Bovine x mouse hybridomas that secrete bovine immunoglobulin G1.

The interspecific fusion of normal bovine lymphocytes with a nonsecreting mouse hybridoma produced stable cell lines secreting bovine immunoglobulins. One of these lines has continued to secrete immunoglobulin G1 (5 to 10 micrograms per milliliter) for over 16 months. The bovine x mouse hybrid cells can be expected to provide bovine monoclonal immunoglobulins for sequencing studies and for use as serological standards as well as to provide messenger RNA for cloning bovine immunoglobulin genes.

Epitope ratio analysis (ERA): a simple radioimmunological method using monoclonal antibodies for the simultaneous analysis of several antigens.

Monoclonal antibodies specific for human cell surface antigens were used to develop a technique for the simultaneous analysis of several antigenic determinants. The procedure was used to measure the relative expression of specific cell antigens during cultural growth. Epitope ratio analysis (ERA) is applicable to many systems requiring measurement of such differential antigen expression.

Immunoglobulin VH usage analysis by fluorescent in situ hybridization and flow cytometry.

We have devised a flow cytometry-based fluorescent in situ hybridization assay that permits analysis of gene expression in a large number of single cells. In this technique, fixed and permeabilized cells are incubated with biotinylated single-stranded RNA probes and by means of a fluorescently labelled second-step reagent, the cells are analyzed by flow cytometry. This is a rapid and simple method that allows all of the steps in the procedure to be performed on cells in suspension. Using this approach, we demonstrate here that immunoglobulin heavy chain variable region (VH) gene expression can be analyzed among individual cells using particular VH family-specific probes. This technique has a high degree of accuracy (greater than 97%) in detecting the fraction of cells expressing a specific message in a population and is sensitive enough to detect immunoglobulin message in LPS activated B cells. The technique has been applied successfully to monitor gene expression in homogeneous and heterogeneous populations. It also allows concurrent analysis of cell surface proteins and gene expression through two-color flow cytometry. This method of monitoring gene expression in individual cells may have a number of applications in immunology and cell biology.

Comparative idiotype network interactions: antigen mimicry by an anti-bovine idiotype monoclonal antibody in rats and cattle.

Idiotype/anti-idiotype networks have been extensively investigated in such conventional animal models as the mouse and the rabbit. However, systems of veterinary interest have remained largely unexplored. A monoclonal target idiotype, with which to begin such studies in cattle was provided by LHRB 19.17 an interspecific bovine x mouse hybridoma. This hybridoma was constructed by the fusion of supramammary lymph node cells from S. agalactiae-immunized lactating Holsteins with the Ig synthesis-permissive established cell line, SP 2/0. Two collections of monoclonal anti-idiotype antibodies were generated by fusion of spleen cells from LHRB 19.17-immunized Balb/c or A/J mice immunized with the monoclonal bovine idiotype, LHRB 19.17. Many of the anti-idiotypes inhibited binding of LHRB 19.17 to S. agalactiae, but only one, LHRAID 2.71, proved to be an internal image of a S. agalactiae epitope. Immunization of C/D outbred rats by priming with 100-300 micrograms of LHRAID 2.71 emulsified in CFA followed by a 300 micrograms boost at day 32 elicited anti- S. agalactiae antibody in 4/4 animals tested. Similarly, the injection of two lactating Holsteins with the anti-id resulted in the production of anti- S. agalactiae antibody in serum and milk. In both rats and cattle, the administration of the antigen-mimicking anti-idiotype induces the appearance of S. agalactiae-reactive horseradish peroxidase-streptavidin conjugate; LHRBs, interspecific bovine x mouse hybridomas secreting bovine Ig; LHRAID.X, monoclonal anti-bovine idiotype antibodies derived against LHRB 19.17; PBS, phosphate buffered saline; PBS/BSA, PBS containing 0.1% bovine serum albumin: antibody [AB3] that competes with LHRB 19.17 [AB1] for binding to LHRAID 2.71 [AB2]. It should also be noted that the immunization of C/D rats with S. agalactiae does not result in the appearance of idiotypes which compete with LHRB 19.17 for binding to LHRAID 2.71. We have concluded that immunization of two widely divergent species with the antigen mimicking LHRAID 2.71 induced a S. agalactiae-reactive idiotype which was not detectable in the immune response of rats to S. agalactiae.

Immunoglobulin gene diversification in cattle.

