Hemoglobin and Escherichia coli , a Lethal Intraperitoneal Combination

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Abstract
Intraperitoneal injection into mice of approximately 8 × 10 6 washed cells of Escherichia coli suspended in a lysate of washed human red blood cells or an aqueous solution of crystalline hemoglobin was lethal. E. coli suspended in washed intact erythrocytes, whole blood, plasma, or saline was innocuous. Fractionation of non-hemoglobin proteins from hemoglobin in lysates showed that only hemoglobin promoted a lethal infection. Overwhelming intraperitoneal growth of E. coli was attained in about 12 hr in lethal infections. The polymorphonuclear leukocytic response was ineffective against this rapid growth. The lethal mechanism is hypothesized to center on a unique role for free hemoglobin in inhibiting peritoneal absorption and stimulating an intraperitoneal exudate which supports luxuriant bacterial growth. Death is attributed to a lethal intoxication from bacterial endotoxins. This role for hemoglobin involves neither enhanced bacterial virulence nor lowered host resistance, and it would be of importance not only in peritonitis but also in problems where hemolysis and infection coexist.