Enzyme immunoassay for secretory immunoglobulin A on skin surface and in sweat

Recently secretory IgA (S-IgA) was found to be secreted from the eccrine gland. By using a sandwich enzyme immunoassay, we measured the concentration of S-IgA 1) in sweat (sweat S-IgA) and 2) in the extract buffer obtained by pipetting++ on the skin (skin surface S-IgA). Skin surface hydration and skin surface lipid were measured at the sites where the samples of skin surface S-IgA were collected. (These measurements were taken immediately after the buffer was pipetted). The quantity of both sweat S-IgA and skin surface S-IgA differed according to the sites where they were collected. Sites in order of decreasing sweat S-IgA level: face, chest, forearm. Sites in order of decreasing skin surface S-IgA level: face, chest, palm, forearm, sole. (Skin surface S-IgA levels on palm and forearm were approximately equal). Although the amount of skin surface S-IgA was not related to the skin surface hydration, there was a significant correlation between skin surface S-IgA and skin surface lipid.