SL/KH strain of mice: a model of spontaneous pre-B-lymphomas.

The SL/Kh strain of mice spontaneously develop two types of non-thymic lymphomas at a high incidence and very short latency. The major type of lymphomas induce systemic lymph node enlargement and hepatosplenomegaly, and the minor type, proliferation predominantly in bone marrow often associated with spinal paralysis. Phenotypes of both types of lymphomas are indistinguishable: they express B220, 6C3, c-kit but not Thy-1.1, Mac-1 and surface Ig. In both types of lymphomas, the immunoglobulin heavy chain gene is found clonally rearranged in the order of VH-D-JH, whereas the light chain gene remains in germ line configuration. About half of the primary lymphomas are dual or oligoclonal in origin. R-PCR also demonstrates expression of lambda 5, RAG-1 and RAG-2, which are specifically associated with pre-B stage lymphocytes. All these observations indicate that both types of the SL/Kh lymphomas are pre-B-lymphomas.