Characterization of cell markers in type B retroviral-induced thymic lymphomas--I. Surface antigen phenotype and karyotype in developing and primary lymphomas.

CFW/D mice injected neonatally with a type B retrovirus, (DMBA-LV), rapidly develop thymic lymphomas. The present study examined simultaneously the karyotype and the expression of surface antigens on thymocytes from DMBA-LV treated mice at 28, 35 and 42 days of age during the development of lymphomas, and of cells from primary lymphomas. DMBA-LV treatment resulted in disturbances in the proportions of thymic Lyt 1+2-, Lyt 1-2+ and Lyt 1+2+ subpopulations. As a group, virus-treated mice showed a significant decrease in the size of the Lyt 1+2- subpopulation in thymuses during tumor development. However, developing tumors and primary tumors showed individual patterns of alteration in the proportions of thymocyte subpopulations rather than consistent trends for any one thymocyte subpopulation to increase or decrease. Cells with the abnormal chromosome complement, trisomy 15, were present early in the development of tumors and became the predominant karyotype in fully developed tumors. A correlation between the appearance of trisomy 15 and a particular thymocyte surface antigen phenotype was not detected. The results suggest that retrovirus infection disrupts, but does not eliminate the ability of developing thymocytes to form phenotypically distinct subpopulations.