Five monoclonal antibodies (MAb) with specific binding for tail, midpi
ece, equatorial region, and postacrosome of human sperm were selected.
The reactivity of the MAbs was tested by three techniques: an ELISA w
ith human sperm, an indirect immunostaining analyzed by a cell sorter,
and immunofluorescence on the cell where the antigens were localized.
The localization or exposure of the antigens changes throughout the i
n vitro capacitation. These antigens are distributed among other mamma
lian species: mouse, ram, and goat. Their presence was also analyzed i
n some human tissues: peripheral blood mononuclear cells, spleen, panc
reas, thyroid, heart, skin, intestine, and lung. No cross-reactivity w
as detected. Some of the MAbs showing tail staining severely inhibited
sperm motility after 5 hr of incubation with sperm, although no agglu
tination was present. This immobilizing activity of MAbs would prevent
spermatozoa from reaching the oocyte in vivo.