Production of monoclonal antibodies against calmodulin by in vitro immunization of spleen cells

A novel arctigenin-containing latex glove prevents latex allergy by inhibiting type I/IV allergic reactions

The present study aimed at developing a natural compound with anti-allergic effect and stability under latex glove manufacturing conditions and investigating whether its anti-allergic effect is maintained after its addition into the latex. The effects of nine natural compounds on growth of the RBL-2H3 cells and mouse primary spleen lymphocytes were determined using MTT assay. The compounds included glycyrrhizin, osthole, tetrandrine, tea polyphenol, catechin, arctigenin, oleanolic acid, baicalin and oxymatrine. An ELISA assay was used for the in vitro anti-type I/IV allergy screening; in this process β-hexosaminidase, histamine, and IL-4 released from RBL-2H3 cell lines and IFN-γ and IL-2 released from mouse primary spleen lymphocytes were taken as screening indices. The physical stability of eight natural compounds and the dissolubility of arctigenin, selected based on the in vitro pharnacodynamaic screening and the stability evaluation, were detected by HPLC. The in vivo pharmacodynamic confirmation of arctigenin and final latex product was evaluated with a passive cutaneous anaphylaxis (PCA) model and an allergen-specific skin response model. Nine natural compounds showed minor growth inhibition on RBL-2H3 cells and mouse primary spleen lymphocytes. Baicalin and arctigenin had the best anti-type I and IV allergic effects among the natural compounds based on the in vitro pharmacodynamic screening. Arctigenin and catechin had the best physical stability under different manufacturing conditions. Arctigenin was the selected for further evaluation and proven to have anti-type I and IV allergic effects in vivo in a dose-dependent manner. The final product of the arctigenin-containing latex glove had anti-type I and IV allergic effects in vivo which were mainly attributed to arctigenin as proved from the dissolubility results. Arctigenin showed anti-type I and IV allergic effects in vitro and in vivo, with a good stability under latex glove manufacturing conditions, and a persistent anti-allergic effect after being added into the latex to prevent latex allergy.

Redefining an epitope of a malaria vaccine candidate, with antibodies against the N-terminal MSA-2 antigen of Plasmodium harboring non-natural peptide bonds

The aim of obtaining novel vaccine candidates against malaria and other transmissible diseases can be partly based on selecting non-polymorphic peptides from relevant antigens of pathogens, which have to be then precisely modified for inducing a protective immunity against the disease. Bearing in mind the high degree of the MSA-2^21–40 peptide primary structure’s genetic conservation among malaria species, and its crucial role in the high RBC binding ability of Plasmodium falciparum (the main agent causing malaria), structurally defined probes based on non-natural peptide-bond isosteres were thus designed. Thus, two peptide mimetics were obtained (so-called reduced amide pseudopeptides), in which naturally made amide bonds of the ³⁰FIN³²-binding motif of MSA-2 were replaced with ψ–[CH₂–NH] methylene amide isostere bonds, one between the F–I and the second between I–N amino acid pairs, respectively, coded as ψ-128 ψ-130. These peptide mimetics were used to produce poly- and monoclonal antibodies in Aotus monkeys and BALB/c mice. Parent reactive mice-derived IgM isotype cell clones were induced to Ig isotype switching to IgG sub-classes by controlled in vitro immunization experiments. These mature isotype immunoglobulins revealed a novel epitope in the MSA-2^25–32 antigen and two polypeptides of rodent malaria species. Also, these antibodies’ functional activity against malaria was tested by in vitro assays, demonstrating high efficacy in controlling infection and evidencing neutralizing capacity for the rodent in vivo malaria infection. The neutralizing effect of antibodies induced by site-directed designed peptide mimetics on Plasmodium’s biological development make these pseudopeptides a valuable tool for future development of immunoprophylactic strategies for controlling malarial infection.

Visualization of the Ca-transport system of the mitotic apparatus of sea urchin eggs with a monoclonal antibody

Monoclonal antibodies have been obtained to components of Ca(2+)-sequestering vesicles from the endoplasmic reticulum of HeLa cells by isolating hybridomas that were generated by the in vitro immunization of lymphocytes followed by fusion with plasmocytoma cells. One of these monoclonal antibodies specifically labels punctate structures which appear in the mitotic apparatus of sea urchin eggs at the beginning of prophase and disappear upon the completion of cytokinesis. The antibody inhibits the Ca(2+) uptake of the membrane system in vitro. It reacts with one 46-kDa protein out of the complex protein mixture from the membrane fraction. We take all this as evidence that in fact a specific Ca(2+)-transport system is part of the mitotic apparatus, that such a system is very conserved, and that it is most probably derived from the endoplasmic reticulum.

Expression of masticatory-specific isoforms of myosin heavy-chain, myosin-binding protein-C and tropomyosin in muscle fibers and satellite cell cultures of cat masticatory muscle

We test the hypothesis that cat jaw satellite cells belong to a distinct lineage preprogrammed to express masticatory-specific isoforms of myosin heavy-chain (m-MyHC), myosin-binding protein-C (m-MBP-C), and tropomyosin (m-Tm) during myogenesis in vitro. A monoclonal antibody (MAb) against m-MyHC and MAbs raised here against cat m-MBP-C and m-Tm were used to stain cryostat sections of cat masseter muscle and cultured myotubes derived from satellite cells of cat temporalis and limb muscles, using peroxidase immunohistochemistry. MAbs against m-MBP-C bound purified m-MBP-C in Western blots. MAbs against m-Tm failed to react with m-Tm in Western blots, but reacted with native m-Tm in gel electrophoresis-derived ELISA. In cat masseter sections, MAbs against m-MyHC, m-MBP-C, and m-Tm stained all masticatory fibers, but not the jaw-slow fibers. Cat jaw and limb muscle cultures mature significantly more slowly relative to rodent cultures. However, at 3 weeks, all three MAbs extensively stained temporalis myotubes, whereas they apparently stained isolated myotubes weakly in cat limb and rat jaw cultures. We conclude that satellite cells of masticatory fibers are preprogrammed to express these isoforms during myogenesis in vitro. These results consolidate the notion that masticatory and limb muscle allotypes are distinct.

