Augmented TNF-alpha and IL-10 production by primed human monocytes following interaction with oxidatively modified autologous erythrocytes

The presence of dysfunctional/damaged red blood cells (RBCs) has been assoc iated with adverse clinical effects during the inflammatory response. The a im of this study was to elucidate whether oxidatively modified, autologous, RBCs modulate monocyte cytokine responses in humans. Monocyte tumor necros is factor alpha (TNF-alpha) and IL-10 production was measured in whole bloo d from healthy volunteers using ELISA and flow cytometry. Oxidatively modif ied RBCs (15 m.M phenylhydrazine, 1 h, OX-RBQ or vehicle-treated RBCs (VT-R BC) opsonized by autologous serum were administered alone or in combination with one of three priming agents: E. coli lipopolysaccharide (LPS, 0.2 ng/ ml), zymosan A (1 mg/ml), or phorbol 12-myristate 13-acetate (PMA, 50 ng/ml ). OX-RBC or W-RBC alone did not result in the release of TNF-alpha or IL-1 0. LPS, zymosan, and PMA caused marked and dose-dependent increases in TNF- alpha and IL-10 production. Addition of OX-RBC augmented the LPS-, zymosan- , and PMA-induced TNF-alpha release by approximately 100%. OX-RBC augmented LPS- and zymosan-mduced IL-10 release by 400-600%. Flow cytometry analyses showed that monocytes were responsible for TNF-alpha and IL-10 production in whole blood. The presence of OX-RBC alone increased the complexity of CD 14+ monocytes but caused no cytokine production. LPS alone induced cytokine production without altering cell complexity. After the combined (OX-RBC+LP S) treatment, monocytes of high complexity were responsible for TNF-alpha p roduction. The presence of mannose or galactose (at 10-50 mM) did not alter the observed augmentation of cytokine production by OX-RBC, suggesting tha t lectin receptors are not involved in the response. These studies indicate that the interaction between damaged autologous erythrocytes and monocytes has a major impact on the cytokine responses in human. An augmented cytoki ne production by the mononuclear phagocyte system may adversely affect the clinical course of injury and infections especially in genetic or acquired RBC diseases or after transfusions.