Antigens of immunoglobulin G-Fc receptor III in human male reproductive tract accessory glands.

We have documented the presence of soluble antigens of immunoglobulin (Ig)G-Fc receptor type III (FcRIII) in human seminal plasma that retain an affinity for the Fc fragment of IgG. The origin of these FcRIII antigens within the male reproductive tract was not known. By using polyclonal and monoclonal antibodies directed against different epitopes on FcRIII molecules, we demonstrated FcRIII reactivity in human prostate and seminal vesicle epithelial cells as well as in their glandular secretions. The FcRIII monoclonal antibody reactivity was removed by absorption with either seminal plasma or polymorphonuclear leukocytes that express FcRIII. Absorption of FcRIII monoclonal antibody with polymorphonuclear leukocytes also removed the reactivity with seminal plasma and vice versa. These data show for the first time that male accessory glands are a source of soluble FcRIII antigens.