Monoclonal antibodies that detect live salmonellae.

Nine immunoglobulin G and nine immunoglobulin M murine monoclonal antibody-producing hybridomas reactive with live Salmonella bacteria were obtained from several fusions of immune spleen cells and Sp2/0 myeloma cells. The antibodies were selected by the magnetic immunoluminescence assay. The monoclonal antibodies were reactive with serogroups A, B, C1, C2, D, E, and K and Salmonella choleraesuis subsp. diarizonae. Each monoclonal antibody proved to be reactive with a distinct serotype. Clinical isolates belonging to these Salmonella serogroups could be detected. Reactivity with non-Salmonella bacteria proved to be minor.     

Monoclonal antibodies that detect live salmonellae.

Nine immunoglobulin G and nine immunoglobulin M murine monoclonal antibody-producing hybridomas reactive with live Salmonella bacteria were obtained from several fusions of immune spleen cells and Sp2/0 myeloma cells. The antibodies were selected by the magnetic immunoluminescence assay. The monoclonal antibodies were reactive with serogroups A, B, C1, C2, D, E, and K and Salmonella choleraesuis subsp. diarizonae. Each monoclonal antibody proved to be reactive with a distinct serotype. Clinical isolates belonging to these Salmonella serogroups could be detected. Reactivity with non-Salmonella bacteria proved to be minor.     

Monoclonal antibodies specific for African swine fever virus proteins.

We have obtained 60 stable hybridomas which produced immunoglobulins that recognized 12 proteins from African swine fever virus particles and African swine fever virus-infected cells. Most of the monoclonal antibodies were specific for the three major structural proteins p150, p72, and p12. The specificity of some monoclonal antibodies for the structural proteins p150 and p37 and the nonstructural proteins p220 and p60 indicated that proteins p150 and p220 are antigenically related to proteins p37 and p60. The association of some viral antigens to specific subcellular components was determined by immunofluorescence and analysis of the binding of monoclonal antibodies to infected cells. A host protein (p24) seemed to be associated with the virus particles.     

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.     

An antiviral compound that blocks structural transitions of poliovirus prevents receptor binding at low temperatures

Drugs such as WIN51711 that inhibit picornavirus replication are thought to block poliovirus infectivity by binding to the capsid and preventing structural transitions required for uncoating. We examined the activity of WIN51711 at temperatures where capsid flexibility is thought to be decreased. Below 37 degrees C, WIN51711 inhibits the binding of wild-type poliovirus to cells but does not affect the binding of a poliovirus mutant which is believed to undergo structural transitions more readily. These results suggest that the poliovirus capsid must undergo structural changes to bind to its cellular receptor.     

Monoclonal antibodies that inhibit attachment of group B coxsackieviruses.

Hybridoma cell lines that secrete monoclonal antibodies which react with HeLa cell surface antigens were produced. The monoclonal antibodies prevented cytopathic effects caused by coxsackievirus B1 and significantly reduced the amounts of coxsackieviruses B1, B5, and B6 that absorb to HeLa cells. These antibodies did not protect the cells from poliovirus cytopathic effects, and they had no effect on the attachment of other picornaviruses to HeLa cells.     

Monoclonal antibodies that immunoreact with a cation-stimulated plant membrane ATPase.

Hybridoma technology has been used successfully to generate monoclonal-antibody probes against protoplast membrane antigens. Hybridomas secreting monoclonal antibodies that either inhibit or stimulate a putative plasma-membrane marker enzyme, (K+ + Mg2+)-stimulated pH 6.5 ATPase, have been identified and cloned. The specificity of monoclonal-antibody probes on the activity of other phosphate-hydrolysing enzymes has also been examined. The production and identification of monospecific antibodies capable of immunoreacting with particular component proteins in a complex plant membrane mixture highlight the usefulness of hybridoma methodology for the enzymologist, especially since such monoclonal antibodies can be used in the purification of proteins by immunoaffinity techniques.     

