response in Balb/c mice towards apoptotic human T-cells, Animals injected with apoptotic cells showed significantly reduced humoral immune responses, especially Th1-dependent IgG2a titres, compared to controls immunised with viable cells, However, treatment of apoptotic cells with annexin V (AxV) significantly increased the humoral immune response, AxV binds with high affinity to anionic phospholipids and as a result interferes with the phosphatidylserine recognition by phagocytes, Our results indicate that AxV treatment may be used to increase the efficiency of apoptotic cell-based vaccines, e.g. some tumour vaccines.