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Increased in vitro Immunosuppressive Action of Anti‐CMV and Anti‐HBs Intravenous Immunoglobulins due to Higher Amounts of Interferon‐Gamma Specific Neutralizing Antibodies

Background and objectives: We previously found that interferon‐γ (IFN‐γ) antibodies in intravenous immunoglobulins (IVIG) can block not only IFN‐γ production and tumor necrosis factor‐α secretion, but also T‐cell proliferation. Since the presence of IFN‐γ antibodies has been attributed to previous viral infection, we hypothesized that the viral status of the plasma donors used for IVIG pools might be a decisive factor in controlling the immunosuppressive capacity of IVIG. Materials and methods: We tested three different pooled, human IVIG preparations for the presence of IFN‐γ antibodies by ELISA. Results: Comparison of the immunomodulatory activity of polyvalent IVIG with that of specific CMV and HBs IVIG showed that the latter had higher levels of IFN‐γ antibodies and an increased capacity to block mixed lymphocyte reaction and cytokine production. Conclusion: We propose that these in vitro assays constitute a basis for the selection of plasma intended for manufacturing IVIG aimed at immunosuppression in the transplant setting.