The capsule of cryptococcus neoformans passively inhibits phagocytosis of the yeast by macrophages.
The capsule of cryptococcus neoformans passively inhibits phagocytosis of the yeast by macrophages.
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DOI：
10.4049/jimmunol.130.4.1994
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发表时间：
1982-10
影响因子：
4.4
通讯作者：
T. Kozel;E. Gotschlich
中科院分区：
文献类型：
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作者：
T. Kozel;E. Gotschlich
我们研究了隐球菌荚膜多糖抑制巨噬细胞吞噬新生隐球菌的机制。O-乙酰基和羧基是血清型D多糖的主要结构特征。血清型D荚膜多糖或包封的完整隐球菌通过用0.1 M NaOH碱性水解进行脱-O-乙酰化。通过用1-乙基-3（3-二甲基氨基丙基）碳二亚胺处理，然后用硼氢化钠还原来还原羧基。脱-O-乙酰化或羧基还原的多糖具有吞噬抑制特性，与未处理的多糖没有明显不同;因此，O-乙酰基和羧基都不是必不可少的吞噬抑制决定因素。这些非抑制组特异性的抗血清通过用脱-O-乙酰化或羧基还原的全细胞吸附隐球菌抗血清以产生分别富含O-乙酰基和羧基特异性抗体的抗血清而获得。这些吸附的抗血清显示调理活性的未处理的酵母，这是类似于未吸附的抗血清，当这些抗血清进行比较，在相同水平的沉淀抗体。我们还检测了调理素IgG的Fab'片段减少调理酵母所需的抗囊IgG的量的能力。Fab'片段和未消化的IgG在调理作用中没有协同作用。这些结果与抑制吞噬作用的被动机制一致。囊不直接调节吞噬功能，而是呈现不被吞噬细胞识别的表面。这种识别的缺乏通过调理对胶囊上的任何表面决定簇具有特异性的抗体来纠正。
We examined the mechanism by which cryptococcal capsular polysaccharide inhibits phagocytosis of Cryptococcus neoformans by macrophages. O-Acetyl and carboxyl groups are major structural features of serotype D polysaccharide. Serotype D capsular polysaccharide or encapsulated whole cryptococci were de-O-acetylated by alkaline hydrolysis with 0.1 M NaOH. Carboxyl groups were reduced by treatment with 1-ethyl-3(3-dimethylaminopropyl)carbodiimide followed by reduction with sodium borohydride. De-O-acetylated or carboxyl-reduced polysaccharides had phagocytosis-inhibiting properties that did not differ appreciably from the untreated polysaccharide; thus, neither the O-acetyl nor the carboxyl groups were essential phagocytosis-inhibiting determinants. Antiserum specific for these noninhibitory groups was obtained by adsorption of cryptococcal antiserum with de-O-acetylated or carboxyl-reduced whole cells to produce antiserum enriched respectively with antibody specific for the O-acetyl and carboxyl groups. These adsorbed antisera showed opsonic activity for the untreated yeast that was similar to the unadsorbed antiserum when these antisera were compared at identical levels of precipitating antibody. We also examined the ability of Fab' fragments of opsonic IgG to reduce the amount of anticapsular IgG needed to opsonize the yeast. No synergy was noted between Fab' fragments and undigested IgG in opsonization. These results are consistent with a passive mechanism for inhibition of phagocytosis. The capsule does not directly modulate phagocytic function, but instead, presents a surface that is not recognized by the phagocyte. This absence of recognition is corrected by opsonizing antibody specific for any surface determinant on the capsule.