INDUCTION OF CD3-DELTA-EPSILON-OMEGA BY PHORBOL 12-MYRISTATE 13-ACETATE

The effect of phorbol 12-myristate 13-acetate (PMA) on the synthesis, assembly and processing of the components of the T cell receptor (TcR) was studied with special focus on the CD3omega chain. Treatment of th e human leukemic T cell line Jurkat with PMA increased the synthesis o f the Tialpha, CD3gamma and CD3zeta chains two- to threefold and the s ynthesis of Tibeta and CD3deltaepsilonomega complexes five- to sevenfo ld as assessed by metabolic labeling, immunoprecipitation and sodium d odecyl sulfate-polyacrylamide gel electrophoresis followed by scanning densitometry. The amount of total assembled TcR complexes increased a pproximately threefold and the maturation of the TcR was not affected as determined by analysis of oligosaccharide side chain processing in the Golgi apparatus. Activation of Jurkat cells with anti-CD3 monoclon al antibody, calcium ionophore, or mitogenic lectins did not affect th e synthesis of the TcR components. In other cells studied (the human l eukemic T cell line CEM, a panel of variants of the Jurkat T cell line and peripheral blood mononuclear cells) PMA also increased the synthe sis of the TcR components. However, for all cell lines studied the amo unt of TcR complexes expressed on the cell surface was decreased after 16 h of PMA treatment. Based on these results we propose a role of CD 3omega in retention of TcR complexes. From PMA-treated CEM cells more than 50-fold the amount of CD3deltaepsilonomega Complexes was immunopr ecipitated as compared to the amount obtained from untreated Jurkat ce lls, and these observations indicate that the CEM cell line may be a q ualified candidate for purification of CD3omega.