M1s is not a Single Gene, Allelic System: Different Stimulatory M1s Determinants, are the Products of at Least Two Nonallelic, Unlinked Genes.
NAVAL MEDICAL RESEARCH INST BETHESDA MD
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M1s determinants share with Major Histocompatibility Complex MHC products the unique property of stimulating T cells at extraordinarily high precursor frequencies. The M1s system was originally described as a single locus on chromosome 1, with four alleles, M1sa, M1sb, M1sc, and M1sd, that encode polymorphic cell surface structures. However, the fundamental issues of polymorphism and allelism in the M1s system remain controversial. To clarify these questions, a formal segregation analysis of the genes encoding M1sa and M1sc determinants was carried out by testing the capacity of spleen cells from progeny of M1sa X M1scF1 X M1sb breedings to stimulate responses by unprimed T cells and by M1sa-and M1sc specific cloned T cells. The results of this analysis indicated that the gene encoding M1sa determinants is neither allelic to nor linked to the gene encoding M1sc determinants. Together with previous findings, these results also suggest that another strongly simulatory type, M1sd, in fact results from the independent expression of unlinked M1sa and M1sc gene products. Based on these observations, it is concluded that, contrary to conventional concepts, the stimulatory phenotypes designated as M1sa, Mlsc, and M1sd can be accounted for by the independent expression of the products of at least two linked gene loci.
- Genetic Engineering and Molecular Biology