Effect of Bacterial Endotoxin on Experimental Fungal Infections

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Abstract
Summary: Escherichia coli endotoxin was administered to mice prior to challenge with 5 × 106 Candida albicans, 5 × 106 Rhizopus arrhizus or 1 × 106 Blastomyces dermatitidis organisms. When 100 or 400 µg endotoxin was given 1 hr prior to challenge with C. albicans, significant acceleration in mortality occurred, while the same doses of endotoxin given 24 hr before challenge delayed lethality. Similar protection but no enhancement of lethality was noted for R. arrhizus, while reproducible alterations in lethality were not demonstrable with B. dermatitidis. Protection against C. albicans appeared to have a bimodal character, being maximal at 24 hr and 6 days following endotoxin administration. Sterile sera were passively administered in amounts of 1.0 ml to normal mice, which were then challenged 1 hr later with C. albicans. Lethality was significantly delayed only in the animals receiving sera collected 24 hr after endotoxin but not in the groups receiving saline, normal sera or sera obtained 6 days following endotoxin. These studies demonstrate that serum factors are important in the initial phase of increased resistance against C. albicans induced by endotoxin.