Major histocompatability gene genetics

In this section, we shall review the data that have demonstrated genetic restrictions of T-B lymphocyte interactions and of the interactions between macrophages and T lymphocytes. The conclusion we draw from these findings is that the development of functional T cells and the regulatory role of T lymphocytes in immune responses, which appears to be related to control of differentiation processes of other lymphocytes of both T and B classes, is mediated via molecules that are comprised, at least in part, of gene products of the major histocompatibility gene complex expressed on the surface membranes of such cells. 

Hamet, P., Tremblay, J., Malo, D., Kunes, J., Hashimoto, T. (1990b). Genetic hypertension is characterized by the abnormal expression of a gene localized in major histocompatibility complex hsp70. Transplant. Proc. 22,2566-2567. 

MHC class I and II proteins, the presenters of peptides to T cells, were discovered because of their role in transplantation rejection. A tissue transplanted from one person to another or from one mouse to another is usually rejected by the immune system. In contrast, tissues transplanted from one identical twin to another or between mice of an inbred strain are accepted. Genetic analyses revealed that rejection occurs when tissues are transplanted between individuals having different genes in the major histocompatibility complex, a cluster of more than 75 genes playing key roles in immunity. The 3500-kb span of the MHC is nearly the length of the entire E. coli chromosome. The MHC encodes class I proteins (presenters to cytotoxic T cells) and class II proteins (presenters to helper T cells), as well as class III proteins (components of the complement cascade) and many other proteins that play key roles in immunity. 

Immunoglobulin variable region genes are extraordinarily polymorphic, displaying a degree of genetic diversity paralleling that of the major histocompatibility com-... 

Inheritance of HLA characteristics follows a simple Mendelian pattern. The genetic loci controlling the various HLA subregions are contained within the major histocompatibility complex on chromosome 6 (Fig. 1). Each individual inherits one chromosome 6 from one parent and one from the other parent, each chromosome coding for one HLA-A gene, one HLA-B gene, one HLA-C gene, and so on. The HLA-A locus will be occupied by one of the alleles listed in Table 1 under the column headed HLA-A , the HLA-B locus will be occupied by one of the alleles listed under HLA-B , and so on. 

Genetic analyses revealed that rejection occurs when tissues are transplanted between individuals having different genes in the major histocompatibility complex, a cluster of more than 75 genes playing key roles in immunity. 

Haplotypes The genetic constitution of individuals with respect to one member of a pair of aUehc genes, or sets of genes that are closely linked and tend to be inherited together such as those of the major histocompatibility complex. [NIH]... 

Beauchamp, G. K., Yamazaki, K., Bard, J., and Boyse, E. A., 1988, Preweaning experience in the control of mating preferences by genes in the major histocompatibility complex of the mouse, Behav. Genetics 18 537-547. 

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