Secretory Piece linked to IgM in Individuals deficient in IgA

Abstract

THE IgA in exocrine secretions, by contrast with that in serum, is an 11S dimer containing an additional antigenic fragment, variously referred to as the transport piece, secretory piece or simply as the “piece” (ref. 1). Piece determinants, as detected by double diffusion precipitation in agar with a specific antiserum, occur in small amounts in the sera of up to 40 per cent of individuals with untreated adult coeliac disease, and in 9 per cent of healthy persons². During a search for piece determinants I have examined the sera of thirty-four patients deficient in IgA. Thirty had hypogammaglobulinaemia or dysgammaglobulinaemia and had an increased susceptibility to infections. Four had other symptoms, but no history of repeated infections.