Monoclonal antibodies that target pathological assemblies of Abeta

Amyloid beta (Abeta) immunotherapy for Alzheimer's disease has shown initial success in mouse models of Alzheimer's disease and in human patients. However, because of meningoencephalitis in clinical trials of active vaccination, approaches using therapeutic antibodies may be preferred. As a novel antigen to generate monoclonal antibodies, the current study has used Abeta oligomers (amyloid beta-derived diffusible ligands, ADDLs), pathological assemblies known to accumulate in Alzheimer's disease brain. Clones were selected for the ability to discriminate Alzheimer's disease from control brains in extracts and tissue sections. These antibodies recognized Abeta oligomers and fibrils but not the physiologically prevalent Abeta monomer. Discrimination derived from an epitope found in assemblies of Abeta1-28 and ADDLs but not in other sequences, including Abeta1-40. Immunoneutralization experiments showed that toxicity and attachment of ADDLs to synapses in culture could be prevented. ADDL-induced reactive oxygen species (ROS) generation was also inhibited, establishing this response to be oligomer-dependent. Inhibition occurred whether ADDLs were prepared in vitro or obtained from Alzheimer's disease brain. As conformationally sensitive monoclonal antibodies that selectively immunoneutralize binding and function of pathological Abeta assemblies, these antibodies provide tools by which pathological Abeta assemblies from Alzheimer's disease brain might be isolated and evaluated, as well as offering a valuable prototype for new antibodies useful for Alzheimer's disease therapeutics.     

Monoclonal antibodies that react with Leishmania (Viannia) naiffi

Monoclonal antibodies were raised against Leishmania (Viannia) naiffi, which recently has been characterized as a new species. BALB/c mice were immunized with membrane-enriched fractions of a mixture of L. (V.) naiffi isolates. Subsequent fusion of immunized splenocytes with NS-1 myeloma cells resulted in the production of 5 Mabs (N1-N5). Screening by ELISA and indirect immunofluorescence against an extensive cross-panel of Leishmania strains revealed that N3 was species-specific and could thus be used to identify L. (V.) naiffi. N2 and N5 reacted only with strains of L. (V.) naiffi and Leishmania (Viannia) braziliensis, and therefore could be used in conjunction with N3 to identify L. (V.) braziliensis parasites. These species-specific Mabs will therefore be useful additions to the panel of antibodies already available for the identification of Leishmania species. N1 and N4 were found to recognize a small, glycosylated molecule present on all L. (V.) naiffi and L. (V.) braziliensis isolates that is related to the GIPL family of membrane glycophospholipids previously described for Leishmania (Leishmania) major.     

Monoclonal antibodies that bind the renal Na+/glucose symport system. 1. Identification

Phlorizin is a specific, high-affinity ligand that binds the active site of the Na+/glucose symporter by a Na+-dependent mechanism but is not itself transported across the membrane. We have isolated a panel of monoclonal antibodies that influence high-affinity, Na+-dependent phlorizin binding to pig renal brush border membranes. Antibodies were derived after immunization of mice either with highly purified renal brush border membranes or with apical membranes purified from LLC-PK1, a cell line of pig renal proximal tubule origin. Antibody 11A3D6, an IgG2b, reproducibly stimulated Na+-dependent phlorizin binding whereas antibody 18H10B12, an IgM, strongly inhibited specific binding. These effects were maximal after 30-min incubation and exhibited saturation at increased antibody concentrations. Antibodies did not affect Na+-dependent sugar uptake in vesicles but significantly prevented transport inhibition by bound phlorizin. Antibodies recognized a 75-kDa antigen identified by Western blot analysis of brush border membranes, and a 75-kDa membrane protein could be immunoprecipitated by 18H10B12. These properties, taken together with results in the following paper [Wu, J.-S.R., & Lever, J.E. (1987) Biochemistry (following paper in this issue)], provide compelling evidence that the 75-kDa antigen recognized by these antibodies is a component of the renal Na+/glucose symporter.     

Monoclonal antibodies that distinguish between two related digitalis glycosides, ouabain and digoxin.

