Beta 2-microglobulin deficient mice lack CD4-8+ cytolytic T cells. 1990.

Mice homozygous for a β2-microglobulin gene disruption do not express any detectable β2-m protein. They express little if any functional major histocompatibility complex (MHC) class I antigen on the cell surface yet are fertile and apparently healthy. They show a normal distribution of γδ, CD4 + 8 + and CD4 + 8 - T cells, but have no mature CD4 - 8 + T cells and are defective in CD4 - 8 + T cell-mediated cytotoxicity. Our results strongly support earlier evidence that MHC class I molecules are crucial for positive selection of T cell antigen receptor αβ + CD4 - 8 + T cells in the thymus and call into question the non-immune functions that have been ascribed to MHC class I molecules.