The Biology Project: Immunology

Introduction to Immunology

Problem 12. HLA genetic diversity

Human HLA genes (equivalent to MHC genes in mice) have many alleles, and no two individuals have identical alleles at all gene loci. Which of the following are consequences of this genetic diversity?

A. Maximizes the kinds of pathogens that can be recognized and eliminated by an immune response within a population
B. Transplanted organs can be rejected
C. Females mice prefer to mate with males having different alleles at MHC gene loci

All of the above

The MHC alleles called H2 in mice and HLA in humans regulate our immune response to antigens. The cell surface glycoproteins bind to small fractions of pathogens and carry these fragments to the cell surface where they can be detected by T cells. Diversity in the MHC molecules means a wider potential immune response to pathogens, and thus is a survival advantage. Normally, our immune system responds to our own MHC molecules with pathogen fragments, but the presence of foreign MHC molecules on transplanted tissues can lead to a massive immune response and tissue rejection. Finally, studies on many species show that mating preference and odor is somehow related to MHC alleles. The immune advantage of MHC diversity is apparently selected for during mating.


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