Schirmbeck R, Thoma S, Reimann J
Institute for Medical Microbiology and Immunology, University of Ulm, Germany.
Eur J Immunol. 1997 Dec;27(12):3471-84. doi: 10.1002/eji.1830271248.
Processing of exogenous hepatitis B surface antigen (HBsAg) particles in an endolysosomal compartment generates peptides that bind to the major histocompatibility complex (MHC) class I molecule Ld and are presented to CD8+ cytotoxic T lymphocytes. Surface-associated 'empty' MHC class I molecules associated neither with peptide, nor with beta2-microglobulin (beta2m) are involved in this alternative processing pathway of exogenous antigen for MHC class I-restricted peptide presentation. Here, we demonstrate that internalization of exogenous beta2m is required for endolysosomal generation of presentation-competent, trimeric Ld molecules in cells pulsed with exogenous HBsAg. These data point to a role of endocytosed exogenous beta2m in the endolysosomal assembly of MHC class I molecules that present peptides from endosomally processed, exogenous antigen.
在内溶酶体区室中对外源性乙型肝炎表面抗原（HBsAg）颗粒的加工会产生与主要组织相容性复合体（MHC）I类分子Ld结合的肽，并呈递给CD8 + 细胞毒性T淋巴细胞。既不与肽结合也不与β2-微球蛋白（β2m）结合的表面相关“空”MHC I类分子参与了外源性抗原经MHC I类限制肽呈递的这种替代加工途径。在这里，我们证明，在用外源性HBsAg脉冲处理的细胞中，内溶酶体产生具有呈递能力的三聚体Ld分子需要外源性β2m的内化。这些数据表明内吞的外源性β2m在呈递来自内溶酶体加工的外源性抗原的肽的MHC I类分子的内溶酶体组装中起作用。
