Anti-beta-endorphin immunoglobulin G in humans.

Human IgG specific for beta-endorphin was identified by enzyme-linked immunoabsorbent assay and isolated by affinity chromatography. From a sample of 27 subjects, three individuals with major depression demonstrated plasma IgG highly reactive with human beta-endorphin, while four other subjects (two with depression and two randomly selected blood donors) had intermediate reactivity. The recognition site for beta-endorphin was retained by F(ab')2 fragments.