Research in several species has revealed that different types of mammals have evolved divergent molecular and cellular strategies for generating immunoglobulin diversity. Other chapters in this text have highlighted the specific characteristics unique to chicken, rabbit, mouse, human and sheep B lymphocyte development; namely indicating differences in the mechanisms of diversity and the site of primary B cell development. Studies of the bovine system have indicated that like the sheep system, the ileal Peyer's patch (IPP) is a likely chicken bursal equivalent, and is a site of primary B lymphocyte development. Substantial investigation in sheep has indicated that Ig diversity is created by untemplated somatic mutation and intense selective pressure (Reynaud et al., 1991). The frequency of alteration in the sheep Ig light chain gene locus also is characteristic of the bovine system, however, recent evidence from sequencing of bovine lambda light chain genes indicates that one mechanism that contributes to diversity is gene conversion, utilizing several pseudogenes located in the Ig locus (Parng et al., 1996). The mechanism by which this hyperalteration of Ig genes occurs in both sheep and cattle is poorly understood and is thus the focus of considerable investigation. The study of events in the IPP may also have informative ramifications for secondary diversification of the Ig repertoire by somatic hyperalteration in germinal centers.

Immunoaffinity chromatography of bovine FSH using monoclonal antibodies.

Bovine FSH (bFSH) was used to immunize BALB/c mice. Spleen cells were fused to the SP 2/0 cell line to produce hybridomas that secreted monoclonal antibodies to bFSH. One of these antibodies (USDA-bFSH-MC28) was extensively characterized and found to be a gamma 1 with kappa light chains, having extremely low cross-reactivity with other bovine pituitary hormones and with ovine and porcine FSH. The dissociation constant as measured by Scatchard analysis was 4.3 nmol/l, and proved to be in a very useful range for affinity chromatography. In an essentially one-step immunoaffinity chromatography procedure, bFSH was easily isolated in a single chromatographic step from crude anterior pituitary homogenate with better yield and with the same purity as classical chromatographic techniques.

Production and characterization of monoclonal bovine immunoglobulins G1, G2 and M from bovine x murine hybridomas.

Three bovine x murine hybridomas, which secrete bovine IgG1, IgG2 and IgM, respectively, were derived by the fusion of normal bovine B lymphocytes to the murine cell line SP-2/0. The hybridomas were initially selected by testing the culture supernatant of individual clones with rabbit anti-bovine light chain antibody. The bovine nature of Ig secreted by the bovine x murine hybridomas was confirmed by the ability of bovine serum but not murine serum to inhibit specific adsorption by murine anti-bovine Ig coupled to Sepharose 4B and the inability of sheep anti-mouse Ig (all isotypes) to bind biosynthetically labelled Ig from the respective bovine x murine hybridomas or to react with bovine x murine hybridoma Ig in Ouchterlony analysis. The isotype of the bovine Ig produced by each hybridoma was determined by cRIA using bovine Ig isotype-specific murine mcab, Ouchterlony analysis with guinea pig anti-bovine Ig isotypes and molecular weight analysis of unreduced and reduced affinity purified Ig from the respective bovine x murine hybridomas. Even though the hybridomas in this study showed chromosome loss, they have continued to secrete bovine Ig in culture for over 16 months, indicating that it is possible to isolate and stabilize interspecific hybridomas retaining the chromosome, or at least the genes, encoding an Ig. These hybridomas will provide monoclonal bovine Ig for; 1) serological standards, 2) production of polyclonal and monoclonal antisera to bovine Ig isotypes, 3) sequencing studies, 4) serological and structural studies of bovine Ig classes and subclasses, and messenger RNA for the production of cDNA probes for the cloning of bovine Ig genes and for determining the organization of Ig genes in the bovine genome.

The application of hybridoma technology to the study of bovine immunoglobulins.

