Effects of Liposome-Encapsulated Hemoglobin on Phorbol Ester-Induced Superoxide Production and Expression of Costimulatory Molecules by Monocytes in Vitro

Abstract

The effects of Neo Red Cell (NRC), a liposome-encapsulated hemoglobin (LEH), on the phorbol ester-induced superoxide production and the expression of costimulatory molecules by human peripheral monocytes were investigated. The treatment of human mononuclear cells with NRC caused the potentiation of superoxide production in response to PMA. The longer incubation (20 h) resulted in a decrease in the PMA-induced superoxide production, which was in parallel to a decrease in the viability of the monocytes. A flow cytometric analysis showed that a slight expression of CD80 (B7-1) on monocytes was induced by NRC treatment, whereas the constitutive expressions of CD86 (B7-2) and CD54 (ICAM-1) were unchanged. The activation of monocytes with interferon-γ (IFN-γ) induced the expressions of CD80, CD86, and CD54 under all conditions tested, but NRC treatment tended to decrease the IFN-γ-induced expression of CD54 on monocytes. These results suggest that the administration of LEH may modify the functions of human monocytes.