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Crosses of two independently derived transgenic mice demonstrate functional complementation of the genes encoding heavy (HLA‐B27) and light (beta 2‐microglobulin) chains of HLA class I antigens.

In man a number of diseases are associated with certain alleles of MHC antigens. The most pronounced example is ankylosing spondylitis, which is strongly associated with HLA‐B27. As a first step towards a model system to study the basis of this association, transgenic mice were generated that showed cell surface expression of the HLA‐B27 antigen biochemically indistinguishable from HLA‐B27 antigen expressed on human cells. This result was obtained by crossing two independently derived strains of mice, one of which is transgenic for the HLA‐B27 heavy chain gene, and the other carrying and expressing the human beta 2m gene. Examination of HLA‐B27 and human beta 2m mRNA in various tissues shows the two genes to be expressed in a coordinate fashion. The mRNA levels follow those of endogenous H‐2 Class I genes.