Identification of Human Seminal Plasma Components that Bind I_g G₂ Variant

Abstract

Human seminal plasma (hsp) contains soluble proteins capable of binding immunogfobulin (Ig) G. Two novel components with estimated molecular sizes of 90 and 21 kD interact specifically with a variant of IgG2 found in 20% of human sera tested. The common IgG₂ present in human sera and other subclasses of IgG did not bind with the hsp components. The present finding shows that the interacting IgG₂ is a variant and not the common or prevalent species. The 90-kD component of hsp with IgG₂ binding property is probably a nonglycosylated protein, whereas the 21-kD component is a glycosylated protein. The 90- and 21-kD components were detected in 20% of hsp specimens tested. Thus they are not present in the majority of hsp. Since the IgG₂ binding components of hsp and the serum IgG₂ variant are found in 20% of men and 20% of individuals, respectively, they can be used as genetic markers.

Key Words:

• seminal plasma
• immunoglobulin
• immunosuppressive factor
• IgG
• protein
• genetic marker