Receptor-mediated clearance of Aspergillus galactomannan

Abstract

The fate of radiolabeled Aspergillusfumigatus galactomannan was studied after intrave-nous injection into rabbits and rats. At 1 hr, the liver contained 35 % of the injected dose in rabbits and 30070 in rats. Excretion of galactomannan into the urine, measured in rab-bits, was another major catabolic route and accounted for 35070 of the dose by 24 hr. Immunization of rabbits increased hepatic uptake and decreased urinary excretion. He-patic uptake in unimmunized rats could be decreased by Saccharomyces cerevisiae man-nan, a-methylmannoside, and N-acetylglucosamine, known inhibitors of the macrophage mannose receptor. Autoradiography showed hepatic radiolabeled galactomannan to be concentrated in Kupffer cells,whichexpress the mannosyl receptor for glycoproteins. Mac-rophage mannosyl receptors may constitute a general mechanism for clearing fungal man-nans from the bloodstream. Studies from this laboratory have found that both patients with aspergillosis and experimental animals infected with Aspergillus jumigatus have fungal galactomannan in their urine and blood [1]. Becaus