Lymphoma in the BB/E rat: c-myc translocation identified.

In a prospective necropsy study involving 257 animals in the BB rat colony in Edinburgh, there was an increased incidence of lymphoma (average 10.9 per cent in all three subgroups: 8 per cent in diabetic, 20 per cent in non-diabetic diabetes-prone, and 3.2 per cent in diabetes-resistant rats). The incidence was significantly increased (P < 0.05) in the non-diabetic diabetes-prone subgroup. These results differ markedly from previous results and indicate that the relationship between lymphoma and diabetes is more complex than previously suggested. All the lymphomas bar one involved the ileocaecal nodes and were classified as immunoblastic lymphomas of B-cell origin. There was a striking resemblance both in tissue distribution and in histological classification to the lymphoma seen in the established B-cell lymphoma model, the LOUVAIN rat. Southern blot analysis carried out on the BB rat lymphomas revealed a translocation of variable length involving the c-myc oncogene. Such a translocation has not been demonstrated in the BB rat before.