Antibodies induced by Plasmodium falciparum merozoite surface antigen-2-designed pseudopeptides possess neutralizing properties of the in vitro malarial infection

Pseudopeptide chemistry is gaining ground in the field of synthetic vaccine development. We have previously demonstrated the potential scope of introducing reduced amide peptide bond isosters in a site-directed design for obtaining structurally modified probes able to induce malaria infection-neutralizing antibodies derived from the MSP-1 antigen. This work reports the functional properties of polyclonal and monoclonal antibodies induced by site-directed designed MSP-2 N-terminus pseudopeptides and their capacity for antibody isotype switching in in vitro immunization. Structural properties of the native peptide and its pseudopeptide analogs are discussed within the context of these novel pseudopeptides' induced monoclonal antibody functional and physical-chemical properties.

Directed evolution for the development of conformation-specific affinity reagents using yeast display

Yeast display is a powerful tool for increasing the affinity and thermal stability of scFv antibodies through directed evolution. Mammalian calmodulin (CaM) is a highly conserved signaling protein that undergoes structural changes upon Ca(2+) binding. In an attempt to generate conformation-specific antibodies for proteomic applications, a selection against CaM was undertaken. Flow cytometry-based screening strategies to isolate easily scFv recognizing CaM in either the Ca(2+)-bound (Ca(2+)-CaM) or Ca(2+)-free (apo-CaM) states are presented. Both full-length scFv and single-domain VH only clones were isolated. One scFv clone having very high affinity (K(d) = 0.8 nM) and specificity (>1000-fold) for Ca(2+)-CaM was obtained from de novo selections. Subsequent directed evolution allowed the development of antibodies with higher affinity (K(d) = 1 nM) and specificity (>300-fold) for apo-CaM from a parental single-domain clone with both a modest affinity and specificity for that particular isoform. CaM-binding activity was unexpectedly lost upon conversion of both conformation-specific clones into soluble fragments. However, these results demonstrate that conformation-specific antibodies can be quickly and easily isolated by directed evolution using the yeast display platform.

Antibody specific for phosphorylated AMPA-type glutamate receptors at GluR2 Ser-696

Possible phosphorylation sites on the Purkinje cell alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA)-type glutamate receptor subunits were identified using in vitro kinase assays of 17 synthetic peptides derived from the transmembrane-3 (TM3) domain to the end of C-terminal of a rat glutamate receptor 2 (GluR2). Only two peptides containing Ser-662 and Ser-696 were found to be efficiently phosphorylated by protein kinase C (PKC). The peptide including Ser-696 was also phosphorylated by protein kinase G (PKG). Another peptide containing Thr-692 of a rat GluRA, clone almost identical to GluR1, was phosphorylated by PKC but not by PKG. Antisera recognizing phosphorylated AMPA receptor subunits at GluR2 Ser-696 or the homologous sites of GluR1/3/4 were produced, and the specificity of one of them, named 12P3, was established by enzyme-linked immunosorbent assay (ELISA), immunoblot and immunoprecipitation analyses. 12P3-immunocytochemistry on cerebellar slices demonstrated an AMPA-induced transient AMPA receptor phosphorylation, which appeared in Purkinje cell dendrites as well as somata immediately after AMPA treatment and disappeared after 20 min. This antibody may be a useful tool to study the role of AMPA receptor phosphorylation in producing synaptic plasticity.

Production and characterization of separate monoclonal antibodies to human brain and erythrocyte acetylcholinesterases

Four murine monoclonal antibodies (MAbs) of the IgM class were raised against human acetylcholinesterase (AChE; Ec 3.1.1.7). The MAbs BMS-3E4, BMS-7G10, and BMS-9F4 all recognized human erythrocyte AChE, while BMS-6D6 bound specifically to human soluble brain AChE, on the basis of immunobinding assays. Dose-response studies gave an ELISA ED50 titer of 4.5 x 10(-4) M for BMS-6D6, while BMS-3E4 gave the best titer at 8.8 x 10(-4) M. Sucrose density gradients demonstrated sedimentation of antigen-antibody complexes, consistent with earlier findings (i.e., BMS-6D6 bound with brain AChE while BMS-3E4 preferred erythrocyte (AChE). No cross-reactivity between the two MAbs against the two antigens was noted.

Functional conformations of calmodulin: I. Preparation and characterization of a conformational specific anti-bovine calmodulin monoclonal antibody

Calmodulin, similarly to many other Ca(2+)-activated proteins, undergoes considerable conformational changes in the presence of Ca2+ ions. These changes were followed using specific monoclonal antibodies against calmodulin. Since calmodulin is a poor immunogen due to its high phylogenetic conservancy, glutaraldehyde-crosslinked bovine brain extract, which contains a considerable amount of functionally active calmodulin complexed with its target proteins, was used as an antigen. Out of nine anti-calmodulin mAbs isolated, three (namely, CAM1, CAM2 and CAM4) were purified and characterized. MAb CAM1 was identified as an IgG1 while mAbs CAM2 and CAM4 belong to IgM class. Additivity ELISA showed that mAb CAM1 binds to an epitope located remote from the epitopes recognized by the other two mAbs, while mAbs CAM2 and CAM4 recognize close epitopes. MAb CAM1 was found to be especially sensitive to the conformational state of calmodulin in the presence of Ca2+ ions. The interactions of mAbs CAM2 and CAM4 with calmodulin are only slightly affected by Ca2+ removal. In addition mAb CAM1 failed to recognize other calmodulin molecules, such as spinach and various plant recombinant calmodulins, while mAbs CAM1 and CAM4 share common epitopes with the above molecules.

