Oxygen-independent killing of Bacteroides fragilis by granule extracts from human polymorphonuclear leukocytes.

AUTOR(ES)

Wetherall, B L

RESUMO

Granule proteins from human neutrophils were prepared by extraction with acetate, and their antibacterial activity against Bacteroides fragilis was determined. Activity was highly dependent on pH; greatest killing occurred at the most acid pH tested (pH 5.0). Optimum activity was observed at physiological ionic strength and low bacterial numbers. Killing was inhibited by incubation temperatures of less than 37 degrees C. Eight times more extract was required to kill 50% of stationary-phase bacteria, compared with those growing in logarithmic phase. The antibacterial effect of granule extract was destroyed by boiling, but some activity was retained after heating to 56 degrees C and 80 degrees C. Granule extract activity was tested under conditions in which oxygen-dependent antibacterial systems were inhibited. The rate and extent of killing was not affected by anaerobiosis, sodium azide, or cysteine hydrochloride. These results suggest that the activity of granule extract is independent of oxidative antibacterial systems, and therefore, under conditions that occur in anaerobic infections, potent leukocyte granule-associated mechanisms exist for the destruction of B. fragilis.

Documentos Relacionados

• Oxygen-independent intracellular and oxygen-dependent extracellular killing of Escherichia coli S15 by human polymorphonuclear leukocytes.
• Gonococci with mutations to low-level penicillin resistance exhibit increased sensitivity to the oxygen-independent bactericidal activity of human polymorphonuclear leukocyte granule extracts.
• Participation of normal human immunoglobulins M, G, and A in opsonophagocytosis and intracellular killing of Bacteroides fragilis and Bacteroides thetaiotaomicron by human polymorphonuclear leukocytes.
• Specificity of immunoglobulin M antibodies in normal human serum that participate in opsonophagocytosis and intracellular killing of Bacteroides fragilis and Bacteroides thetaiotaomicron by by human polymorphonuclear leukocytes.
• Bactericidal activity of fractionated granule contents from human polymorphonuclear leukocytes.