The exogenous digitalis glycosides, ouabain and digoxin, have been widely used in humans to treat congestive heart failure and cardiac arrhythmias. Several reports have also pointed to the existence of endogenous ouabain- and digoxin-like compounds, but their precise roles in mammalian physiology and various disorders of the circulation are not clear. In an attempt to produce specific Abs for the purification and identification of endogenous ouabain-like compounds, somatic cell fusion was used to produce mAbs specific for ouabain. Our attempts to produce ouabain-specific mAbs were unsuccessful when ouabain was coupled to exogenous proteins such as bovine gamma-globulins, BSA, and human serum albumin. However, when ouabain was coupled to an Ab of A/J mice origin and the same strain of mouse was used for immunization with ouabain-Ab conjugate, three Abs (1-10, 5A12, and 7-1) specific for ouabain were obtained. In assays of fluorescence quenching and saturation equilibrium with tritiated ouabain, Ab 1-10 exhibited 200 nM affinity for ouabain. These three mAbs are distinguished from existing Abs to ouabain and digoxin by their specificity for ouabain and lack of cross-reactivity with digoxin. Specificity studies showed that the loss of cross-reactivity was correlated with the presence of a hydroxyl group at either position 12beta (digoxin) or 16beta (gitoxin) of the steroid ring. These Abs can be used to develop assays for detection and characterization of ouabain-like molecules in vivo.     

Monoclonal antibodies that distinguish between subspecies of human interferon-alpha and that detect interferon oligomers

Monoclonal antibodies to human interferons (HuIFN) of the alpha-class have been prepared by screening against 125I-labeled IFN in a rapid liquid-phase radioimmunoassay. All of the six antibodies produced react with HuIFN-alpha 2 and with some components of HuIFN-alpha N (Namalwa); three of the antibodies also bind HuIFN-alpha 1, and these either do not bind or bind very weakly the 25K component of Namalwa. Reaction of the antibodies with IFN components blotted onto nitrocellulose after separation on reducing gels suggests that two of the antibodies are against conformational determinants, whereas the epitopes recognized by the other antibodies are not destroyed by reduction or SDS treatment; these antibodies can be used to detect the presence of oligomers in IFN preparations. From the reaction of the antibodies with different alpha-IFN in immunoblots, in an antiviral assay, and in an ELISA, it was concluded that at least five different epitopes are recognized by the six antibodies, only one of which is non-neutralizing.     

Monoclonal antibodies that bind to galactosylgloboside (SSEA-3 antigen)

The 3-fucosyllactosamine (3-FL) antigenic determinant, Gal(beta 1-4)[Fuc(alpha 1-3)]-GlcNAc-R, is very immunogenic in BALB/c mice. A panel of monoclonal antibodies was raised against a novel glycosphingolipid that contains a terminal 3-FL structure (structure 1): (formula: see text) Surprisingly, most of these antibodies reacted with the internal galactosylgloboside structure rather than with the terminal 3-FL epitope. The specificities of two of these antibodies, 5A3 and 8A7, were analyzed by enzyme-linked immunosorbent assay and immunostaining procedures, and compared with MC631 (anti-SSEA-3), the only other monoclonal antibody known to bind to galactosylgloboside. 5A3 and 8A7 bound equally well to structure 1 and to galactosylgloboside. These antibodies also bound to structure 1 from which the terminal galactose, or the galactose and fucose, had been removed, but not to globoside or sialylated galactosylgloboside. In contrast, MC631 did not bind to structure 1 but, as described previously, did bind to globoside and sialylated galactosylgloboside. Galactosylgloboside is a developmentally regulated antigen of mouse embryos, human teratocarcinomas, and mouse embryonic brain. Antibodies 5A3 and 8A7 will complement MC631 in the analysis of the distribution and regulation of galactosylgloboside.     

Monoclonal antibodies that distinguish non-small cell from small cell lung cancer

Two murine IgG2Ak monoclonal antibodies (703D4, 704A 1) were produced and characterized after immunization with a human large cell lung cancer line (NCI-H 157). These antibodies detect different epitopes on 31 kilodalton [35S]methionine incorporating protein(s). Radiobinding and immunohistochemical studies show these antibodies bind to most (11/13) human non-small cell lung cancer (adenocarcinoma, epidermoid, and large cell), but not to small cell lung cancer (0/11) tumors tested. The epitopes these antibodies recognized are also expressed on human melanomas (7/8), two other tumors (osteogenic sarcoma, renal cell carcinoma), but not on many other human tumors (breast, colon, neuroblastoma, lymphoid), and not on a panel of normal adult human tissues. Because the antigen(s) are preserved after fixation and because of their ability to distinguish lung cancer types from each other and normal tissues, they should be of clinical, as well as of biologic interest.     

