Monoclonal antibodies to murine gamma-interferon which differentially modulate macrophage activation and antiviral activity

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.     

Protein kinase C in tumoricidal activation of mouse macrophage cell lines

A potential role of protein kinase C (PKC) in lipopolysaccharide- (LPS-) induced tumoricidal activation of macrophages was investigated by using two mouse macrophage cell lines (P388D1 and J774). J774 cells are stimulated by LPS to kill target P815 mastocytoma cells, whereas P388D1 cells fail to develop such an ability. Pretreatment of J774 cells with H-7 or phorbol myristate acetate resulted in a significant inhibition of LPS-induced cytotoxicity, whereas pretreatment with H-8, ML-7, HA1004, or W-7 did not. Since these results suggested a critical role of PKC in the activation process, the properties of PKC in the two cell lines were compared. Western blotting with rabbit antiserum specific for the PKC beta regulatory domain allowed detection of a protein of 79 kilodaltons (kDa) in the detergent lysates of both cell lines that were not stimulated by LPS. However, LPS treatment resulted in the appearance of a second protein of 40 kDa only in J774 cells and not in P388D1 cells. Furthermore, two forms of protein kinase (one basic and the other acidic) were identified in the cytosol of J774 cells by HPLC on DEAE-5PW, whereas only the basic form was found in P388D1 cells. On the basis of the response of the basic and acidic form protein kinases to phosphatidylserine (PS), diolein, and Ca2+, the basic form was found to contain both regulatory and catalytic domains of PKC, whereas the acidic form was suggested to represent the PKC catalytic domain.(ABSTRACT TRUNCATED AT 250 WORDS)     

Monoclonal antibodies against T cell differentiation antigens initiate stimulation of monocyte/macrophage oxidative metabolism

Within the first minute after incubation with the mouse anti-human T cell orthoclone monoclonal antibodies OKT3, OKT4, and OKT8, and in the absence of complement, human monocytes generate a burst of highly reactive oxygen metabolites as detected by a luminol-dependent photometric chemiluminescence (CL) assay. The kinetics of the CL responses to these antibodies are identical to that induced by OKM1, the monoclonal antibody to human monocytes and granulocytes. With regard to CL response intensities, OKM1 induces the maximal response and those of OKT3, OKT4, and OKT8 closely reflect the proportion of T cell subsets recognized by these antibodies in peripheral blood. This reaction is also observed when monoclonal antibodies against mouse Lyt surface determinants (Lyt-1 and Lyt-2) and Thy-1 antigen are tested against murine spleen cells. This murine model was further used to investigate the specificity and the mechanism of this reaction. It was demonstrated that the CL response is Lyt antigen specific, occurs upon addition of monoclonal IgG but not IgM antibodies, requires the concomitant presence of CL-producing cells (CLPC) (promonocytes, monocytes, macrophages, and/or granulocytes) and of fully differentiated T cells, and lastly, is mediated via a T cell opsonization process. Selective blockade of bone marrow cell Fc receptors (FcR II) with monoclonal anti-mouse FcR II antibody inhibits the CL response to IgG2b anti-T cell antibody-coated thymocytes and thus strongly suggests that the stimulation of CLPC oxidative metabolism in this model results from the binding of opsonized T cells to plasma membrane Fc receptors. These observations lend additional support to increasing evidence that the initiation of effector functions by monoclonal anti-T cell antibodies may be strictly dependent upon the presence of monocytes and/or macrophages.     

Monoclonal antibodies directed against mouse macrophages in different stages of activation for tumor cytotoxicity

Three rat monoclonal antibodies against mouse peritoneal macrophages in different stages of activation were produced and characterized. One of these (AcM.1) bound to activated macrophages induced by pyran and Corynebacterium parvum, but not to resident and thioglycollate medium- (TGC) or proteose peptone- (PP) elicited macrophages. On the contrary, the antigen identified by MM9 monoclonal antibody was expressed only on resident and TGC- or PP-elicited macrophages. WE15 monoclonal antibody, on the other hand, reacted with all of the macrophages described above. In the assay for function, AcM.1 and WE15 monoclonal antibodies in the presence of complement (C) abolished the capacity of activated macrophages induced by pyran or C. parvum but not the capacity of killer T cells and natural killer (NK) cells to kill tumor target cells. On the other hand, MM9 and anti-Thy-1.2 monoclonal antibodies in the presence of C, as expected, did not affect the cytotoxicity of activated macrophages. However, none of the four monoclonal antibodies in the absence of C had any blocking effect on macrophage-mediated cytotoxicity. AcM.1 antibody reacted with two polypeptides with m.w. of 70,000 and 45,000 on pyran-activated macrophages; however, the antigens recognized by WE15 and MM9 have not been determined yet. These results indicate that the three rat monoclonal antibodies define different antigens present on macrophages at different stages of activation for tumor cytotoxicity, and that these antibodies should prove to be useful probes for analyzing the mechanism of activation of macrophages for tumor cytotoxicity.     

