Fig. 10. Antibody-induced aggregation of sperm plasma membrane GSTs. Capacitated sperm were exposed to anti-GST antibodies and fixed at different time points in 4% buffered formaldehyde and immunostained using anti-GST Pi antibodies. (A) 0 minutes, (B) 15 minutes, (C) 30 minutes and (D) 60 minutes incubation of live spermatozoa with anti GST PiN antibodies (1:25) at 37°C. (E) The effect of antibody crosslinking of sperm plasma membrane GSTs on acrosin release. Acrosin release was measured after aggregation of GSTs on capacitated spermatozoa and was induced by anti-GST PiN antibodies. The bar shows mu/minute of acrosin released/10⁶ sperm. Capacitated sperm were treated with (a) preimmune serum (1:25), (b) SZP (10 µg/ml), (c) anti-GST-Pi (1:10), (d) anti-GST-Pi (1:25), (e) anti-GST-Pi (1:50), (f) anti-GST-Pi (1:50) + antirabbit IgG (1:100), (g) anti-GSTMu (1:10), (h), Anti-GSTMu (1:25), (i) anti-GSTMu (1:50), and (j) anti-GSTMu (1:50) + antirabbit IgG (1:100). Anti-rabbit IgG (1:50) did not have any effect on acrosin release (data not shown). a versus b,c,f,g,j; e versus f; i versus j: P<0.0001. a versus d: P<0.005. Bar, 20 µm.