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Hofbauer细胞是胎盘巨噬细胞,位于绒毛间质,与胎儿血管相邻,能在母体和胎儿间游走,对入侵胎盘的病原微生物有较强的吞噬作用。其表面含FcγRⅢ受体,包括FcγRⅢA和FcγRⅢB,两者胞外结构域有高度同源性,但FcγRⅢA是一种细胞特异性的糖基化跨膜蛋白,其在细胞表面稳定表达与γ链参与有关;FcγRⅢB不含任何跨膜或细胞质区域,其锚定于细胞膜的糖基磷脂酰肌醇(GPI),其表达与FcR的γ链或ξ链无关。Hofbauer细胞具有肯定的吞噬能力,但不能依赖溶酶体完全溶解杀灭被吞噬的病毒。Hofbauer细胞表面的FcγRⅢ与母体循环的HBsAg-抗-HBsAg等免疫复合物结合引起细胞免疫或淋巴因子的转录,介导HBV宫内感染。
Hofbauer cells are placental macrophages, located in the villus stroma, adjacent to the fetal blood vessels, can walk between the mother and the fetus, the phagocytosis of the pathogenic microorganisms that invade the placenta. Its surface contains FcyRIII receptors, including FcyRIIIA and FcyRIIIB, the two extracellular domains have a high degree of homology, but FcyRIIIA is a cell-specific glycosylated transmembrane protein that is stably expressed on the cell surface with gamma chain involvement ; FcγRⅢB does not contain any transmembrane or cytoplasmic domain, which anchors glycosylphosphatidylinositol (GPI) in the cell membrane, and its expression is independent of the γ chain or ξ chain of FcR. Hofbauer cells have a positive phagocytic capacity, but can not rely on lysosomes to completely lyse the phagocytosed virus. FcyRIII on the surface of Hofbauer cells binds to maternal circulating immune complexes such as HBsAg-anti-HBsAg to induce cellular or lymphokine transcription and mediate HBV intrauterine infection.