Monoclonal antibodies that inhibit activation and proliferation of lymphocytes. I. Expression of the antigen on monocytes and activated lymphocytes

It has been shown previously that HBJ127 and HBJ98 monoclonal antibodies raised against a human bladder cancer cell line, and B3 monoclonal antibody against a rat bladder cancer cell line recognized unique cell surface antigens abundant in proliferating cells of the corresponding species. Distribution of the antigens and kinetics of the appearance on human and rat lymphoid cells were examined by means of flow cytometry. Rat macrophages and human peripheral blood monocytes were stained strongly with the B3 and HBJ127 monoclonal antibodies, respectively. With regard to lymphocytes, the expression of the B3-defined antigen on rat lymphocytes was found to have a negative correlation with the maturation of the lymphocytes; the antigen was most abundant in bone marrow cells, less abundant in thymocytes, and least abundant in spleen, lymph node, and peripheral blood lymphocytes. Similarly, the HBJ127-defined antigen on human peripheral lymphocytes was negligible. On activation with Con A or alloantigens, however, both rat and human T lymphocytes did strongly express these antigens. Activation of human or rat B cells with lipopolysaccharide also resulted in the augmented expression of these antigens. Kinetics studies revealed that the antigen expression was readily manifested within 12 hr on activation of rat or human T cells with Con A, was augmented progressively with culture time, and reached a plateau within 36 hr. This somewhat earlier appearance of these antigens apparently preceded the manifestations of the IL 2 receptor (Tac antigen) and the augmented DNA synthesis. The B3-defined antigen on Con A-stimulated T cells was more rich on the lymphocytes in S and G2/M phases than those in G1 phase, and the expression was not significantly affected by the addition of hydroxyurea, but was moderately inhibited by the addition of sodium butylate. These results suggest that the appearance and expression of the B3-defined antigen and probably also those of the HBJ127/HBJ98-defined antigen are correlated with lymphocyte activation and subsequent progression through the cell cycle.     

Monoclonal antibodies that inhibit IgE binding

Four monoclonal antibodies were produced that inhibit IgE binding to the high affinity IgE receptor (Fc epsilon R) on rat basophilic leukemia cells. The four monoclonal antibodies (mAb) fall into two groups. The first group was comprised of 3 antibodies (mAb BC4, mAb CD3, and mAb CA5) that reacted with the Fc epsilon R at epitopes close or identical to the IgE-binding site. With 125I-labeled antibodies there was reciprocal cross-inhibition between the antibodies and IgE. The antibodies activated both RBL-2H3 cells and normal rat mast cells for histamine release. The 3 antibodies immunoprecipitated the previously described alpha, beta, and gamma components of the receptor. The number of radiolabeled Fab fragments of 2 of these antibodies bound per cell was similar or equal to the number of IgE receptors. In contrast, the mAb BC4 Fab bound to 2.1 +/- 0.4 times the number of IgE receptor sites. Therefore, the portion of the Fc epsilon R exposed on the cell surface must have two identical epitopes and an axis of symmetry. These 3 monoclonal antibodies recognize different but closely related epitopes in the IgE-binding region of the Fc epsilon R. The fourth monoclonal antibody (mAb AA4) had different characteristics. In cross-inhibition studies, IgE and the other 3 monoclonals did not inhibit the binding of this 125I-labeled monoclonal antibody. The number of molecules of this antibody bound per cell was approximately 14-fold greater than the Fc epsilon R number. This monoclonal antibody caused the inhibition of histamine release and it appears to bind to several cell components.     

