Analysis of intrathymic differentiation patterns during the course of AKR leukemogenesis

Thymocytes from AKR mice in different stages of leukemia development were analyzed with the fluorescence-activated cell sorter (FACS) using monoclonal antisera to Lyt-1, Lyt-2, Thy-1.1, H-2K^k, and Ia^k. In addition, the number of cells bearing receptors for peanut agglutinin (PNA) was assessed. The results were correlated with the expression of murine leukemia virus (MuLV) antigen. Thymocytes from late preleukemic and leukemic stages were found to have a phenotype characteristic of a more mature cell population in that there was an increase in the expression of determinants encoded within the K end of H-2^k and Ia^k. This was associated with a decrease in the number of thymocytes bearing receptors for PNA during the leukemic stage. Simultaneously, a shift from a Lyt-1⁺ 2⁺ thymocyte population to cells with varying expressions of Ly antigens was observed. Analysis of Lyt determinants on thymomas indicated that they could arise from cells bearing any of the different possible combinations of Ly phenotypes. The cell surface antigen changes occurred in temporal correlation with an increased expression of MuLV antigens.