The theta antigen of mice and its analog in rats

Citation

Douglas, Tommy C. (1974) The theta antigen of mice and its analog in rats. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/M2MS-4902. https://resolver.caltech.edu/CaltechETD:etd-10252005-102646

Abstract

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The Thy-1 antigen is a normal cell surface component of mouse fibroblasts, brain cells, and thymus-derived lymphocytes (T-cells). This thesis presents the results of genetic, phylogenetic, developmental, and physiological studies of this antigen and its rat analog, [theta]-R.

The Thy-1 locus, which controls the expression of the Thy-1 antigen, was previously shown to be located on Chromosome 9 of the mouse. It has been mapped more precisely by following its segregation relative to the linked markers Trf and Mod-1. This group of genes will probably be useful in future genetic studies of this chromosome.

Sublines of the inbred AKR mouse strain have been typed for a variety of genetic markers. Differences were found in Thy-1 antigen, cytoplasmic malic enzyme, kidney esterase-3, principal urinary protein, expression of Murine Leukemia Virus-gs antigen and incidence of leukemias. Those sublines homozygous for [...] appeared to show an increased susceptibility to spontaneous leukemia as compared with those homozygous for [...].

Thymocytes from rats of 13 different inbred and 2 random-bred populations were found to express an antigen indistinguishable from Thy-l.l. At birth little or none of this antigen was present in rat brain. Soon afterward an approximately logarithmic increase in antigen expression began. This continued until about day 20 when the adult level, which exceeded that in neonatal brain by more than 100-fold, was reached.

Absorption and complement-mediated cytotoxicity tests failed to detect the Thy-l.l-like antigen ([theta]-R) on rat lymph node, spleen, or bone marrow cells. Pretreatment of immune rat peritoneal exudate cells with anti-Thy-1.1 antibodies in the presence of complement did not abolish their ability to kill tumor cells in vitro. These results suggest that the expression of the [theta]-R antigen by rat thymus-derived lymphocytes not only decreases during maturation, as is the case in the mouse, but ceases altogether.

Contrary to this conclusion is the finding that [...]-homozygous mice immunized against rat peripheral lymphocytes made antibodies directed against Thy-1.1. It therefore appears that small amounts of the [theta]-R antigen are in fact expressed by rat peripheral thymus-derived lymphocytes.

Following suitable absorptions, antisera prepared in rats against thymocytes from mice homozygous for the [...] allele could be rendered specific for Thy-1.2. Antibodies directed against one or more other mouse alloantigens could also be detected in these antisera.

The relationship of these results to the current literature on Thy-1 is discussed.

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