Stockinger B, Hausmann B
National Institute for Medical Research, Department of Molecular Immunology, Mill Hill, London, UK.
Int Immunol. 1994 Feb;6(2):247-54. doi: 10.1093/intimm/6.2.247.
C5, the fifth component of complement, is a circulating self protein which induces complete tolerance in MHC class II restricted, CD4+ T cells due to the presentation of C5 taken up from plasma. Functional recognition of in vivo processed C5 was monitored by activation of C5 specific T cell hybrids cultured with antigen presenting cells (APC) from C5 expressing mice. Dendritic cells isolated from various tissues (spleen, thymus, skin) proved to be the most efficient APC, since 10- to 50-fold more macrophages and at least 100- to 500-fold more B cells were needed to achieve similar T cell activation. Stimulatory C5 peptide--class II complexes generated in vivo were retained on the surface of dendritic cells but not on macrophages and B cells upon prolonged culture. Dendritic cells but not macrophages from thymus presented in vivo processed C5. Taken together these findings emphasize the crucial role dendritic cells play for recognition of soluble self proteins by MHC class II restricted T cells.
补体的第五成分C5是一种循环自身蛋白，由于从血浆中摄取的C5的呈递，它能诱导MHC II类限制性CD4+ T细胞产生完全耐受性。通过用来自表达C5的小鼠的抗原呈递细胞（APC）培养C5特异性T细胞杂交瘤的激活来监测体内加工的C5的功能识别。从各种组织（脾脏、胸腺、皮肤）分离的树突状细胞被证明是最有效的APC，因为需要多10至50倍的巨噬细胞和至少多100至500倍的B细胞才能实现类似的T细胞激活。体内产生的刺激性C5肽-II类复合物在长期培养后保留在树突状细胞表面，而不在巨噬细胞和B细胞表面。胸腺中的树突状细胞而非巨噬细胞呈递体内加工的C5。这些发现共同强调了树突状细胞在MHC II类限制性T细胞识别可溶性自身蛋白中所起的关键作用。
