Metastatic properties conferred on nonmetastatic tumors by hybridization of spleen b-lymphocytes with plasmacytoma cells

The P3-NSI/1-Ag4-1 (NSI) plasmacytoma, when transplanted sc in syngeneic BALB/c mice, grows locally without forming spontaneous metastases. We tested whether somatic hybridization of the NSI cells with spleen B-lymphocytes would render them metastatic in (C57BL/6 X BALB/c)F₁ mice. We found that the hybridomas thus produced generated spontaneous metastases with distinct organ specificities. Some hybridomas produced metastases in both liver and spleen, whereas others produced metastases in only the liver. Cells derived from spleen-and liver-seeking hybridomas, when transplanted sc, produced tumors that metastasized to both the liver and spleen. Tumor cells derived from spleen metastasis produced, on transplantation, a tumor that generated spleen metastasis of a larger mass than did tumors derived from liver metastases. Cells derived from liver-seeking hybridomas metastasized to only the liver. Similar patterns of organ specificity were observed after iv injection of the hybridoma cells. The spleen seemed to play a determining role in controlling the production of liver metastases by hybridomas that produced both liver and spleen metastases. Such hybridomas did not produce liver metastases when injected into splenectomized recipients. Hybridomas that were only liver-seeking did produce metastases in splenectomized recipients.