title: Induction of nonspecific cytotoxicity by monoclonal anti-T3 antibodies.
abstract: The effects of monoclonal anti-T3 antibodies on the effector phase of cytotoxic T lymphocytes (CTL) were studied with respect to antigen-specific and antigen-nonspecific lysis of different target cells. Anti-T3 antibodies inhibited the antigen-specific lysis by CTL generated in mixed lymphocyte cultures (MLC), but they concomitantly augmented the nonspecific killing of third-party cells such as the cell lines Daudi, Raji, and K562. This nonspecific cytotoxicity was induced by various anti-T3 antibodies, whereas antibodies reactive with other antigens expressed on the cytotoxic effector cells lacked any such activity. Anti-T3 antibodies induced nonspecific cytotoxicity only when activated T cells, obtained by primary MLC, by repeated restimulation, or after cloning, were used. The antibodies had no effect on unstimulated peripheral T lymphocytes or thymocytes. The inhibition of the antigen-specific lysis and the induction of nonspecific lysis by anti-T3 was dose dependent, and both effects occurred at the same concentration range of anti-T3. F(ab')2 fragments of anti-T3 inhibited the specific lysis but were not able to induce cytotoxic activity, indicating that this induction is an Fc-dependent process. When different target cells were tested, only Fc receptor-positive cells were susceptible for this nonspecific cytotoxicity. Thus, anti-T3 antibodies have a dual effect on effector CTL: they inhibit antigen-specific lysis and concomitantly induce nonspecific lysis in an Fc-dependent way.
authors.forename: J F
authors.initials: JF
authors.lastname: Leeuwenberg
authors.forename: H
authors.initials: H
authors.lastname: Spits
authors.forename: W J
authors.initials: WJ
authors.lastname: Tax
authors.forename: P J
authors.initials: PJ
authors.lastname: Capel
mesh_terms: D000911:Antibodies, Monoclonal / Q000502:physiology*; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000276:immunology*; D001667:Binding, Competitive; D002460:Cell Line; D002999:Clone Cells / Q000276:immunology; D003602:Cytotoxicity, Immunologic; D004306:Dose-Response Relationship, Immunologic; D000939:Epitopes; D006801:Humans; D008213:Lymphocyte Activation; D011961:Receptors, Fc / Q000502:physiology; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D000939:Epitopes; D011961:Receptors, Fc