Transferrin support of stimulated lymphocytes.

Transferrin was tested for its ability to replace serum in supporting mitogen and allogeneic cell stimulated human lymphocyte proliferation. Although transferrin, at concentrations greater than 5 microgram/ml, was incapable of completely replacing the serum used to support phytohemagglutinin, Concanavalin A, and pokeweed mitogen, stimulated human lymphocytes, in the absence of serum it significantly augmented the proliferative responses observed for mitogen, yet not allogeneically-stimulated cells. Augmentation is not due to a nonspecific protein effect and appears to be independent of the metal content of transferrin. The mechanism of growth support appears to involve an effect of transferrin following the G1 phase in the initial cell cycle.