A NEW MUTATION, ALY, THAT INDUCES A GENERALIZED LACK OF LYMPH-NODES ACCOMPANIED BY IMMUNODEFICIENCY IN MICE

We have found a new spontaneous autosomal recessive mutation in mice t hat causes a systemic absence of lymph nodes and Peyer's patches. The name ''alymphoplasia'', with the gene symbol ''aly'', is proposed for this mutant. The spleen of aly/aly mice is devoid of well-defined lymp hoid follicles, and the thymus does not show a clear cortical-medullar y distinction. The mutant homozygotes are deficient in both humoral an d cell-mediated immune functions, and are highly susceptible to infect ions. They have a reduced level of IgM and severely depressed levels o f IgG and IgA in their sera, and do not reject allogeneic skin grafts. However, they have mature T and B cells as determined from their cell surface antigens. The results of bone marrow transplantation experime nts suggest a mesenchymal disorder as a possible cause of the lack of lymph nodes and of immunodeficiency in the aly mouse. The aly mutant m ouse may be a useful animal model of primary immunodeficiency, as are the nu (nude) and scid (severe combined immunodeficiency) mice.