Immunoglobulins and immunoglobulin‐containing cells in the reproductive tracts of rams naturally infected with Brucella ovis

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Abstract
SUMMARY Thirteen rams with serological evidence of Brucella ovls exposure (CFT of 1:8 or greater), but with no or only mild epididymitis, were selected from a ram flock. Serum, semen, preputial washings and fluids from the accessory sex glands (ASGF) and testis and epididymis (TEF) were examined and immunoglobulin (lg) concentrations estimated. Genital tissues were examined histologically and the percentages of class specific immunoglobulin containing cells (ICC) determined. Eleven of these rams had histological evidence of active inflammation consistent with B. ovis infection; the organisam was cultured from the semen of 7. IgA concentration was high in semen (mean ± standard deviation of 5.03 ± 1.78 mg/ml) and ASGF (9.18 ± 7.28 mg/ml). These levels were much higher than those recorded in noninfected rams. IgA concentration was low in serum (0.78 ± 0.55 mg/ml) and TEF (0.59 ± 0.78 mg/ml). The concentrations of IgG1, IgG2, and IgM were low in all genital fluids sampled and not significantly different from those recorded in noninfected rams. This indicated that infection with B. ovis results in a pronounced IgA response in secretions, mostly from the accessory sex glands. Examinations of ICC, however, revealed that the plasma cell infiltrates of the epididymis, vas deferens, ampulla and seminal vesicle were predominantly IgG-containing (92.4, 97.2, 79.4 and 91.9% respectively). Fewer IgM-containing cells were scattered throughout these tissues, constituting 3.9, 6.3, 0.3 and 6.5% of all ICC, respectively. IgA-containing cells were most frequently seen in the ampulla (9.6% of ICC) where they were located directly beneath the epithelium, suggesting the ampulla as the most prominant location for the local production of IgA. These results indicate that although the tissue ICC response was predominantly IgG, IgA was selectively transferred into secretions with the exclusion of most IgG and IgM. ICC percentages in bulbourethral and prostate glands, and beneath pelvic urethral and preputial epithelia, were similar to those found in noninfected rams.