The synthesis of folate-binding protein in lymphocytes during transformation.

The blast transformation of human lymphocytes exposed to phytohaemagglutinin was associated with an increase in the intracellular concentration of a folate-binding protein. The protein was measured by a radioimmunoassay and by immunofluorescent microscopy using an antiserum raised against purified folate-binding protein prepared from chronic myelogenous leukaemia cells. Because it has been previously shown that protein-bound folate cannot function as a cofactor or substrate, the synthesis of this binder during some phase of the replicative cycle may serve to modulate folate-dependent RNA and DNA synthesis by controlling the concentration of free folate.