Studies are described in which hybridoma technology is used to produce a variety of reagents for the characterization and manipulation of the bovine humoral immune system. Selected members of a set of murine monoclonal antibodies (MAb) specific for each of four major isotypes of bovine Ig constant regions, one specific for anti-bovine Ig constant regions as well as one specific for anti-bovine light chains are discussed. Interspecific fusion of bovine lymphocytes with the established mouse cell line, SP2/0 was used to produce a collection of stable hybridomas among which were found secretors of bovine IgG1, IgG2, IgM, IgA and bovine light chain. Interspecific fusion of SP2/0 with lymphocytes from a multiparous Holstein four days post immunization with Streptococcus agalactiae yielded MAb with specificity for the immunizing antigen. One of these hybridomas, LHRB 19.17, which displayed a particularly stable secretory phenotype, was used as an immunogen for the production of a library of murine monoclonal anti-idiotype antibodies. Competitive antigen binding analysis showed that 15 of the 24 anti-LHRB 19.17 idiotype antibodies isolated blocked the binding of the idiotype to its nominal antigen and so were candidates for evaluation as antigen mimics. Some of the ways in which monoclonal anti-idiotypes in particular, and monoclonal in general, might be of use in problems of animal disease are discussed.

Biotechnology: a selective survey.

Biotechnology is a selective amalgam of the ideas and techniques of many fields, particularly biochemistry, microbiology, genetics, and developmental biology. The identifying signature of biotechnology is the calculated manipulation, modification, and even creation of new genetic entities. This review examines such aspects of biotechnology as: (a) the analysis and cloning of DNA; (b) the production of transgenic organisms and some speculations on the use of this technology in animal husbandry; and (c) the construction and uses of monoclonal-antibody-secreting hybridomas.

Salmonella enteritidis-specific monoclonal antibodies.

Three monoclonal antibodies (MAbs) were derived that are specific for Salmonella enteritidis. Such antibodies are of interest because reagents that specifically identify S. enteritidis are potentially useful for the diagnosis and detection of this pathogen. Immunization of BALB/c mice with intact, unfixed, ultraviolet-killed S. enteritidis permitted the derivation of a collection of hybridomas among which were found three MAbs: 1053, 1110, and 1170. Each MAb reacted with six independent field isolates of S. enteritidis, including phage type 4. However, none of these S. enteritidis-specific MAbs reacted with any of the following members of a broad diversity of Salmonella species: S. typhimurium, S. pullorum, S. berta, S. agona, S. dublin, S. miami, S. heidelberg, S. montevideo, S. senftenberg, and S. schwarzengrund. The S. enteritidis-specific determinant recognized by these MAbs is heat-labile, and preliminary experiments indicate that at least two of the MAbs recognize the same determinant.

Production and characterization of monoclonal antibodies to bovine immunoglobulin G2.

Spleen cells from Balb/cJ mice inoculated with bovine immunoglobulin (Ig)G were hybridized with hypoxanthine aminopterin thymidine-sensitive nonsecreting cell line SP-2/0, and the hybrid cell culture fluid was tested for specificity. Hybrid cells secreting monoclonal antibodies to bovine IgG were isolated and recloned. The monoclonal antibody DAS 2 was specific for bovine IgG2 by an indirect solid-phase radioimmunoassay. This clone was adapted for growth as antibody-secreting neoplasms in Balb/cJ mice, the sera from which contained high titers (1:128,000) of anti-bovine IgG2 antibodies. Antibody specific to bovine IgG2 was isolated by affinity chromatography. This antibody was shown by Ouchterlony analysis to be mouse IgG1 with the kappa light chain. On isoelectric focusing, this antibody gave a pattern that was consistent with monoclonality.

Production and characterization of monoclonal antibodies to bovine beta 2-microglobulin.

In an attempt to isolate monoclonal antibodies specific for bovine lymphocytes, spleen cells from mice immunized with bovine lymphocytes were fused with the mouse myeloma cell line SP-2/0. The resulting hybridoma cell lines were tested for reactivity with bovine lymphocytes, polymorphonuclear neutrophils, RBC, gamma-globulin, kappa-casein, beta-casein, alpha-S1-casein, and beta 2-microglobulin (beta 2m) and with beta 2m from rabbits, goats, and human beings. None of the clones secreted anti-bovine lymphocyte-specific antibody. However, 4 secreted monoclonal antibodies to bovine beta 2m. They also reacted with beta 2m from rabbit, goat, and human being. One monoclonal antibody also was found to be reactive with bovine immunoglobulin. Monoclonal antibodies to beta 2m could serve as a tool to (1) explore the homology of the beta 2m molecule among various species, (2) examine the relationship of beta 2 m with the constant region of the immunoglobulin molecule, (3) quantitate bovine beta 2m in various body fluids and major histocompatibility antigens on cell surfaces, (4) help characterize those antigens in cattle, and (5) be used for tissue typing of those antigens.