Regulation of TCGF production in T cells. II. Early membrane events after anti-Thy-1 binding by the TCGF-producing T lymphoma EL-4 G-12.

The T cell lymphoma line EL-4 G-12 produces large quantities of TCGF (IL 2) shortly after exposure to anti-Thy-1 and cross-linking reagents. Early surface events that initiate nonconstitutive synthesis and secretion have been examined by fluorescent microscopy, EM analysis, flow cytometry of anti-Thy-1, and measurements of membrane polarization. The data show that anti-Thy-1 binding leads to immediate and rapid endocytosis and shedding of the antibody molecules, but with no change in membrane potential. Cross-linking of the anti-Thy-1 results in stabilization and accumulation of the antibody on the surface, and rapid hyperpolarization. The data suggest that cross-linking of ligand antibody interactions at the surface is a regulatory event involved in initiation of the signal for TCGF synthesis and secretion.