Kanbe T, Li R K, Wadsworth E, Calderone R A, Cutler J E
Department of Microbiology, Montana State University, Bozeman 59717.
Infect Immun. 1991 May;59(5):1832-8. doi: 10.1128/iai.59.5.1832-1838.1991.
The complement conversion product C3d binds to a receptor on the cell surface of Candida albicans. While the function of this receptor is still uncertain, we investigated whether it is expressed during a murine infection. Rabbit antiserum raised against purified receptor was used in conjunction with immunofluorescence microscopy and immunocolloidal gold electron microscopy to examine kidney tissue and peritoneal lavages from infected mice for receptor expression by C. albicans in vivo. Specificity of the antiserum was indicated by reactivity with purified receptor (55 to 60 kDa) and with a protein of similar molecular mass from whole hyphal extracts in Western blots (immunoblots). In vitro analysis by immunofluorescence microscopy showed that the antiserum reacted with both yeast and pseudohyphal forms of the organism, but reactivity was strongest with pseudohyphae. Immunocolloidal gold electron microscopy of fungal cells from peritoneal lavages revealed intense staining of mother cells of germinative forms, germ tubes, and pseudohyphae. Staining of the mother cells was heaviest at the innermost layers of the cell wall but only scant on the cell surface. In contrast, staining was observed throughout the cell walls of germ tubes and pseudohyphae. In kidney, expression of the C3d receptor was found primarily on the cell walls of hyphae and pseudohyphae, although some staining was observed in the cytoplasm. These data support that the C3d receptor of C. albicans is expressed in vivo.
补体转化产物C3d与白色念珠菌细胞表面的一种受体结合。虽然该受体的功能仍不确定，但我们研究了它在小鼠感染过程中是否表达。用针对纯化受体产生的兔抗血清结合免疫荧光显微镜和免疫胶体金电子显微镜，检查感染小鼠的肾脏组织和腹腔灌洗液，以检测白色念珠菌在体内的受体表达情况。抗血清的特异性通过与纯化受体（55至60 kDa）以及免疫印迹（蛋白质印迹）中来自全菌丝提取物的相似分子量蛋白质的反应性来表明。免疫荧光显微镜的体外分析表明，抗血清与该生物体的酵母和假菌丝形式均有反应，但与假菌丝的反应性最强。对腹腔灌洗液中的真菌细胞进行免疫胶体金电子显微镜检查发现，发芽形式的母细胞、芽管和假菌丝有强烈染色。母细胞的染色在细胞壁的最内层最重，但在细胞表面仅很少。相比之下，在芽管和假菌丝的整个细胞壁中均观察到染色。在肾脏中，虽然在细胞质中观察到一些染色，但C3d受体的表达主要在菌丝和假菌丝的细胞壁上。这些数据支持白色念珠菌的C3d受体在体内表达。
