Presence of sperm-bound antisperm antibodies and their association with semen quality in dogs.

Abstract

Autoimmune orchitis (AO) is the main cause of non-obstructive azoospermia in dogs. Because AO is diagnosed in humans by the presence of antisperm antibodies (ASAs), studies aimed at understanding ASAs would benefit infertility investigation in dogs. The objectives here were to determine: 1. the prevalence of ASAs in dogs and their association with semen quality, 2. the effect of ASAs on longevity of cooled sperm motility, 3. the presence of ASAs in prostatic fluid. Presence of IgA- and IgG-bound sperm was evaluated in 67 dogs using flow cytometry. In 55 dogs, sperm motility was evaluated at 24 and 48&#xa0;h of cold storage. Last, prostatic fluid from eight ASA-positive and nine ASA-negative dogs were incubated with sperm from two healthy donors, and binding of ASAs to sperm was evaluated using flow cytometry (indirect immunofluorescence test). The percentage of IgA- (P&#xa0;=&#xa0;0.037) and IgG-bound (P&#xa0;=&#xa0;0.031) sperm was higher in dogs failing the breeding soundness exam (unsatisfactory breeders) (n&#xa0;=&#xa0;56) than in dogs passing the exam (satisfactory breeders) (n&#xa0;=&#xa0;11). Ten dogs (14.9%, 10/67) had IgA-positive ejaculates (&#x2265;10% IgA-bound total, live or dead sperm), 40% of which also had concurrent IgG binding. The frequency of ASA-positive (&#x2265;10% IgA- or IgG-bound total, live or dead sperm) samples was 17.9% (10/56) in unsatisfactory breeders and 0% in satisfactory breeders. ASA-positive dogs had lower sperm concentration (P&#xa0;=&#xa0;0.029), total motile sperm count (P&#xa0;=&#xa0;0.021), and neutrophils (P&#xa0;=&#xa0;0.028) than ASA-negative dogs. Cooled sperm from ASA-positive dogs had lower motility at 24 and 48&#xa0;h compared with ASA-negative dogs (P&#xa0;<&#xa0;0.05). Of all dogs with sperm-bound IgA in raw semen, only 37.5% had IgA in the prostatic fluid that bound to sperm from healthy donors (P&#xa0;=&#xa0;0.09). None of the IgG-positive dogs yielded an IgG-positive result in the indirect tests (P&#xa0;=&#xa0;0.042). All dogs with no ASA-bound sperm in raw semen tests remained ASA-negative on the indirect tests. In summary, ASAs were present in 18% of unsatisfactory breeder dogs associated with oligospermia, teratospermia and poor cooling ability. The binding of ASAs to the sperm occurred within the testis and/or epididymis, with no IgG and little IgA present in the prostatic fluid. The characteristics of the ASA-positive ejaculates resembled those from dogs with AO. Testing dogs with oligospermia, teratospermia and poor cooling ability for presence of ASAs may provide an early and non-invasive marker of possible AO or immune-mediated infertility.