Allospecific Cytotoxic T Cells Generated from β2m−/−Mice in Primary MLC: Analysis of Activation Requirements, Specificity, and Phenotype

It has been demonstrated by several investigators that β2m−/−knockout mice are deficient in the expression of MHC Class I molecules but can nevertheless generate CD8+allospecific cytotoxic T cells following vigorousin vivopriming. We demonstrate here thatin vivopriming is not necessary to generate MHC Class I allospecific CTL from β2m−/−mice. When splenocytes from naive unprimed β2m−/−mice were provided exogenous cytokines in MHC Class I disparate primary MLC, allospecific cytolytic effectors were generated. β2m−/−MHC Class I allospecific CTL that were CD3+and Thy1.2+were otherwise heterogeneous in phenotype, including CD8+, CD4+, CD8−CD4−, TCRαβ+, and TCRγδ+T cells. This phenotypic variability of β2m−/−CTL generated in primary MLC reveals the diversity of CTL precursors that developin vivoin the absence of MHC Class I.