Distinct chromosomal abnormalities in murine leukemia virus‐induced T‐ and B‐cell lymphomas

We performed a cytogenetic study on 16 murine mature B‐cell lymphomas and 10 T‐cell lymphomas, using G‐banding techniques. All tumors, with the exception of 3 spontaneous B‐cell tumors, were induced by various slowly transforming murine leukemia virises (MuLV). Metaphases were obtained from primary (10 B‐cell tumors) and first or second transplant generation lymphomas (6 B‐cell and 10 T‐cell tumors), all of which were well characterized with respect to phenotypic, histologic and genotypic features. In the T‐cell tumors we found relatively simple karyotypic abnormalities, including various numerical aberrations, such as trisomy 15, in line with many earlier reports. However, the majority of B‐cell tumors showed a great variety of both structural and numerical chromosomal anomalies. Three B‐cell lymphomas had an apparently normal karyotype. No single cytogenetic abnormality occurred commonly in the B‐cell lymphomas, but some structural abnormalities were found in more than one stemline, in particular, ins (11) (A1; A2) in 3 tumors, and deletions involving the D‐region of chromosome 14 in 3 other lymphomas. These cytogenetic results clearly indicate that the pathogenic mechanisms involved in MuLV‐induced (long latency) B‐cell lymphomagenesis and (short latency) T‐cell lymphomagenesis differ considerably.