N-methyl-N-nitrosourea-induced and spontaneous AKR/J thymic lymphomas express distinct differentiation antigen phenotypes

Spontaneous and N-methyl-N-nitrosourea (MNU)-induced AKR/J thymic lymphomas were characterized for expression of several lymphocyte differentiation antigens. The majority (53%) of spontaneous lymphomas expressed both Lyt-2 and L3T4 antigens, similar to the predominant normal thymocyte subset. In contrast, 63% of the thymic lymphomas induced by the chemical carcinogen MNU, expressed an Lyt-2+ L3T4- antigenic profile. Although this profile suggested that MNU-induced lymphomas are phenotypically similar to a mature thymocyte subset, the presence of ThB antigen on Lyt-2+ L3T4- lymphomas did not support this notion. Diagonal gel electrophoresis of ¹²⁵I-labeled membrane extracts and immunoprecipitates revealed that 17 of 29 Lyt-2+ L3T4-MNU-induced lymphomas expressed cell surface T-cell receptor heterodimer components. Northern blot analyses confirmed that the T-cell receptor material was composed of α and β polypeptide chains. The results from this study indicate a distinct origin or differentiation potential of the target cells involved in viral and chemical induced lymphomagenesis of AKR/J mice.