Sperm-Immobilizing Antibodies Block Capacitation in Human Spermatozoa

Abstract

Sperm-immobilizing antibodies block human fertilization by interfering with the acrosome reaction (AR). To clarify the mechanism of blockage of AR by sperm-immobilizing antibodies, the authors examined their effects on the increase of intracellular free Ca2+ concentration induced by follicular fluids (Ca2+ influx) in spermatozoa and on their capacitation. Sperm-immobilizing antibodies did not suppress Ca2+ influx induced by follicular fluid, but they inhibited capacitation of human spermatozoa. Namely delta%AR (%AR after addition of an AR inducer--%AR before treatment) induced by progesterone was significantly (p < .0001) lower when spermatozoa were incubated in human tubal fluid medium cotaining antibody-positive serum (1.2%), compared to that when incubated in control medium (19.2%). Furthermore, the proportion of both spermatozoa that became capacitated and ones that had become capacitated decreased significantly (p < .0001) after 2, 4, and 6 h of incubation in medium containing antisperm antibody-positive serum, compared to those of spermatozoa incubated in control medium. In conclusion, sperm-immobilizing antibodies may be closely related to their blockage of capacitation.

Unexplained Male infertility: diagnosis and Management

“…Complement in female cervical mucus can bind to antibodies and cause lysis of the sperm cell, reducing motility and inhibiting the ability of sperm to penetrate cervical mucus (28)(29)(30). Evidence suggests ASA cause sperm to have lower rates of spontaneous and induced acrosome reaction compared to sperm in ASA absent serum (31,32). Certain ASA have also been shown to inhibit spontaneous sperm capacitation reaction, and there is evidence to suggest that ASA can interfere with recognition of sperm binding sites on the zona pellucida (28).…”

Increased Level of Antibodies Cross-Reacting with Ves v 5 and CRISP-2 in MAR-Positive Patients

“…The effects of ASA on sperm functions are very heterogeneous, as they may impair different steps of the fertilization process. ASA are described to reduce cervical mucus penetration [1,2], reduce or increase capacitation and acrosome reaction [3,4], inhibit the binding of the zona pellucida [5,6] and oolema binding, and affect the sperm-egg fusion [7,8] and the embryonic development, implantation and miscarriages [9,10]. …”

Proteomic discovery of diverse immunity molecules in mammalian spermatozoa

“…Given their potential role in immunological infertility, much attention has been focused on identifying integral sperm proteins that serve as targets for sperm inactivation [Bohring and Krause 2003;Paradowska et al 2006]. Although the prevalence and overall significance of this disorder is still debated, it is believed that ASA bound to the sperm membrane have the potential to influence sperm function and fertility [Bohring and Krause 2005a;2005b;Goldstein and Rosenwaks 2009;Myogo et al 2001;Vazquez-Levin et al 1997]. Prior to the application of mass spectrometry based proteomics to the study of sperm composition, ASA were useful in identifying integral sperm proteins, including HSP70, HSP70-2, disulphide isomerase, ER60, caspase 3, and protoeosome complex subunits [Bohring et al 2001].…”