Abstract

A spontaneously occurring antibasement membrane antibody has been further characterised according to antigenic specificity, immunoglobulin class, and tissue localisation using immunofluorescent and immunoelectron microscopic techniques. The autoantibody reacted with the basement membrane of kidney tubules, Bowman's capsule, and the epithelial portion of ileum but not with the basement membrane of skin, cornea, glomerulus, or oesophagus. It also reacted with bile canaliculi, sarcolemmal sheath, and salivary duct. On electron microscopy the antibody was distributed along the basement membrane of Bowman's capsule and renal tubules. Some reactivity against collagen was observed. Antibody activity was found in both IgG and IgM fractions. In immunodeficiency disorders, the autoantibody was found only in patients with selective IgA deficiency.