Production and characterisation of monoclonal antibodies against pyelonephritis-associated P-pili of Escherichia coli

Pyelonephritis-associated P-pili (PAP) of Escherichia coli O6,H(-),K1(-),F12,haemolysin(-) were purified by salt precipitation and affinity chromatography using Synsorb P1. Purified PAP showed a single band with a molecular weight of 18 kDa by electrophoretic analysis. A monoclonal antibody (mAb) was produced by fusion of the PAI myeloma cell line with splenic lymphocytes from BALB/c mice immunised with the purified PAP. The mAb was of IgM class with kappa light chains and reacted with a 18-kDa moeity of the salt precipitate; the epitope was present near the apical part of the pilus filaments. The mAb reacted with PAP in both immunofluorescence and haemagglutination tests when 108 strains isolated from urine samples were tested; the two tests were in agreement for 202 of 204 strains isolated from faecal samples.

Immunohistochemical detection of an enamel protein-related epitope in rat bone at an early stage of osteogenesis

Monoclonal antibody MI315 was produced against hamster tooth germ homogenate by in vitro immunization. It was found that MI315 reacted with enamel matrix, ameloblasts, and bone matrix at an early stage of osteogenesis. Decalcified tissues of rat femurs and mandibles were examined with MI315 using indirect immunofluorescence. In endochondral ossification of femurs, immunoreactivity was found in bone extracellular matrix (ECM) deposited on the surface of the cartilage core of primary spongiosa, but not in the cartilage core itself. In intramembranous ossification of 0-day-old rat mandibles, intense immunofluorescence was detected in bone ECM and a few young osteocytes, but not in osteoblasts. Immunoreactivity in bone ECM of 2-day-old rats decreased and almost disappeared from bone ECM of 4-day-old rats. Although in nondecalcified sections of 0-day-old rats, negligible immunofluorescence was detected in bone ECM which showed positive staining in decalcified tissues, the immunostaining appeared after decalcification using ethylenediaminetetraacetic acid (EDTA). These results indicate that a substance(s), which had a common epitope with an enamel-derived protein(s), existed in immature bone ECM of both endochondral and intramembranous ossification, and that it might be masked by bone mineral. Monoclonal antibody MI315 is a useful tool to investigate the time- and position-specific changes in osteogenesis and amelogenesis.

A simple in vitro method for raising monoclonal antibodies to cochlear proteins

Monoclonal antibodies have been produced to mammalian hair cell antigens using a simple in vitro kit. Antigen was crudely prepared from dissected cochlear tissue by detergent extraction. There was no need to purify hair cells. Hybridoma supernatents were screened most efficiently on dissociated cells fixed with acetone. The immunisation method is sensitive to nanograms of antigen and can generate responses to conserved or weak antigens. The kit requires very little previous experience with cell culture and generates monoclonal antibodies within 3-4 weeks. It has overcome a number of problems with production of antibodies to hair cells and it should prove to be a very valuable tool in many laboratories.

Production of monoclonal antibodies specific for African swine fever virus following in vitro primary immunization of mouse splenocytes in the presence of stimulated T lymphocyte supernatants

Splenocytes from non-immune mice were stimulated in vitro using a kit of cytokine preparations (obtained from murine MLR and EL-4 cell cultures), and concomitantly immunized with African swine fever (ASF) virus antigen. In addition, fusions were performed at 5 days after primary or secondary stimulation/immunization. The detection of specific antibodies in the culture supernatants was not successful. In contrast, specific antibody-producing hybridomas could be generated, and this was at least comparable to a standard in vivo immunization regime, even though the optimum fusion ratio employed with these in vitro immunized splenocytes was one which is not optimum when in vivo immunized lymphocytes are used. Consequently, it would appear that hybridoma generation is a more sensitive method than the direct measurement of antibody at detecting in vitro primary immune responses. After primary in vitro immunization, the majority of immunoglobulins produced were apparently of the IgG isotype, with only 8-17% clearly IgM. These antibodies were mainly against VP73 (the major viral envelope protein) as expressed on viral antigen extracted from infected cells, although other specificities were also found. This demonstrated, by in vitro means, that the VP73 carried dominant immunogenic epitopes on ASF virus. Such observations show that the in vitro responses were closely related to those which have been detected in vivo.

Monoclonal antibody to calmodulin: development, characterization, and comparison with polyclonal anti-calmodulin antibodies

Specific anti-calmodulin rabbit polyclonal and murine monoclonal antibodies have been produced with a thyroglobulin-linked peptide corresponding to amino acids 128-148 of bovine brain calmodulin. The monoclonal antibody is IgG-1 with kappa light chains. Both sets of antibodies recognize native vertebrate calmodulin, with the polyclonal antibody exhibiting an approximately fourfold higher sensitivity than the monoclonal antibody in a radioimmunoassay. The affinity of both polyclonal and monoclonal antibodies is approximately 2.5-fold higher for Ca(2+)-free calmodulin than for Ca(2+)-calmodulin. Other selected members of the calmodulin family (S100, troponin, and parvalbumin) do not exhibit significant cross-reactivity with the monoclonal antibody. Troponin and S100 beta displace some 125I-calmodulin from the polyclonal antibody, but require at least 900-fold excess concentration. The monoclonal antibody recognizes intact vertebrate calmodulin in solution and also on solid-phase. In addition, plant calmodulin and some forms of post-translationally modified calmodulin (phosphorylated or glycated) bind the monoclonal antibody. The affinity of the monoclonal antibody is approximately 5 x 10(8) liters/mol determined by displacement of 125I-calmodulin. On dot blotting the sensitivity for vertebrate calmodulin is 50 pg. The epitope for the monoclonal antibody is in the carboxyl terminal region (residues 107-148) of calmodulin. This highly specific anti-calmodulin monoclonal antibody should be a useful reagent in elucidating the mechanism by which calmodulin regulates intracellular metabolism.

