Experimental studies on the passage of specific IgG to the lumen of the rabbit epididymis.

The extent to which specific IgG can reach the lumen of the rabbit cauda epididymidis was investigated by comparison of the concentration in serum and fluid of the cauda epididymidis of a specific IgG raised against dinitrophenylated bovine gamma globulin (DNP--BGG). This specific IgG reached the epididymal lumen although in much lower concentration than the levels in serum. The IgG was measured by a specific sensitive radioimmunoassay and in 13 normal males there was a mean molar ratio of 4.0 x 10(-3) (range: 2.5--11.0 x 10(-3)) between the epididymal lumen and blood: the mean ratio between cerebrospinal fluid and blood was 1.7 x 10(-3) (4 males). Calculations, based on the absolute concentration of anti-DNP IgG in epididymal fluid in relation to total number of spermatozoa and estimated fluid volume in the cauda epididymidis, indicated approximately 40 000 molecules anti-DNP-BGG IgG per spermatozoon. This ratio was not affected 6 days after castration or 3--4 months after vasectomy, but it was about 10 times higher than that of the controls in the cryptic epididymis subjected for 6 days to body temperature.