Sperm-immobilizing antibodies block capacitation in human spermatozoa.
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.
Myogo
K
K
Department of Obstetrics and Gynecology, School of Medicine, The University of Tokushima, Japan.
Yamano
S
S
Nakagawa
K
K
Kamada
M
M
Maegawa
M
M
Irahara
M
M
Aono
T
T
D020101:Acrosome Reaction / Q000187:drug effects / Q000276:immunology; D000906:Antibodies / Q000276:immunology*; D002118:Calcium / Q000378:metabolism; D006801:Humans; D017136:Ion Transport; D008297:Male; D011374:Progesterone / Q000494:pharmacology; D013075:Sperm Capacitation / Q000276:immunology*; D013094:Spermatozoa / Q000276:immunology / Q000378:metabolism / Q000502:physiology*
D000906:Antibodies; D011374:Progesterone; D002118:Calcium