title: Monoclonal antibodies to murine gamma-interferon which differentially modulate macrophage activation and antiviral activity.
abstract: Four monoclonal IgG antibodies to purified, recombinant murine gamma-interferon (rIFN-gamma) have been produced by fusion of immune hamster splenocytes with HAT-sensitive murine myeloma cells. Specificity was confirmed either with an enzyme-linked immunosorbent assay (ELISA) that used immobilized rIFN-gamma or with a radioimmunoassay that employed soluble 125I-rIFN-gamma and heat-killed, fixed Staphylococcus aureus-bearing Protein A. Competition binding experiments suggested that the monoclonal antibodies (MoAb) displayed two distinct epitope specificities: one displayed by H1 and H2, and the other displayed by H21 and H22. By using murine-human recombinant IFN-gamma hybrid molecules, the H1/H2 epitope was shown to depend on the amino-terminus of IFN-gamma, whereas the H21/H22 epitope was formed by the carboxy-terminal amino acid sequence. The MoAb also reacted with natural IFN-gamma. When bound to a surface, all four MoAb, but not normal hamster IgG, removed 100% of the antiviral and MAF activities present in supernatants of cultures of the murine 24/G1 T cell hybridoma. In free solution, all four antibodies inhibited IFN-gamma dependent antiviral activity, but with different efficiencies. Soluble H21/H22 also blocked all of the 24/G1-derived activity that induces nonspecific tumoricidal activity in macrophages (MAF) while H1/H2 enhanced MAF activity. The differential inhibitory or enhancing activities of H21 or H1 reflected their ability to inhibit or enhance binding of 125I-rIFN-gamma to macrophages, respectively. Soluble H21/H22 and solid-phase H1/H2 inhibited 100% of the MAF, microbicidal, and Ia-inducing activities from lymphokine preparations produced by mitogen stimulation of normal murine splenic cells. These results help to establish definitive structure-function relationships for the IFN-gamma molecule, and indicate that IFN-gamma is the primary lymphokine responsible for inducing nonspecific tumoricidal activity and Ia antigen expression, and for enhancing microbicidal activity in macrophages.
authors.forename: R D
authors.initials: RD
authors.lastname: Schreiber
authors.forename: L J
authors.initials: LJ
authors.lastname: Hicks
authors.forename: A
authors.initials: A
authors.lastname: Celada
authors.forename: N A
authors.initials: NA
authors.lastname: Buchmeier
authors.forename: P W
authors.initials: PW
authors.lastname: Gray
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000502:physiology*; D000918:Antibody Specificity; D000937:Antigen-Antibody Reactions; D000942:Antigens, Bacterial / Q000276:immunology / Q000302:isolation & purification; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000032:analysis; D006168:Guinea Pigs; D006801:Humans; D007106:Immune Sera / Q000494:pharmacology; D007371:Interferon-gamma / Q000096:biosynthesis / Q000276:immunology* / Q000502:physiology; D008213:Lymphocyte Activation; D008222:Lymphokines / Q000096:biosynthesis / Q000502:physiology; D008262:Macrophage Activation; D016215:Macrophage-Activating Factors; D051379:Mice; D011817:Rabbits; D051381:Rats; D011917:Rats, Inbred Lew; D013154:Spleen / Q000166:cytology
chemical_list: D000911:Antibodies, Monoclonal; D000942:Antigens, Bacterial; D000939:Epitopes; D007106:Immune Sera; D008222:Lymphokines; D016215:Macrophage-Activating Factors; D007371:Interferon-gamma