Detection of Cell-Mediated Lympholysis Determinants Encoded by the I-A and I-E Genes on Ultraviolet-Irradiated Spleen Cells

We have analysed the effects of ultraviolet (UV) irradiation on the expression, by normal splenic cell populations, of cell-mediated lympholysis determinants encoded by the I-A and I-E genes of the H-2 complex. Cytotoxic T lymphocytes specific for class II antigens could be generated from unprimed responder mice when stimulated with UV-treated cells from I-A-and/or I-E-congenic mice in the presence of interleukin 2-containing medium. A cytotoxic T-cell line specific for I-Ek antigens was obtained and maintained upon stimulation with UV-irradiated spleen cells. Secondary Ia-specific responses were obtained with UV-irradiated stimulators in the absence of added soluble factors. The results show that the failure of UV-irradiated cells to stimulate primary cytotoxic T-cell responses is not due to a selective destruction of class II antigens but rather to the inactivation of a still undefined function of Ia-positive cells, other than interleukin-1 production, involved in the establishment of high-affinity interactions between the responding T helper cells and the stimulator cells.