In vitro immunization of rat spleen lymphocytes with Forssman glycosphingolipid antigen and the generation of a monoclonal antibody

A procedure for in vitro immunization of splenic lymphocytes with a glycolipid antigen is described. Culture medium supernatant of ConA- and PHA-stimulated spleen cells and that of Con A-stimulated human Jurkat T cell line (IL-2-rich medium) were used as sources of cytokines to support T and B cell stimulation, and anti-mu was used to support B cell differentiation. Unprimed rat spleen cells (2 x 10(6)/ml) were stimulated with 2 micrograms/ml Forssman glycolipid antigen coupled to Sepharose for 4 days. The cells were fused with a mouse myeloma cell line P3-X63-Ag8-U1. At initial screening, 12% of the colony forming wells were secreting specific antibody. After cloning, a stable hybridoma cell line (designated 4C3) was established which secreted a monoclonal IgM antibody directed against the carbohydrate moiety of Forssman glycosphingolipid (GalNAc alpha 1-3GalNAc beta 1-3Gal alpha 1-4Gal beta 1-4Glc-ceramide).

Mosaic pattern of lactase expression by villous enterocytes in human adult-type hypolactasia

Immunohistological analysis of the expression of lactase protein in adults with hypolactasia has been carried out using monoclonal antibodies. Eight different antibodies that recognize at least three distinct epitopes on the lactase protein each gave the same result. Strong brush border staining was observed in all the lactase-persistent adults. No staining at all was detected in 9 of the hypolactasic subjects. In the remaining 12 individuals a mosaic pattern of expression was observed: small patches of enterocytes stained strongly, whereas the surrounding areas showed no staining at all. Sucrase-isomaltase, in contrast, showed no such mosaicism in these or in any of the other individuals. The mosaicism observed in the 12 hypolactasic individuals suggests that the differentiation of the columnar cells along the villus is not homogeneous. Furthermore, the existence of two patterns of expression of the lactase protein in the lactase-deficient individuals (i.e., absence of protein and mosaicism), if characteristic of the entire length of the intestine of the individuals tested, would suggest the existence of two phenotypes of adult-type hypolactasia in the population studied.

Species- and infective stage-specific monoclonal antibodies to Leishmania major produced by an in vitro immunization method

Monoclonal antibodies specific to the infective-stage promastigotes of Leishmania major are needed for developing rapid diagnostic assays of infected sand flies. An in vitro immunization protocol was applied for the production of monoclonal antibodies using small amounts of L. major. Infective-stage promastigotes were isolated from sand flies (Phlebotomus papatasi) 7-10 days after infection and used as antigen for immunization. Two weeks after a primary immunization, murine splenocytes were removed and immunized in vitro with antigen in murine EL-4 thymoma cell conditioned medium. Three fusions were performed using X63-Ag.653 myeloma cells as fusion partners and two fusions were performed using FOX-NY cells. Antibodies specific to promastigotes were detected using an indirect enzyme-linked immunosorbent assay (ELISA). Initially 56 monoclonal antibodies were selected, and their species and stage specificity were determined using both an ELISA and an indirect fluorescent antibody assay (IFA). Twelve monoclonal antibodies showed species specificity to L. major when tested against four sympatric species of Leishmania. Four other monoclonal antibodies showed species and infective-stage specificity to L. major promastigotes. When tested in immunoblots, all four species- and stage-specific monoclonal antibodies bound to five protein bands that were unique to the infective-stage promastigotes.

Structurally distinct mammalian calmodulins

Rabbits immunized with dinitrophenylated calmodulin produced monospecific antibody against CaM. Using the purified antibody, enzyme-linked immunosorbent assays (ELISAs) were carried out for calmodulin (CaM). The immunological heterogeneity of human and bovine CaMs from erythrocytes was investigated by means of indirect and inhibition ELISAs. The cross-reactivity between the two CaMs was found to be 50% in the indirect ELISA. An eight times higher concentration of human CaM was necessary to produce 30% inhibition in an inhibition assay. The effect of anti-bovine CaM on the stimulation of the red cell membrane calcium pump by human and bovine CaM has also been studied. We have found that (a) the human and bovine CaMs showed indistinguishable activator activities; (b) the antibody partially inhibited the stimulating effects of CaMs; (c) the inhibition was much less effective in the case of stimulation by human CaM. These results suggest that there is a difference in the reactivity of the anti-bovine CaM antibody with bovine and human CaMs. This difference can be attributed to a slight deviation in the antibody binding structure of the two mammalian CaMs in or near the antigenic site of the CaMs.

Production of monoclonal antibodies against avian LHRH-I

Production of antibodies against peptides or poorly antigenic proteins by conventional methods often requires either large quantities of the native immunogen or some chemical modification to increase their antigenicity. In this study an in vivo and in vitro immunization protocol has been used to generate monoclonal antibodies against the decapeptide luteinizing hormone-releasing hormone (LHRH). Two injections of 100 micrograms of avian LHRH-I into BALB/c mice were given 7 d apart. Dissociated splenocytes were collected under sterile conditions. They were incubated with 100 micrograms of the immunogen in 75-cm2 tissue culture flasks in thymocyte-conditioned media. After 5 to 8 d exposure to the antigen, splenocytes were fused with SP2/O myeloma cells by polyethylene glycol. The cells were plated into 24 wells and then incubated in hypoxanthine aminopterin and thymidine selective media. After 14 d an initial screening was done by enzyme immunoassay. The positive wells (6/24) were expanded into 96-well plates and rescreened. Selected lines were cloned out 3 times by limiting dilution and the most positive expanded for ascites production. The antibody was affinity purified in a protein A column. The antibody cross-reacted with LHRH-I and II but preferentially to LHRH-I, as shown by competitive assay. A hypothalamic extract from a mature chick showed a higher response than preparations from whole brain explants of 1- to 3-d posthatched chicks, mature quail, and mature mouse.