Monoclonal antibodies distinguish synthetic peptides that differ in one chemical group

By using human calcitonin (hCT), human calcitonin-gene-related peptide (hCGRP), and a synthetic peptide with a sequence analogous to the 34 C-terminal amino acids of human preprocalcitonin (designated as PQN-34) as haptens in the generation of monoclonal antibodies, we assessed the role of amido and amino groups in paratope-epitope binding. By using peptide inhibition experiments and solid-phase immunoassays, monoclonal anti-hCT antibody CT07 and monoclonal anti-hCGRP antibody CGR01 were found to bind to an antigenic determinant located in the C-terminal segment of the hormones. These epitopes comprise the seven C-terminal amino acids of the hormones, and the presence of the hormone-ending carboxamide group was found to be essential for antibody binding. The corresponding heptapeptides, either bearing a carboxyl group or else linked to a glycine residue at their C-terminal part, failed to react with the antibodies. Moreover, these monoclonal antibodies did not bind to synthetic peptides analogous to the C-terminal region of the hormone precursor molecules that comprised the epitope site flanked by a peptide sequence. In an attempt to assess whether amido groups when present on the side-chain of amino acids may also modulate antibody binding, a monoclonal antibody referred to as QPO1 was produced and was found to recognize an antigenic determinant localized in the N-terminal region of the PQN-34 peptide bearing a glutamine residue as the N-terminal amino acid. The epitope was found to correspond to a topographic assembled site, and binding of QPO1 was found to be substantially dependent on the presence of the free amino and the side-chain amido groups borne by the N-terminal glutamine residue of this peptide PQN-34. In contrast to these findings, an antigenic determinant located in the internal sequence of calcitonin and recognized by monoclonal anti-hCT antibody CT08 was found to be expressed on the mature form of the hormone, as well as on synthetic peptides with sequence mimicking that of preprocalcitonin. These data should guide the choice of synthetic peptide haptens for the production of anti-protein antibodies.     

Endotoxin and prostaglandin fever of newborn guinea pigs at different ambient temperatures.

At an ambient temperature (Ta) of 30 degrees C, injection of 0.2 micrograms E. coli endotoxin into the lateral cerebral ventricle (icv) of three-day-old or younger guinea pigs was followed by a biphasic febrile rise in body temperature (Tc) and oxygen consumption (VO2), interrupted by a transient fall. At Ta 20 degrees C the change in Tc and VO2 was still biphasic, the first rise was similar as that seen at Ta 30 degrees C, but the subsequent fall was more pronounced. Thus, Tc became lower than before endotoxin and remained below the pre-injection level during and after the second rise. Injection of 10 ng PGE1 icv caused sustained monophasic hyperthermia at both Ta-s. Icv injection of 0.9% NaCl did not affect Tc and VO2 at either Ta. Accordingly, prostaglandins might contribute to, but cannot account for, the whole febrile response to endotoxin.     

Monoclonal antibodies that inhibit the enzyme activity of NAD(+)-dependent 15-hydroxyprostaglandin dehydrogenase.

Three hybridoma cell lines secreting antibodies against human placental NAD(+)-dependent 15-hydroxyprostaglandin dehydrogenase (15-OH-PGDH) were produced. Purified IgG2b from these cell lines recognized a distinct band of Mr 28,000 on SDS/PAGE from the purified enzyme as well as a band of Mr 56,000 from the crude enzyme preparation. These three monoclonal antibodies inhibited 15-OH-PGDH activity to different degrees. Inhibition of the enzyme activity could be prevented by prior incubation of the enzyme with NAD+ but not with prostaglandin E2 (PGE2) or NADP+. Inhibition by monoclonal antibodies appears to be non-competitive with respect to NAD+ and PGE2. An increased concentration of antibodies alters the apparent Km for NAD+ but not for PGE2, further supporting the notion that the antibodies bind to the coenzyme-binding site. The availability of these monoclonal antibodies should be valuable for probing the structure of the active site.