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Department of Pathology, University of California, San Diego, CA (LBC); Department of Population Health and Reproduction (LBC, CMC, RHB) and Department of Pathology, Microbiology and Immunology (MLA, LJG, LM, DWA), University of California, Davis, CA; and National Wildlife Research Center, Fort Collins, CO (JCR)
We showed earlier that Tritrichomonas foetusspecific bovine immunoglobulin (Ig)G1 and IgA antibodies in uterine and vaginal secretions are correlated with clearance of this sexually transmitted infection. Eosinophils have been noted in previous studies of bovine trichomoniasis but the role of mast cells and IgE responses have not been reported. The hypothesis that IgE and mast cell degranulation play a role in clearance was tested in 25 virgin heifers inseminated experimentally and infected intravaginally with T. foetus strain D1 at estrus and cultured weekly. Groups were euthanatized at 3, 6, 9, or 12 weeks, when tissues were fixed and secretions were collected for culture and antibody analysis. Immunohistochemistry using a monoclonal antibody to a soluble lipophosphoglycan (LPG)containing surface antigen (TF1.17) demonstrated antigen uptake by uterine epithelial cells. Lymphoid nodules were detected below antigen-positive epithelium. Little IgG2 antibody was detected but IgG1, IgA, IgM, and IgE T. foetusspecific antibodies increased in uterine secretions at weeks 6 and 9 after infection. This was inversely proportional to subepithelial mast cells numbers and most animals cleared the infection by the sampling time after the lowest mast cell count. Furthermore, soluble antigen was found in uterine epithelium above inductive sites (lymphoid nodules). Cross-linking of IgE on mast cells by antigen and perhaps LPG triggering appears to have resulted in degranulation. Released cytokines may account for production of predominantly Th2 (IgG1 and IgE) and IgA antibody responses, which are related to clearance of the infection.
Key words: Antibodies; bovine disease; IgE; mast cells; Tritrichomonas foetus; uterus.
Request reprints from Dr. L. B. Corbeil, Department of Pathology, UCSD Medical Center, 200 West Arbor Drive, San Diego, CA 92103-8416 (USA). E-mail: lcorbeil{at}ucsd.edu
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