Mechanisms of the adjuvant effect of hemoglobin in experimental peritonitis. IV. The adjuvant effect of hemoglobin in granulocytopenic rats

Intraperitoneal inocula of pure Escherichia coli do not produce lethal peritonitis unless adjuvant materials are present. We have previously presented evidence that hemoglobin acts as an adjuvant in experimental Escherichia coli peritonitis by interfering with antibacterial neutrophil function. The hypothesis was further tested in normal Sprague-Dawley rats and rats depleted of granulocytes by pretreatment with busulfan and cyclophosphamide. Hemoglobin increased the lethality of Escherichia coli peritonitis in both neutropenic and normal rats. Furthermore, the early clearance of bacteria from the peritoneal cavity was equally depressed by hemoglobin in neutropenic and normal rats. We conclude that hemoglobin has some effect on intraperitoneal infections beyond its suppression of granulocyte function. This additional effect may represent interference with bacterial lymphatic absorption or peritoneal or systemic macrophage function or may be a manifestation of a nutritional effect of hemoglobin on bacterial growth.