クリプトコッカスに対する好中球の貪食殺菌活性と莢膜多糖体による抑制

概要

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Cryptococcus neoformans is an opportunistic fungal pathogen, which frequently causes fatal meningoencephalitis in patients with acquired immunodeficiency syndrome (AIDS). This fungal microorganism is an intracellular parasite, and the host defense is usually mediated by cellular immunity. By contrast, the role of polymorphonuclear leukocytes (PMN) is reported to play a limited role. At the end stage of AIDS, the host defense by cellular immunity is no longer expected, but the potential of PMN is not completely excluded. On this background, we examined the activity of human peripheral blood PMN to phagocyte and kill this fungal pathogen. PMN showed the potent phagocytosis and killing against acapsular strain of C. neoformans only when it was opsonized by serum. This activity was strongly enhanced by the addition of either interferon(IFN)-γ or granulocyte macrophage colony-stimulating factor (GM-CSF), but completely abrogated by the capsular polysaccharides of this fungal microorganism, including much of glucuronoxylomannan. The present study re-evaluated the capacity of PMN in the host defense to C. neoformans and provided an implication in the immune-based treatment of this infectious diseases.原著Original Paper