The origin of immunoglobulins in semen.
IgG and IgA, albumin and lactoferrin as well as the semen compartment parameters acid phosphatase, fructose and spermatozoa were determined in separately collected fractions of the same ejaculate of some normal donors. The distribution over the fractions per ejaculate of IgG, IgA and albumin was generally more or less similar to the distribution of acid phosphatase indicating that the bulk of these proteins enters the semen via the prostate and not via the vesicles or testis and epididymis. The distribution of lactoferrin unexpectedly was not clearly related to fructose. IgM could not be detected. 
 
The concentrations in the (eight) total ejaculates expressed as percentages of the serum concentrations were for albumin slightly higher than for IgG, both in the order of 1% and moreover correlated with each other, indicating that IgG reached the seminal fluid in general by transudation from the circulation. The relative IgA concentrations could not be measured exactly but seemed to be slightly higher than of albumin, and not correlated to albumin concentrations, suggesting that local production of IgA may occur also.