A search for circulating immunoglobulins blocking follicle-stimulating hormone action in male idiopathic infertility

In this study, patients with idiopathic infertility were investigated for the presence of circulating antibodies which interfered with follicle-stimulating hormone (FSH) activity. A retrospective search for autoantibodies was undertaken using single plasma samples obtained from 29 infertile men with azoo/oligo/asthenoteratozoospermia and eight controls with normozoospermia and normal blood FSH levels. Plasma levels of immunoactive FSH, bioactive FSH, immunoactive luteinizing hormone and testosterone were measured in the individual samples. Plasma immunoglobulin G (IgG) was isolated using protein-A chromatography and tested at different dose levels for its ability to inhibit and/or stimulate basal and FSH-induced aromatase activity in immature rat Sertoli cells in vitro. In the first set of trials, IgGs isolated from three infertile patients showed apparent inhibition of FSH-stimulated aromatase activity, two showed further stimulation and five showed irregular fluctuations beyond the normal range of stimulation. When reanalysed at different doses, none of the IgG fractions exhibited abnormal interference with FSH action. It is concluded that, unlike many other endocrine disorders characterized by autoimmunity, the occurrence of autoantibodies of the IgG class blocking FSH action in male infertility is improbable.