In vitro immunosuppressive activity of soluble HLA class I and Fas ligand molecules: do they play a role in autologous blood transfusion?

BACKGROUND: The immunomodulatory effects of allogeneic blood transfusion ma y contribute to a poor prognosis in patients with cancer who are undergoing surgery, and clinical trials have been carried out to investigate whether these patients would benefit from autologous blood donation. As the immunom odulatory effects of allogeneic blood transfusion have been related to solu ble molecules released from residual WBCs during storage, the in vitro immu nomodulatory activity of soluble molecules detected in supernatants from st ored autologous blood was evaluated. STUDY DESIGN AND METHODS: Blood was donated by four healthy volunteers. Pac ked WBC-reduced RBCs were obtained and stored for 30 days, and supernatants were collected. FFP and serum were also obtained. The concentration of sol uble molecules was determined by immunoenzymatic assays. The in vitro immun omodulatory activity of undiluted blood component supernatant was assessed by antigen-specific cytotoxic T-cell activity and mixed lymphocyte reaction s in autologous combinations and by apoptosis induction in Fas+ cells. RESULTS: The concentrations of soluble Fas-ligand and HLA class I molecules were higher in packed RBCs than in WBC-reduced RBCs, FFP, and serum. Undil uted supernatants of packed RBCs strongly inhibited functional assays and i nduced apoptosis in Fas+ cells. The immunomodulatory effects were correlate d with the amount of soluble Fas ligand and HLA class I molecules. CONCLUSION: The results of the present study are comparable with those alre ady reported in allogeneic blood components, and they indicate that undilut ed supernatants of autologous blood components may exert immunosuppressive effects in vitro.