Use of flow cytometry to characterize immunodeficiency syndromes in camelids

Production of a monoclonal antibody against serum immunoglobulin M of South American camelids and assessment of its suitability in two immunoassays

A monoclonal antibody (mAb) was produced against immunoglobulin M (IgM) of South American camelids. A single radial immunodiffusion (SRID) assay and a competitive enzyme-linked immunosorbent assay (ELISA) were developed to measure IgM in serum samples. Isotype and specificity of the mAb were assessed. The performance of the SRID assay was preliminarily evaluated in terms of working range, plate stability over a 4-week period, and initial intra- and interassay variation. The concentration of IgM was determined in 55 samples by SRID assay and ELISA, and results were not significantly different by t-test (0.64 ± 0.19 mg/ml for the SRID assay, and 0.58 ± 0.24 mg/ml for ELISA; P = 0.1489). The mAb was shown to be stable over the 4-week evaluation period, and the SRID assay was reproducible when tested in triplicate for intra-assay variability and in quadruplicate for interassay variability, with a percentage coefficient of variation of less than or equal to 5%. Also, the SRID assay proved to be sensitive enough to measure IgM levels in undiluted serum samples, and had a good correlation with ELISA. The current study is intended to submit a preliminary report of a mAb against IgM of South American camelids, and suggest the future potential of the mAb developed for diagnostic application, including use in the SRID assay.

Tuberculosis immunity: opportunities from studies with cattle

Mycobacterium tuberculosis and M. bovis share >99% genetic identity and induce similar host responses and disease profiles upon infection. There is a rich history of codiscovery in the development of control measures applicable to both human and bovine tuberculosis (TB) including skin-testing procedures, M. bovis BCG vaccination, and interferon-γ release assays. The calf TB infection model offers several opportunities to further our understanding of TB immunopathogenesis. Recent observations include correlation of central memory immune responses with TB vaccine efficacy, association of SIRPα⁺ cells in ESAT-6:CFP10-elicited multinucleate giant cell formation, early γδ T cell responses to TB, antimycobacterial activity of memory CD4⁺ T cells via granulysin production, association of specific antibody with antigen burden, and suppression of innate immune gene expression in infected animals. Partnerships teaming researchers with veterinary and medical perspectives will continue to provide mutual benefit to TB research in man and animals.

Use of flow cytometry to develop and characterize a set of monoclonal antibodies specific for rabbit leukocyte differentiation molecules

Flow cytometry was used to identify and characterize monoclonal antibodies (mAbs) that react with rabbit leukocyte differentiation molecules (LDM). Screening sets of mAbs, developed against LDM in other species, for reactivity with rabbit LDM yielded 11 mAbs that recognize conserved epitopes on rabbit LDM orthologues and multiple mAbs that recognize epitopes expressed on the major histocompatibility class I or class II molecules. Screening of mAbs submitted to the Animal Homologues Section of the Eighth Human Leukocyte Differentiation Workshop yielded 7 additional mAbs. Screening of mAbs generated from mice immunized with leukocytes from rabbit thymus or spleen or concanavalin A activated peripheral blood and/or spleen lymphocytes has yielded 42 mAbs that recognize species restricted epitopes expressed on one or more lineages of leukocytes. Screening of the anti-rabbit mAbs against leukocytes from other species yielded one additional mAb. The studies show that screening of existing sets of mAbs for reactivity with rabbit LDM will not be productive and that a direct approach will be needed to develop mAbs for research in rabbits. The flow cytometric approach we developed to screen for mAbs of interest offers a way for individual laboratories to identify and characterize mAbs to LDM in rabbits and other species. A web-based program we developed provides a source of information that will facilitate analysis. It contains a searchable data base on known CD molecules and a data base on mAbs, known to react with LDM in one or more species of artiodactyla, equidae, carnivora, and or lagomorpha.