Optimal conditions for the generation of monoclonal antibodies using primary immunisation of mouse splenocytes in vitro under serum-free conditions

We have further optimised the serum-free in vitro immunisation system described by Ossendorp et al. (J. Immunol. Methods 91, 257, 1986) for the generation of hybridomas secreting specific antibodies. Thyroglobulin and the hapten 2-phenyl-5-oxazolone coupled to chicken serum albumin were used as antigens. For an optimal outgrowth of antigen-specific B cells the presence of T cells, thymocyte-conditioned medium and antigen are required. The addition of supernatant from EL-4 cells (stimulated by phorbolmyristate acetate) inhibits the outgrowth of antigen-specific B cells. Using six-well plates with a surface area of 10 cm2 per well, an optimal IgM response was obtained when 10(7) splenocytes in a total volume of 2 ml/well were cultured for 3 days in the presence of antigen and thymocyte-conditioned medium. Increasing the concentration of cells whilst maintaining a constant surface area resulted in a decreased response.

In vitro stimulation of immune spleen cells enhances the number of anti-lipid A-producing hybridomas

An in vitro stimulation method for the generation of hybridomas producing antibodies with specificity for the weakly immunogenic lipid A is described. Conditions influencing in vitro stimulation of immune spleen cells were investigated. Depending on the experimental conditions the percentage of specific antibody-producing hybridomas varied between 0 and 39%. Most successful was stimulation with both antigen and the synthetic adjuvant muramyl dipeptide (MDP) for 3 days. In vitro stimulation of spleen cells from animals classically immunized with Salmonella Re mutant enhanced the number of lipid A-specific IgG-producing hybridomas from six after direct fusion to 17 after stimulation. These experiments indicate that the synergistic action of antigen and MDP is caused by preferential action on antigen selected B cells.

Effective production of mouse monoclonal antibodies against influenza virus by repeated intrasplenic immunization

Two immunization techniques that enable production of mouse monoclonal antibodies were evaluated in terms of small quantities of antigen. Various amounts of purified influenza A virus particles were applied either for in vitro sensitization in cultured splenocytes or for intrasplenic immunization, followed by hybridization of the immunized cells with mouse myeloma cells. Hybridomas producing specific antibodies for influenza viral proteins were detected by enzyme-linked immunosorbent assay when more than 50 micrograms of antigens was used for the in vitro immunization method, and at least 5 micrograms was necessary for a single intrasplenic immunization. On the other hand, as little as 60 ng of antigen administered in two intrasplenic injections was sufficient to produce specific hybridomas. Two out of six randomly selected monoclonal antibodies obtained using the repeated intrasplenic immunization method were IgG and the other four were IgM. Immunoprecipitation analyses revealed that the recognized antigens involved a viral inner protein (nucleocapsid protein), as well as an envelope glycoprotein (hemagglutinin). We conclude that immunization by two direct injections of antigen into the spleen is the most effective method for sensitization with nanogram quantities of insoluble antigen such as influenza viruses.

Monoclonal antibodies to the molluscan small cardioactive peptide SCPB: immunolabeling of neurons in diverse invertebrates

We reported a development of murine monoclonal antibodies to a molluscan small cardioactive peptide (SCPB) and their application to immunolabeling of neurons in several molluscan and arthropod species. In vitro stimulations of mouse lymphocytes with SCPB conjugated to a carrier protein yielded exclusively IgM class antibodies; in vivo stimulation resulted in generation of both IgM and IgG classes of antibodies. Monoclonal antibodies of the IgM class labeled identified SCP-containing neuron B11 in the frozen sections of the buccal ganglia of Tritonia diomedia. These antibodies failed to stain any neurons in whole mount preparations. A monoclonal antibody of IgG1 subclass selectively labeled neurons in both frozen sections and whole mount preparations of diverse invertebrate species. Thus, neurons B11, B12, and GE1 and several other neurons of the buccal and gastroesophageal ganglia of T. diomedia bound the antibody, and a similar pattern of immunolabeling was found in the closely related gastropod Tritonia festiva. We also observed SCPB-like immunoreactivity in the central neurons of other nudibranch and pulmonate molluscs and in examples of insect (Acheta domesticus and Tehrmobia domestica) and crustacean (Semibalanus cariosus) classes of the Arthropoda. Our results suggest a specific pattern of distribution of SCPB-like immunoreactivity in the gastropod nervous system and a broad occurrence of SCPB-like antigenicity in the diverse invertebrates.

