title: Modulatory effect of aggregating the CD3 molecular complex on T cell activation.
abstract: The role of cross-linking the TCR/CD3 complex in the induction of T cell activation was examined using human peripheral blood T cells and the Jurkat leukemic T cell line. IL-2 production was induced from these cells by pulsing them with mAb to CD3 and costimulating with phorbol myristate acetate (PMA). Cross-linking the anti-CD3 mAb with soluble goat anti-mouse immunoglobulin (GaMIg) markedly inhibited IL-2 production by these cells. Soluble GaMIg did not induce a generalized inhibition of IL-2 production as it was required for responses induced by mAb to class I MHC molecules. In addition, cross-linking anti-CD3 mAb with GaMIg did not inhibit IL-2 production induced by PMA and ionomycin. Inhibition of IL-2 production induced by soluble GaMIg reflected diminished accumulation of mRNA for IL-2. By contrast, immobilized GaMIg was a potent stimulus for IL-2 production by T cells pulsed with anti-CD3 mAb and costimulated with PMA. Cross-linking anti-CD3 with soluble GaMIg induced enhanced aggregation of the ligated molecules, but it did not alter the profile of the change in intracellular calcium induced. To determine whether cross-linking of mAb played a role in inducing IL-2 production as well as in limiting responsiveness, F(ab) fragments were employed. F(ab) fragments of anti-CD3 mAb failed to induce IL-2 production by PMA costimulated Jurkat cells. However, cross-linking of anti-CD3 F(ab)-pulsed Jurkat cells with low concentrations of soluble GaMIg induced IL-2 production in the presence of PMA, whereas higher concentrations suppressed responses. The data indicate that induction of IL-2 production requires aggregation of the TCR/CD3 complex, whereas excessive cross-linking diminishes the induction of IL-2 production. Moreover, the results indicate that various biologic activities of the CD3 molecular complex, including aggregation, signaling capability, and the ability to induce IL-2 gene transcription, are differentially affected by cross-linking.
authors.affiliation: Harold C. Simmons Arthritis Research Center, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas 75235.
authors.forename: H
authors.initials: H
authors.lastname: Gur
authors.forename: M C
authors.initials: MC
authors.lastname: Wacholtz
authors.forename: L S
authors.initials: LS
authors.lastname: Davis
authors.forename: T D
authors.initials: TD
authors.lastname: Geppert
authors.forename: P E
authors.initials: PE
authors.lastname: Lipsky
mesh_terms: D000945:Antigens, Differentiation, T-Lymphocyte / Q000276:immunology*; D017252:CD3 Complex; D002118:Calcium / Q000032:analysis; D002449:Cell Aggregation; D002460:Cell Line / Q000737:chemistry; D005434:Flow Cytometry; D016257:Fura-2; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis / Q000235:genetics; D008213:Lymphocyte Activation / Q000276:immunology*; D016853:Muromonab-CD3 / Q000276:immunology; D012333:RNA, Messenger / Q000032:analysis; D011948:Receptors, Antigen, T-Cell / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D007376:Interleukin-2; D016853:Muromonab-CD3; D012333:RNA, Messenger; D011948:Receptors, Antigen, T-Cell; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium; D016257:Fura-2