Altered pattern of major histocompatibility complex expression in XXXX : @entity5 -specific expression of the nonclassical human leukocyte antigen-G molecule is restricted to @entity1358 while up-regulation of other major histocompatibility complex antigens is primarily distributed in all subtypes of @entity703 .

@entity1637 @entity5 @entity189 @entity1358 @entity982 @entity6393 @entity703
@entity703 represent a heterogeneous group of @entity5 arising from the malignant transformation of presumed diverse cell lineages. We recently demonstrated that @entity5 -specific up-regulation of human @entity6393 , a nonclassical HLA class Ib molecule that might be involved in immune evasion by @entity5 cells, frequently occurs in conventional (clear cell) @entity703 . We here examined whether @entity6393 activation is a common process affecting all types of @entity703 . We analyzed a series of 38 @entity982 -embedded @entity5 including clear cell, papillary, chromophobe, collecting duct @entity189 , and @entity1637 . Seven of 12 (58%) clear cell @entity5 were positive by immunohistochemistry, whereas all of the other subtypes of @entity703 were negative for @entity6393 expression. Developing or adult normal renal tissue were devoid of @entity6393 expression. We also observed that ectopic expression of HLA class II antigens occurs more frequently in @entity1358 than in other subtypes of @entity703 . Moreover, in contrast to the common observation of a down-regulation of major histocompatibility complex class Ia antigens reported in various @entity5 , the concomitant study of the same biopsies for classical HLA class Ia antigen expression revealed a general increase of HLA class Ia expression, regardless of histological subtypes. These results provide evidence for the heterogeneity of major histocompatibility complex expression patterns in @entity703 and support the hypothesis that specific mechanisms underlying the malignant transformation into @entity1358 up-regulate expression of @entity6393 and to a lesser extent HLA class II molecule expression. Considering the immunotolerant role of @entity6393 toward the immune response, these mechanisms may thus provide @entity1358 cells with additional means to escape immune surveillance.