Production of a monoclonal antibody against the Snow Mountain agent of gastroenteritis by in vitro immunization of murine spleen cells

The Snow Mountain agent (SMA) is a 27- to 32-nm noncultivatable virus that causes acute gastroenteritis in humans. SMA is morphologically similar to but immunologically distinct from the Norwalk agent. SMA has been partially purified from the stool of experimentally infected volunteers and contains a single structural protein of Mr 62,000 as well as one or more non-virion-associated soluble proteins. Further characterization of this important human pathogen and other Norwalk-like viruses has been hindered by the lack of reagents with which to study them. To further characterize SMA, we developed a monoclonal antibody to SMA using in vitro immunization--a technique that permitted use of small quantities of antigen for immunization. The monoclonal antibody, SM-4, was specific for SMA and did not react with the Norwalk or Hawaii agents. In addition, SM-4 reacted with purified virion but not with the soluble protein. SM-4 also blocked the ability of labeled postinfection human IgG to bind to purified virion. Finally, both SM-4 and human postinfection sera specifically recognized the Mr 62,000 virion-associated protein. Thus, SM-4 is directed against an epitope present on the SMA structural protein that is not shared by the Norwalk or Hawaii agents and that is not present on the soluble protein. The availability of a monoclonal antibody against SMA should facilitate further purification and characterization of this agent. The techniques utilized in these studies provide a method for the production of additional monoclonal antibodies to this group of viruses and also should be useful for the study of other occult viral agents.

Biological effects of a rat monoclonal anti-mouse IFN-gamma antibody produced by in vitro immunization

This paper describes the biological effect of monoclonal antibodies to murine IFN-gamma produced by in vitro immunization with only several nanograms of rIFN-gamma. Four mAbs binding to rIFN-gamma were selected. mAb U7 was characterized in detail and shown to bind specifically to rIFN-gamma in a Western blot and to specifically inhibit the antiviral effect of rIFN-gamma and natural IFN-gamma. The activities of IFN-alpha, beta and IL2 were not affected. The M phi activating effect of both rIFN-gamma and natural IFN-gamma was also inhibited by mAb U7. Thus, we showed that it is possible to produce specific mAbs with very small amounts of cytokines by in vitro immunization.

Monoclonal antibodies specific for each of the two toxin-binding sites of Torpedo acetylcholine receptor

We have isolated and characterized 12 monoclonal antibodies (mAbs) that block the binding of alpha-bungarotoxin (alpha-BuTx) to the acetylcholine receptor (AChR) of Torpedo californica. Two of the mAbs block alpha-BuTx binding completely; the other 10 inhibit only about 50% of the binding. The mAbs that partially inhibit alpha-BuTx binding can be divided into two groups by examination of the additive effect of pairs of mAbs on toxin binding, and by analysis of competition between mAbs for binding to the AChR. These two groups of mAbs, which we have termed A and B, appear to recognize different toxin-binding sites on the same receptor. A and B mAbs were used to determine the kinetic and pharmacological properties of the two sites. The site recognized by A mAbs binds alpha-BuTx with a forward rate constant of 0.98 X 10(5) M-1 s-1, d-tubocurarine (dTC) with a KD of (6.8 +/- 0.3) X 10(-8) M, and pancuronium with a KD of (1.9 +/- 1.0) X 10(-9) M. The site recognized by B mAbs binds alpha-BuTx with a forward rate constant of 9.3 X 10(5) M-1 s-1, dTC with a KD of (4.6 +/- 0.3) X 10(-6) M, and pancuronium with a KD of (9.3 +/- 0.8) X 10(-6) M. Binding of A and B mAbs to the AChR was variably inhibited by nicotinic cholinergic agonists and antagonists, and by alpha-conotoxin. The observed pattern of inhibition is consistent with the relative affinity of the two sites for antagonists as given above but also indicates that the mAbs recognize a diversity of epitopes within each site.

Characterization of a monoclonal antibody that probes the functional domains of the glucocorticoid receptor

Monoclonal antibodies to the rat hepatic glucocorticoid receptor (GR) were produced by using 4000-fold-purified unactivated rat hepatic GR as the immunogen in an immunization in vitro. Hybridomas were screened for anti-GR antibody production by using an enzyme-linked immunosorbent assay. The antibody, 3A6, described here, is an IgM (lambda). The interaction of 3A6 with the purified GR was explored by sedimentation analysis, where a shift of the 9 S GR to a form with a higher s20,w value was demonstrated. Binding specificity and sensitivity were demonstrated by protein immunoblotting. 3A6 cross-reacted with all rat tissue glucocorticoid receptors (GRs) examined, except those of the brain. Species cross-reactivity was observed with other mammalian GRs (from human CEM-C7 cells and from pig and mouse liver). Immunocytochemical localization of the GR was assessed by indirect immunofluorescence in intact fixed cells, which demonstrated intense cytoplasmic staining in the absence of pretreatment with glucocorticoids and nuclear localization when cells were pretreated with glucocorticoids. This monoclonal antibody significantly inhibited steroid binding to unoccupied receptor and DNA binding of activated steroid-receptor complexes. Furthermore, preincubation of the purified activated GR complex with 3A6 prevented phosphorylation of the GR in vitro. Thus 3A6 differs from previous monoclonal antibodies to the GR in its capacity to cross-react with the human GR and by its specificity for an epitope on or near a functional domain of the GR.

Monoclonal antibodies to human parathyroid hormone (1-34) and their use in the immunocytochemical detection of parathyroid tumours

Monoclonal antibodies against the biologically active N-terminal fragment of human parathyroid hormone, hPTH (1-34), were produced. The procedure included the use of novel secondary immunization in vitro of mouse spleen cell cultures. Dissociated spleen cells from primary immunized Balb/c mice, were cultured for five days in the presence of thymocyte conditioned media (TCM) and synthetic hPTH (1-34). Contrary to previous findings by other workers, in our hands Balb/c mice responded well. Following immunization the spleen cells were fused with NSl myeloma cells and cultured for eleven days before screening for antibody. Using an enzyme linked immunosorbent assay (ELISA) a number of positive clones were detected. Positive cells were cloned by limiting dilution and fifteen specific monoclonal hybridomas were produced. The immunoglobulin class of the different monoclonal antibodies was found to be IgGl. The immunocytochemical reaction was tested with chief cell carcinoma tissue and found to be clearly positive.

