Achim C L, Wiley C A
Department of Pathology, University of California, San Diego, La Jolla 92093-0612.
J Neuropathol Exp Neurol. 1992 May;51(3):257-63. doi: 10.1097/00005072-199205000-00003.
Progressive multifocal leukoencephalopathy (PML) is caused by JC virus (JCV) infection of the central nervous system (CNS) in immunosuppressed patients. The immunopathogenesis of this chronic encephalitis is unknown. Because major histocompatibility (MHC) class I and class II antigens are important in modulating the immune response and viral clearance, we examined the tissue expression of MHC molecules in relation to CNS damage and presence of virus. By immunocytochemical staining, both MHC class I and class II antigens were expressed at high levels within PML lesions. Beta-2 microglobulin (beta-2m) was present on endothelial cells and JCV-infected oligodendroglia within the lesions. Also, many astrocytes with bizarre morphology expressed MHC class I antigens. In histologically normal regions of PML brains expression of beta-2m was noted only on endothelial cells. Expression of MHC class II also was focused within demyelinating lesions and was restricted to macrophages/microglia and occasional endothelial cells. When compared to other viral encephalitides (e.g. human immunodeficiency virus) these findings suggest that intra-CNS immune response to JCV is appropriate for antigenic presentation; however, the absence of responsive systemic T-cells may lead to chronic viral infection with progressive neuropathology.
进行性多灶性白质脑病（PML）是由免疫功能低下患者中枢神经系统（CNS）感染JC病毒（JCV）引起的。这种慢性脑炎的免疫发病机制尚不清楚。由于主要组织相容性（MHC）I类和II类抗原在调节免疫反应和病毒清除方面很重要，我们研究了MHC分子的组织表达与CNS损伤及病毒存在的关系。通过免疫细胞化学染色，MHC I类和II类抗原在PML病变内均高水平表达。β2微球蛋白（β2m）存在于病变内的内皮细胞和JCV感染的少突胶质细胞上。此外，许多形态怪异的星形胶质细胞表达MHC I类抗原。在PML脑的组织学正常区域，仅在内皮细胞上观察到β2m的表达。MHC II类的表达也集中在脱髓鞘病变内，且仅限于巨噬细胞/小胶质细胞和偶尔的内皮细胞。与其他病毒性脑炎（如人类免疫缺陷病毒）相比，这些发现表明中枢神经系统内对JCV的免疫反应适合抗原呈递；然而，缺乏反应性的全身T细胞可能导致慢性病毒感染并伴有进行性神经病理学改变。
