Phorbol myristate acetate induction of lymphotoxins from continuous human B lymphoid cell lines in vitro

The phorbol ester 4 beta-phorbol 12-myristate 13-acetate (PMA) was studied for its ability to induce increased lymphotoxin (LT) production from a number of continuous human B lymphoblastoid cell lines that spontaneously release low levels of LT in vitro. A 5-20-fold increase in LT production was seen when all seven of these cell lines were cocultured with 20 ng/ml PMA for 72 h under serum-free conditions in 0.1% lactalbumin hydrolysate. One cell line, GM3104A, was cloned and repeatedly selected to obtain a high-level LT producer in the presence of PMA. This subline, termed IR 3.4, spontaneously released the alpha-LT molecular weight (MW) class; however, upon PMA stimulation it released high levels of alpha and an unrelated beta-LT MW class form. The increased amounts of LT released in the presence of PMA by IR 3.4 lymphoid cells provides a new method for the production of large amounts of alpha-LT for purification from a single cell source for biochemical and functional studies, and indicates that the type of induction signal may influence the type of LT released.