Antibody that recognizes conformations of calmodulin in the serum from patient with chronic active hepatitis

According to the effects of Ca++ on the reactivity, anti-calmodulin antibody in the sera of patients with autoimmune chronic active hepatitis was classified into three types, which were tentatively designated as type 1, 2 and 3. Type 1 antibody reacted with calmodulin only in the presence of free Ca++. Binding of type 2 antibody to calmodulin was inhibited by the presence of free Ca++. Type 3 antibody reacted with calmodulin regardless of the presence or absence of free Ca++. Thus the sera contained the populations of the antibody which recognized the different conformations of calmodulin molecule.

Partial purification of lymphoblasts after in vitro immunization increases the yield in Ig-producing hybridomas

Using in vitro immunization with a human plasma protein (apolipoprotein-A1) as antigen, we have shown that it is possible to prepare more monoclonal antibodies using a ten-fold lower concentration of antigen compared to in vivo immunization procedures (Weech et al., 1985). In addition, we can increase the number of Ig-producing hybridomas after in vitro immunization by a simple one-step separation of the lymphoblasts on a Percoll gradient before the fusion procedure. In order to apply this procedure to in vivo immunization techniques, it is necessary to expand the B-blast/plasma cell population by culturing the spleen cells for 4-6 days before fusion. Only antibodies of the IgM class were produced with the in vitro technique. However, by combining in vivo priming with in vitro immunization, it is possible to produce specific antibodies to both IgG and IgM classes.

Production of IgG-producing hybridomas by in vitro stimulation of murine spleen cells

An in vitro stimulation protocol has been established which allows production of IgG-secreting murine hybridomas. This procedure has been examined using jack bean urease and human luteinizing hormone as antigens. Parameters which have been optimized include selection of media and serum supplements, thymocyte-conditioned media, antigen dosage, length of stimulation and the effect of medium changes during stimulation and additions of polyclonal mitogen. Murine spleen cells (1 X 10(8) in 10 ml) were incubated with varying doses of jack bean urease and human luteinizing hormone in a six-well plate in supplemented DMEM with 5% normal rabbit serum and 10% thymocyte-conditioned media. Following 5 and/or 8 days stimulation, the spleen cells were fused with SP2/0 cells and plated in 96-well plates. Stable hybridomas were obtained for both antigens from over 25% of the wells identified in initial screening for specific antibody production. All monoclonal antibodies obtained in the LH stimulation experiments, with one exception, were of the IgM isotype. A large number of IgG-producing hybridomas were isolated following prolonged (8 day) stimulation with high concentrations of urease, during which time the medium remained unchanged. Addition of polyclonal mitogen (E. coli lipopolysaccharide) at 10 micrograms/ml markedly increased the production of hybridomas secreting anti-urease, but most were of IgM class.

Development of in vitro immunization in murine and human hybridoma technology

The development of in vitro immunization in murine and human hybridoma technology is reviewed. Special consideration is given to: technical aspects of in vitro immunization of mouse B cells; quality of antibodies produced by in vitro immunization; advantages of murine in vitro immunization; technical aspects of in vitro immunization of human B cells; and the advantages of human in vitro immunization and human monoclonal antibodies. Future developments likely to be made in this area of immunotechnology are outlined.

Lymph node primary immunization of mice for the production of polyclonal and monoclonal antibodies

Primary immunization of mice by lymph node injection of bovine serum albumin (BSA) in doses as low as 1 ng followed by a secondary immunization with 1 microgram each for intraperiteonal and intravenous injections was sufficient to elicit the production of circulating antibodies. The lowest efficient dose tested was the injection of 100 ng of BSA in the lymph nodes and booster injections of 1 ng each. This method was extended to the production of monoclonal antibodies using less than 20 micrograms of a 35 kDa polypeptide purified from hamster cells transformed by Herpes simplex type 2 viruses.

Production of murine monoclonal antibodies against human thyroglobulin using an in vitro immunization procedure in serum-free medium

A serum-free in vitro immunization method for the generation of hybridomas producing specific antibodies to an antigen is described. The method was tested with human thyroglobulin as antigen. The serum-free medium used (Yssel et al., 1984) consisted of Iscove's modification of Dulbecco's modified Eagle's medium, supplemented with albumin, transferrin, insulin, ethanolamine and linoleic, oleic and palmitic acids. An optimal response was obtained when splenocytes from BALB/c mice were cultured for 3 days in the presence of 1.5 nM thyroglobulin and thymocyte-conditioned medium prior to fusion with SP2/0 myeloma cells and seeding of the fused cells in microtitre plates. The frequency of positive wells, defined as the number of wells secreting anti-(thyroglobulin) antibodies/number of viable cells used for the fusion, was 1.6 X 10(-6) +/- 0.25 X 10(-6) (mean +/- SD; n = 4). Eight stable clones producing anti-(thyroglobulin) antibodies were isolated. One clone (3D12) produced antibodies reacting only with human thyroglobulin. The antibodies produced by the other clones reacted with human, murine and porcine thyroglobulins. Seven of the clones produced antibodies of the IgM class and one clone produced IgG. The specificity of 3D12 (IgM) for human thyroglobulin and the absence of any reactivity with murine thyroglobulin provides evidence for a primary response of splenocytes in culture to the presence of an antigen.

Partial purification and characterization of protein tyrosine kinases from normal tissues

Three membranous protein tyrosine kinases (PTKs) have been partially purified from human placenta and pig brain. The two placental enzymes (PTK-1 and -2) are distinct with respect to solubility in detergents, molecular weight, and enzymatic properties. The brain protein tyrosine kinase resembles placental PTK-1 with respect to molecular weight and some kinetic properties. However, stimulation of brain PTK is greater with Mn2+ than with Mg2+ whereas placental PTK-1 gives higher rates with Mg2+ than with Mn2+. All three enzymes are inhibited about 50% by 0.1 M NaCl. A monoclonal antibody raised in vitro against the brain enzyme inhibits brain PTK as well as placental PTK-2, but has no effect against PTK-1 or pp60src. It thus appears that these three enzymes are distinct entities that differ from each other both kinetically and immunologically. With synthetic tyrosine-glutamic acid polymers as a substrate, protein tyrosine kinase activity can be detected in crude extracts of membranes.

