The Friend virus complex contains a helper-independent retrovirus, F- MuLV, and a replication-defective retrovirus, SFFV. Murine erythroleukemia cell lines (MEL) have been isolated previously from the leukemic tissues of mice infected with such stocks of Friend virus complex. Since our laboratory has shown that either F-MuLV or SFFV can induce a lethal erythroproliferative disease, it has been unclear which of the properties of conventional MEL cells were causally related to the infection of these cells by F-MuLV and which properties were related to the infection of these cells by SFFV. In this article, we have focused on the helper-independent component of the Friend virus complex, F-MuLV clone 57, which has recently been purified by molecular cloning. We report a method for the reproducible isolation of a new type of murine erythroleukemia cell that can be isolate from mice infected with F-MuLV clone 57. We have designated these cells as 57 TP- 1, indicating their origin from mice infected with F-MuLV clone 57 and their characteristics as transplantable erythroleukemia cells. Upon subcutaneous, intraperitoneal, or intravenous inoculation of these cells, 57 TP-1 cells grow in the hematopoietic organs of the recipient mice. No subcutaneous or intraperitoneal nodules occur. Both F-MuLV and a Friend MCF virus can be detected in these cells, but no evidence to SFFV can be found.

We describe here the clinical and pathologic features associated with a specific translocation, t(2;13), in alveolar rhabdomyosarcoma. Tumor specimens from 14 patients with a t(2;13)-positive alveolar rhabdomyosarcoma were studied for cytogenetic-clinicopathologic correlations. Three patients had occult primary tumors; nine patients had primary tumors of the trunk (mediastinal, pelvic, or rectal). The presence of the t(2;13) was ascertained from examination of tumor involved bone marrow in ten patients who had widespread metastatic disease at the time of diagnosis. Marrow involvement was so extensive in three cases that they were initially diagnosed as acute leukemia. Response to therapy was poor, with only five patients achieving a complete response. Twelve patients have died of their disease at a median survival time of 6 months from diagnosis and one is living with recurrent disease; only one patient survives free of disease.

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Evidence is presented that at least 17% of microscopically normal bone marrow samples obtained from patients with undifferentiated lymphomas contain occult tumor cells. Of 19 microscopically normal bone marrow samples tested, continuous tumor cell lines were obtained from 4. A tumor cell origin was confirmed by the presence of an 8;14 chromosomal translocation in each case, and HLA typing confirmed the patient origin of the cell line. In two other patients, direct cytogenetic examination of microscopically normal bone marrow samples revealed karyotypes containing 8:14 translocations or a 14q+ chromosome. These findings indicate that undifferentiated lymphomas are often more widespread than is clinically appreciated. The presence of submicroscopic marrow involvement is also of significance to the design and analysis of treatment protocols involving autologous marrow infusion.