Production and use of murine monoclonal antibodies reactive with bovine IgM isotype and IgG subisotypes (IgG1, IgG2a and IgG2b) in assessing immunoglobulin levels in serum of cattle

Monoclonal antibody to the light chain of bovine immunoglobulin

Monoclonal antibody IVA-285 (IgG1 isotype) recognizing antigenic determinant on bovine and ovine immunoglobulin light chain was produced and characterized. Western blot analysis of bovine immunoglobulin G (IgG) and immunoglobulin M (IgM) purified from bovine blood serum as well as whole immunoglobulin fractions of bovine and ovine serum with IVA-285 showed a molecular weight in the 24-27 kd range corresponding to the Ig light chain of bovine Ig. IVA-285 recognizes the Ig light chain on Ig+ lymphocyte subpopulation and in the majority of body fluids; however, especially strong reactions were observed in bovine tissues (lymph node follicles, plasma cells, and Ig deposits in various tissues).

The bovine antibody repertoire

Cattle are able to produce a full range of Ig classes including the long-elusive IgD through rearrangement of their germline genes. Several IgL groupings have been reported but as in several other livestock species (e.g. sheep, rabbits, chickens), rearrangement per se fails to generate significant IgH diversity. This is largely because of the modest number of bovine VH segments that participate in rearrangement and their conserved sequences. Perhaps in compensation, bovine Ig heavy chains carry CDR3 sequences of exceptional length. Processes that operate post-rearrangement to generate diversity remain ill defined as are the location, timing and triggers to these events. Reagents are needed to understand better the maturation of B lymphocytes, their responses to antigens and cytokines, and to provide standards for the quantitation of Ig responses in cattle; recombinant methods may help meet this need as Ab engineering technologies become more widely used.

Effects of type I/type II interferons and transforming growth factor-beta on B-cell differentiation and proliferation. Definition of costimulation and cytokine requirements for immunoglobulin synthesis and expression

In this report, we sought to determine the role of selected type I interferons [interferon-alpha (IFN-alpha) and interferon-tau (IFN-tau)], IFN-gamma and transforming growth factor-beta (TGF-beta) in the regulation of bovine antibody responses. B cells were stimulated via CD40 in the presence or absence of B-cell receptor (BCR) cross-linking. IFN-alpha enhanced IgM, IgG2 and IgA responses but did not enhance IgG1 responses. BCR signalling alone was more effective at inducing IgG2 responses with IFN-alpha than dual cross-linking with CD40. Recombinant ovine IFN-tau was less effective at inducing IgG2 responses when compared with IFN-alpha, though IgA responses were similar in magnitude following BCR cross-linking. At higher concentrations, IFN-tau enhanced IgA responses greater than twofold over the levels observed with IFN-alpha. Previous studies have shown that addition of IFN-gamma to BCR or pokeweed mitogen-activated bovine B cells stimulates IgG2 production. However, following CD40 stimulation alone, IFN-gamma was relatively ineffective at stimulating high-rate synthesis of any non-IgM isotype. Dual cross-linking via CD40 and the BCR resulted in decreased synthesis of IgM with a concomitant increase in IgA and similar levels of IgG2 production to those obtained via the BCR alone. We also assessed the effects of endogenous and exogenous TGF-beta on immunoglobulin synthesis by bovine B cells. Exogenous TGF-beta stimulates both IgG2 and IgA production following CD40 and BCR cross-linking in the presence of IL-2. Blocking endogenous TGF-beta did not inhibit the up-regulation of IgG2 or IgA by interferons.

Production of monoclonal antibodies to six isotypes of horse immunoglobulin

Stable clones of 18 mouse hybridomas that produce monoclonal antibodies (MAbs) to six isotypes of horse immunoglobulin were produced. The number of hybridomas of different specificities are: four to IgGa, four to IgGb, one to IgGc, four to IgG(T), two to IgM, and three to IgA. The immunoglobulin isotypes purified from affinity columns bound with each MAb showed variable mobility in agarose-gel electrophoresis. Migration proceeded from the anode as: IgG(T), IgA, IgM, IgGc, IgGb and IgGa. The purified isotypes also demonstrated a single precipitin line when in immunoelectrophoresis against isotype-specific or polyclonal antisera, raised against the purified isotype or whole equine serum, respectively.

An arthroconidial-spherule antigen of Coccidioides immitis: differential expression during in vitro fungal development and evidence for humoral response in humans after infection or vaccination

A 33-kDa protein antigen purified from spherules of Coccidioides immitis was analyzed for ultrastructural localization and for binding to serum antibodies from infected or immunized humans. By using colloidal gold detection of affinity-purified anti-33-kDa protein antibodies, electron photomicrographs showed binding to the inner cell wall of arthroconidia and spherules and to the septa and glycocalyx surrounding endospores. Enzyme immunoassay measurements also demonstrated that the antigen was most abundant in mature spherules. Of 37 patients with coccidioidomycosis but without concurrent human immunodeficiency virus infections, all but 2 demonstrated immunoglobulin M (IgM) (usually with early infection) or IgG antibodies for the 33-kDa antigen. In contrast, only one of four HIV-infected patients with active coccidioidal infections demonstrated antibody. On the other hand, 107 of 108 patients without evident coccidioidomycosis and 15 of 16 patients with histoplasmosis did not have similar antibodies, indicating a high degree of specificity. Immunization of humans with a spherule vaccine produced IgM responses to this antigen that were not evident in placebo recipients.

Comparative mapping of IGHG1, IGHM, FES, and FOS in domestic cattle

The immunoglobulin genes have not been genetically characterized as thoroughly in cattle as in other mammals, particularly humans and mice. Comparative gene mapping in mammals suggests that the bovine immunoglobulin heavy chain genes, IGHG4 and IGHM might be syntenic with the FOS oncogene. Interestingly, however, when these genes were assigned to bovine syntenic groups utilizing a panel of bovine: hamster hybrid somatic cells, IGH genes were shown to be syntenic with the FES oncogene rather than FOS. In this study IGH and FES were assigned to Bos taurus chromosome 21 while FOS was assigned to chromosome 10. In addition, bovine-specific immunoglobulin-like sequences were observed in the hybrid somatic cells, and one, IGHML1, was mapped to bovine syntenic group U16. The probes used for somatic-cell mapping were also used to screen a small number of cattle of several different breeds for restriction fragment length polymorphisms. IGHG4 and IGHM were shown to be highly polymorphic, while FOS and FES were not.

An immunoreactive apoglycoprotein purified from Coccidioides immitis

Deglycosylation of glycoproteins in a lysate of spherules of Coccidioides immitis has permitted purification and partial characterization of a proline-rich pronase-sensitive antigen. Moreover, soluble antigen specifically stimulated lymphocytes from persons with dermal delayed-type hypersensitivity to coccidioidal antigens. When related to reference coccidioidin by tandem two-dimensional immunoelectrophoresis, the antigen fused in the anodal region with a specific reference antigen (antigen 2). It did not show identity with coccidioidal antigens used in conventional serologic assays. Although immunoblots of the purified protein with monospecific rabbit antiserum showed a single antigen at 33 kDa, the parent spherule lysate bound the same antibody in a broad band between 70 and greater than 200 kDa, which could be explained by microheterogeneity of glycosylation. Immunoelectron microscopy using affinity-purified human antibodies localized the antigen to the cell wall and internal septa of spherules. These findings suggest that the apoglycoprotein may be important in human immune responses to coccidioidal infection.