We have developed cytotoxic T lymphocyte (CTL) lines specific for two determinants of the maternally transmitted antigen (Mta) and have used these CTL lines to study the tissue distribution of Mta. In previous reports, we characterized CTL lines specific for the Mta.1 determinant. Here, we describe CTL lines specific for the newly defined Mta.2 determinant. Mta.2-specific CTL lines lysed target cells from F1 mice of an NZB (Mtf(β)) mother but did not lyse target cells from reciprocal F1 mice of any Mtf(α) mother. Backcross mice were used as the source of target cells to demonstrate that the Mta.2-specific CTL were H-2 nonrestricted in their recognition. Mta.-1- and Mta.2-specific CTL lines were used to demonstrate Mta expression on lymphoid cells taken from spleen, thymus, lymph nodes, and bone marrow. In addition, Mta was expressed on cultured cell lines of myeloid, epithelial, and mesenchymal origin. Our results suggest that Mta is not a differentiation marker restricted to lymphocyte subpopulations.