Monoclonal antibodies that inhibit activation of transcription by the Escherichia coli cyclic AMP receptor protein

The properties of the two monoclonal antibodies which were found to inhibit cyclic AMP receptor protein (CRP)-stimulated abortive initiation without affecting cAMP binding (Li, X.-M., and Krakow, J. S. (1986) J. Biol. Chem. 260, 4378-4383) have been characterized. Binding of monoclonal antibody (mAb) 66C3 to CRP is stimulated by cAMP while CRP binding by mAb 63B2 is not affected by cAMP. Binding of cAMP-CRP-mAb 63B2 to the lac P+ DNA is completely inhibited. Whereas cAMP-CRP forms a stable complex only at the CRP site 1 of the lac P+ promoter fragment, cAMP-CRP-mAb 66C3 binds to both site 1 and site 2. DNase I footprinting using a HpaII fragment carrying only the lac site 2 does not show any protection by cAMP-CRP-mAb 66C3. With the lac L8UV5 promoter, binding is not seen at either the L8 site 1 or the unaltered site 2. In the presence of 25% glycerol, cAMP-CRP-mAb 66C3 binds to both L8 site 1 and site 2. RNA polymerase is unable to bind to the cAMP-CRP-mAb 66C3-lac P+ complex. In the presence of RNA polymerase, cAMP-CRP forms a stable complex at the L8 site 1, the subsequent addition of mAb 66C3 results in the release of CRP. The CRP present in the lac P+ open promoter complex is partially resistant to subsequent incubation with mAb 66C3. The results provide further evidence regarding possible contacts between CRP and RNA polymerase involved in establishing the open promoter complex.     

Prostaglandin E2 does not inhibit tumoricidal activity of mouse macrophages against adherent tumor cells

We determined whether endogenously produced PGE2 can down-regulate the tumoricidal properties of macrophages by a negative feedback mechanism. Peritoneal exudate macrophages or resident peritoneal macrophages of mice were incubated in medium (control) or in medium containing IFN-gamma and LPS. Activated macrophages were highly tumoricidal against syngeneic melanoma cells and secreted high levels of PGE2. Treatment with indomethacin or diclofenac sodium (voltaren) completely inhibited the production and secretion of PGE2 but not the tumoricidal activity of activated macrophages measured either immediately after activation or 1 to 3 days thereafter. Finally, the addition of exogenous PGE2 did not alter the ability of peritoneal exudate macrophages to respond to IFN-gamma or of LPS to produce high levels of tumor cell lysis. Collectively, these results show that PGE2 produced by activated macrophages is not a down-regulator of their tumoricidal activity against adherent tumor cells.     

Monoclonal antibodies against calcitonin

Summary Twenty-seven monoclonal antibodies (MAbs) to synthetic human calcitonin (CT) were characterized for their reactivities with human CT peptide fragments by dotblot analysis on nitrocellulose paper. Most of the antibodies bound to the C-terminus and fewer to the mid-region of CT. We have studied thyroid tissue specimens from several animal species after fixation in paraformaldehyde-, glutaraldehyde-or picric acid-containing mixtures and cryostat sectioning or embedment in paraffin or plastic (Epon 812 or Lowicryl 4KM) using this panel of MAbs. The site of antigen-antibody reaction was revealed either by immunoperoxidase, immunoalkaline phosphatase or by silver-enhanced immunogold staining methods. All MAbs were able to localize CT in human, rat and mouse thyroid C cells. Nineteen MAbs recognizing synthetic salmon CT and synthetic [Asu^1,7]-eel CT by bot-blot, reacted with chicken ultimobranchial body C cells. One MAb recognizing native porcine CT by dot-blot, stained C cells in hog thyroid. Immunopositivity was confined to the cytoplasm and ultrastructural immunogold labelling demonstrated that cytoplasmic secretory granules were stained. Surgical specimens from human medullary thyroid carcinoma were also analysed for the presence of CT and a variable number of positive cells was found. Furthermore, Congo red-positive areas were shown to react with the MAbs. All conventional staining and immunoabsorption controls were negative. Hence, these MAbs may be suitable for use in routine immunopathological diagnosis of CT-producing tumors and for immunocytochemical localization of the three major CT variants in different animal species.Presented in part at the International Symposium on Biotechnology in Clinical Medicine, BIOTECH RIA '87, 13th–15th April, 1987, Rome, Italy     

