E mu-bcl-2 transgene facilitates spontaneous transformation of early pre-B and immunoglobulin-secreting cells but not T cells.

To assess the lymphoid tumorigenic potential of bcl-2, mice of five independent strains expressing a bcl-2 transgene in B and/or T cells were monitored for disease up to 12 months of age. Lymphoma prevalence was minimal in the T lineage but significant, although low (3-15%), in the B lineage. The principal types of tumors were plasmacytomas secreting immunoglobulin and novel lymphomas that expressed markers such as Sca-1, CD4, Thy-1, CD34 and CD45(B220), consistent with an origin very early in B-lymphoid development. Rearrangement of the c-myc gene was common in the plasmacytomas, implying a synergistic role for myc and bcl-2 in their etiology, but was not detected in the lymphomas.