Transferrin-like activity produced by murine malignant T-lymphoma cell lines.

Transferrin has been considered to be an essential requirement for hematopoietic cell proliferation in culture. We have isolated two cloned lymphoma cell lines, SL 12.1 and SL 12.4, which grow and adapt in serum-free medium without added transferrin. Antibody to the transferrin receptor blocks the growth of these cells. We have also demonstrated that transferrin-free conditioned medium from the cells will compete with transferrin for binding. Furthermore, conditioned medium from SL 12.1 and SL 12.4 cells induces and supports exponential growth of a transferrin-dependent lymphoma cell line, SL 12. We conclude that these two transferrin-independent cloned lines produce transferrin-like activity which plays a crucial role for cell proliferation.