Monoclonal antibodies ICO-20 against human thymocyte antigen T10

Monoclonal antibodies (Mab) Ig G2a isotypes reacting in indirect immunofluorescence assay with 68.7 +/- 4.1% of thymocytes, 7% of T-cells and not determining the antigen on other blood cells were obtained. Mab ICO-20 reacted in complement-dependent cytotoxic test. The antigen was expressed on colony-forming cells of granulocyte-macrophage row. Mab ICO-20 reaction with 100% of thymocytes was defined by flow cytometry. Antigen molecular mass is 45000 Dalton. The antigen was expressed on blast cells of patients with ALL and AML. Mab ICO-20 reaction was more more often with T-cell ALL.     

Monoclonal antibodies against bacteria

Highlights are presented of most recent work in which monoclonal antibodies have been instrumental in the study of bacteria and their products. Topics summarized pertain to human and veterinary medicines, dentistry, phytopathology, ichthyology, and bacterial ecophysiology, differentiation, evolution and methanogenic biotechnology.     

Macrophage activation for tumor cytotoxicity: genetic variation in macrophage tumoricidal capacity among mouse strains.

Development of activated tumoricidal macrophages following Mycobacterium bovis, strain BCG infection in vivo or lymphokine treatment in vitro was examined with more than 20 mouse strains. Peritoneal macrophages from 8 of 22 strains failed to develop tumoricidal capacity by 7 days after intraperitoneal BCG infection. Macrophages from 6 of 6 in vivo nonresponder strains also failed to develop tumoricidal capacity after in vitro treatment with lymphokines. Identification of nonresponder mouse strains should provide a useful resource for analysis of intermediary reactions in macrophage activation.     

Monoclonal antibodies against tryptophanyl-tRNA-synthetase

Monoclonal antibodies designated as Am1 and Am2 were prepared against purified beef pancreas tryptophanyl-tRNA synthetase (EC 6.1.1.2). Both antibodies were able to bind the native enzyme in a solid-phase assay and to precipitate enzyme activity in immune complexes. Am2 inhibited the tryptophanyl-tRNA synthetase activity in ATP-[32P]pyrophosphate exchange and in tRNATrp aminoacylation reactions; Am1 had no influence on both the enzyme activity and the inhibiting action of Am2. Only Am2, not Am1, bound elastase-modified form of the enzyme which consists of two subunits shortened by 20 000 daltons from the N-end of the molecule. These results were interpreted as an evidence for non-overlapping of Am1 and Am2 antigenic determinants along the polypeptide chains of the enzyme.     

Monoclonal antibodies against ovalbumin

Fusion of cells of the NS-1 mouse myeloma line with spleen cells from $\text{BALB}\text{c}$ mice immunized against ovalbumin produced hybrid cells which continuously secrete antibodies specific for ovalbumin. One of these cells was used to establish a cloned line. Studies of its antibody obtained either from ascites fluid or from medium from hybridoma cultures showed high titer and specificity against ovalbumin using the double antibody technique with rabbit anti-mouse immunobeads; the antibody proved to be of the IgG₁ (kappa) subclass and type.     

Monoclonal antibodies against human DNA polymerase-alpha inhibit DNA replication in permeabilized human cells

Monoclonal neutralizing antibodies against DNA polymerase-alpha substantially inhibit nuclear DNA replication in lysolecithin-permeabilized cultured human fibroblasts. The degree of inhibition of DNA synthesis is proportional to antibody concentration, and the effect is specific in that RNA synthesis measured under the same experimental conditions is unperturbed. Autoradiographic data demonstrate that the magnitude of the inhibition measured in the mass culture reflects the uniform response of all the constituent cells in the target population. These observations confirm the participation of DNA polymerase-alpha in replicative DNA synthesis and identify a versatile, novel approach to the dissection of mammalian processes of DNA replication and repair.     

