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The paper highlights the role of different HLA class II molecules in hepatic and lymphoproliferative HCV-related disorders. HLA molecules have been reviewed, according to an in silico cluster classification, based on the sequence, the biochemical structure of the pockets, and the functional characteristics of the HLA II molecules. Thus, by reducing the complexity of HLA II polymorphism, charateristics that unite different HLA molecules with specific HCV-associated pathologies may be recognized with greater case. Results show that HLA clusters associated with better dlimination of the virus are protective against HCC development, while the same clusters are associated with a higher risk of developing cryoglobulinemic syndrome and the concomitant NHL. These data added further acknowledgements on pathogenetic mechanisms associated with HCV infection. Results also highlight differences of NHL occurring in HCV-positive subjects, with or without a concomitant type II autoimmune cryoglobulinemic syndrome, suggesting that cryoglobulinemic background associated with NHL should be considered in the evaluation of the effectiveness of new therapies in the course of HCV-associated NHLs. [ABSTRACT FROM AUTHOR]

Infectious agents select for host immune responses that destroy infectious nonself yet maintain tolerance to self. Here we propose that retroviruses and other host-antigen associated pathogens (HAAPs) select for the genetic, biochemical, and cell biological properties of alloimmunity, also known as the histocompatibility or tissue rejection response. This hypothesis predicts the major observations regarding histocompatibility responses, including: (i) their existence in animals as diverse as sponges and humans; (ii) extreme polymorphism and balanced allele frequencies at histocompatibility loci, including the human MHC and blood group loci; (iii) the frequency dependent selection of histocompatibility alleles; (iv) the ancient age of many alloantigenic polymorphisms, (v) the high ratio of nonsynonymous mutations to synonymous mutations at histocompatibility loci; (vi) disassortative mating based on MHC alleles; (vii) the inability to explain the existence and continuing selection of histocompatibility alleles by other more conventional biochemical and genetic paradigms; and (viii) the susceptibility of HAAPs, particularly retroviruses such as HIV (human immunodeficiency virus), to histocompatibility reactions in addition, the hypothesis that HAAPs select the forms and molecules of alloimmunity offers simple explanations for the evolution of histocompatibility systems over time, the initial selection of hypervariable immune mechanisms, and the genesis of adaptive immunity. [ABSTRACT FROM AUTHOR]