Endotoxemia is masked in fungal infection due to enhanced endotoxin clearance by beta-glucan.

Employing a novel turbidimetric assay, the amount of endotoxin and beta-glucan in plasma was monitored in postoperative patients suffering from both bacterial and fungal infections. The patients, whose beta-glucan level was markedly elevated, were always negative for endotoxin, suggesting a possible role of beta-glucan in the clearance of circulating endotoxin. In order to test the above hypothesis, effects of beta-glucan (carboxy methylated curdlan or lentinan) on endotoxin clearance were studied in rabbits. beta-glucan (4 micrograms/kg or 40 micrograms/kg) was intravenously administered to rabbits which received 4 micrograms/kg endotoxin injection, simultaneously or 120 min before the injection. Either of the beta-glucans increased the endotoxin clearance in a dose-dependent manner, and the preinjection of beta-glucan was more effective than the coinjection. The increased amount of plasma beta-glucan results in the unexpectedly low level of plasma endotoxin, which may be removed by the reticuloendothelial system activated by beta-glucan, in cases with both bacterial and fungal infections. Thus, it is important to recognize that endotoxemia may be masked by the coexisting fungal infection.