Monoclonal antibodies that inhibit activation and proliferation of lymphocytes. II. Requisite role of the monoclonal antibody-defined antigen systems in activation and proliferation of human and rat lymphocytes

A murine monoclonal antibody (MoAb) B3 to rat cells and MoAb HBJ127 and HBJ98 to human cells were found previously to recognize the homologous antigen systems (gp130 in the rat and gp125 in the human) which are predominantly distributed on the cell surface of proliferating cells of the respective species, and the expression of the antigen systems in lymphocytes were indicated previously to correlate closely with the activation and proliferation of the lymphocytes. In this respect, the in vitro effects of these MoAb on the nucleic acid synthesis, cell cycles, or proliferation of stimulated rat and human lymphocytes were examined by use of T cell-enriched and B cell-enriched cell populations. The addition of B3 MoAb to cultures diminished Con A-induced or allogeneic mixed lymphocyte culture-induced rat T cell proliferation and lipopolysaccharide-induced rat B cell proliferation, whereas B31 MoAb, which is unreactive with the gp130 antigen, did not inhibit these lymphocyte responses. Similarly, both HBJ127 and HBJ98 MoAb could inhibit the human lymphocyte proliferation in vitro, although HBJ127 MoAb showed about eight times greater inhibitory activity than did HBJ98 MoAb; HBJ127 MoAb almost completely inhibited the DNA synthesis of the Con A-stimulated lymphocytes at concentrations higher than 13 micrograms/ml. The flow cytometric analysis of the cellular nucleic acid contents with acridine orange-stained cells showed that when B3 MoAb and Con A were simultaneously added to unstimulated rat T cells, progression of the cell cycle was blocked at the G0 to G1 transition. In this culture condition, the appearance of the B3-defined antigen was arrested in a moderate level, as determined with fluorescein-stained cells. On the addition of B3 MoAb to the culture of the T cells after 24-hr Con A stimulation, the MoAb also strongly inhibited the cellular DNA synthesis, but it did not arrest the cell cycle at a certain phase and did not modulate the corresponding antigen. These data suggest that the B3 MoAb-defined antigen on the rat lymphocytes and the HBJ127/HBJ98 MoAb-defined antigen on the human lymphocytes may play some requisite roles not only in lymphocyte activation but also in the subsequent progression through the cell cycle to proliferate.     

Selective macrophage activation by muramyldipeptide bound to monoclonal antibodies specific for mouse tumor cells

Summary IgM monoclonal antibodies directed against tumor cells which do not mediate antibody-dependent macrophage cytotoxicity (ADMC) even when they are cytotoxic in the presence of complement, have been shown to render macrophages tumoricidal when they carry an immunomodulating agent, i.e., muramyldipeptide (MDP).This statement is based on experiments using two IgM monoclonal antibodies selected for their ability to bind L1210 leukemia cells (F₂-10-23-IgM) and 3LL Lewis lung carcinoma cells (6B6-IgM) specifically, as shown by flow cytofluorometry analysis.The MDP-IgM conjugates, containing 45 MDP molecules per IgM molecule, were prepared by allowing MDP-hydroxy-succinimide ester to react with IgM monoclonal antibodies.The MDP-IgM conjugates are shown to bind to relevant tumor cells and to induce the activation of thioglycolate-elicited peritoneal mouse macrophages leading to 80% growth inhibition of target cells at optimum concentrations of bound MDP. These concentrations of bound MDP were 10 times lower than the concentration of free MDP, giving a maximum activation that is limited to 20% growth inhibition.No macrophage activation was evidenced when tumor cells were incubated in the presence of irrelevant MDP-IgM conjugates and macrophages or when macrophages were preincubated in the presence of MDP-IgM conjugates and then incubated in the presence of relevant or irrelevant tumor cells but in the absence of the MDP-IgM conjugates.The reported results are discussed with reference to the mechanism of activation of macrophage by muramyldipeptide and to the usefulness of such MDP-IgM conjugates as potential antitumor agents in cancer therapy.Abbreviations ADMC antibody dependent macrophage mediated cytotoxicity - F-GAM fluoresceinylthiocarbamyl goat anti mouse antibody - -Man-BSA -mannopyranosyl-phenylthiocarbamyl bovine serum albumin containing some 25 mannose residues (neoglycoprotein) - MDP muramyldipeptide, 2-acetamido-3(2-0-d-lactyl-l-alanyl-d-glutamyl amine) glucopyranose - MDP-F₂-10-23-IgM Murine monoclonal antibody specific of L1210 leukemia cells and substituted with 45 MDP molecules - MDP—6B6-IgM Murine monoclonal antibody specific of 3LL Lewis lung carcinoma cells and substituted with 45 MDP molecules - MEM minimal essential medium - TDM Trehalose-dimycolate