Enhancing the establishment efficiency of hybridoma cells. Use of irradiated human diploid fibroblast feeder layers

Eight different cell feeder layers and 2 conditioned media were compared for their ability to increase the establishment efficiency of newly formed hybridoma cells. Enhancement was noted particularly with all 3 irradiated human lung diploid fibroblasts which were tested. Hybridomas established in the presence of the feeder layers were found to be stable upon propagation even in the absence of the feeder cells. MRC-5 diploid fibroblasts are suggested as the hybridoma feeder layer cell of choice due to this cell's ease of culture and handling.

Production of monoclonal antibodies against prostatic acid phosphatase by in vitro immunization of human spleen cells

Monoclonal antibodies against human prostatic acid phosphatase (PAPase) were produced by immunization of human primary spleen cell cultures. Dissociated spleen cells were cultured for 5-8 days in the presence of 100 ng/ml of PAPase and pokeweed mitogen (1:5000). Following immunization, B cells were isolated and infected with Epstein-Barr virus (EBV). Two weeks after EBV-transformation, cells were fused with either mouse myeloma cells (SP2/OAg14) or human/mouse heteromyeloma cells (SHM-D33). Hybrid clones were screened for anti-PAPase production. In 7 independent immunizations, the average fusion frequency was 3.6 per 10(6) lymphocytes. 18-32% of the hybridomas produced anti-PAPase; approximately 75% of these secreted IgM and 25% secreted IgG. Antibody specificity was determined by immunoassay and immunohistological studies. The procedures described here may be suitable for the production of human monoclonal antibody of a useful specificity.

Diversity among Purkinje cells in the monkey cerebellum

A monoclonal antibody (B1) produced against rat embryonic forebrain membranes shows specific and striking immunohistochemical staining of Purkinje cells in the monkey cerebellum in a pattern of broad parasagittal alternating bands of cells either possessing or lacking the B1 antigen. In addition, the neurons of the deep cerebellar nuclei and some neurons of the motor cortex and of the spinal cord also contain the B1 antigen. Neurons with the B1 antigen were also seen in the somatosensory cortex, the vestibular and cochlear nuclei, and the retina.

Optimization of conditions for in vitro antigenic stimulation of dissociated mouse spleen cells for the production of monoclonal antibodies against peptide hormones

Factors affecting hybridoma yield following in vitro immunization have been investigated. Of critical importance for optimum yield was the batch of young calf serum used both in immunization cultures and in post-fusion cultures. Only 1 batch of serum was found to be suitable for the immunization step. The addition of horse serum to deficient young calf serum in pre-fusion cultures did not reconstitute the essential component(s). Addition of T cell, macrophage and bovine endothelial cell conditioned medium to the supportive batch of young calf serum in pre-fusion cultures did not increase the yield of hybridomas. For one antigen (insulin) the yield of hybrid cells was dependent on the concentration of antigen in immunization cultures. This was not the case, however, with the second antigen (ACTH) within the concentration range examined. The optimum spleen cells density was 1 X 10(7) cells/ml and the optimum culture period before fusion was 5-6 days. Although in vivo priming followed by in vitro boosting decreased the yield of hybrids the relative percentage of positive hybrids was slightly increased. The results suggest that in vivo priming is not essential since primary in vitro stimulation alone produced significant numbers of hybrids secreting specific antibody.

A statistical approach to determine monoclonality after limiting cell plating of a hybridoma clone

One of the standard methods to isolate a hybridoma clone producing a monoclonal antibody requires successive steps of limiting dilution. The probability of obtaining a monoclonal antibody increases with the number of limiting dilution steps. However, without meticulous visual screening monoclonality is hard to prove. Here we describe a statistical analysis, based on Poisson's approximation, which allows one to calculate the number of hybridoma cells at a given plating efficiency so that when seeded a predictable number of mono-, bi-, etc.-clonal cultures are obtained after the first step of limiting cell plating.

Monoclonal antibodies against chicken tropomyosin isoforms: production, characterization, and application

Eight mouse monoclonal antibodies, CH1, CH106, CH291, CL2, CG1, CG3, CG beta 2 and CG beta 6, against chicken tropomyosin isoforms have been prepared and characterized. The antigens recognized by these isoform-specific monoclonal antibodies were identified by both solid-phase radioimmunoassay and protein immunoblotting. To some extent, most antibodies showed isoform-specific, but one (CG3) recognized all isoforms of tropomyosin from chicken materials. The effects of monoclonal antibodies on the binding of cardiac tropomyosin to F-actin were investigated. Antibodies CH1, CH106, and CH291 had the ability to interfere with the binding of tropomyosin to F-actin, whereas others appeared to have no effect. Monoclonal antibody CL2 was able to distinguish the skeletal muscle tropomyosin-enriched microfilaments from the fibroblastic tropomyosin-enriched microfilaments of differentiating muscle cells. This antibody will be most useful for studying the compartmentalization of microfilaments and microfilament-associated proteins, particularly actin and tropomyosin isoforms during muscle differentiation. Immunofluorescence microscopy with CG1 antibody which recognized CEF tropomyosin isoforms 1 and 3 revealed the continuous staining of stress fibers in some populations of CEF cells. On the other hand, both periodic fluorescent staining and continuous staining of stress fibers were observed with CG3 antibody in all CEF cells.