The immunohistology of glomerular antigens. V. The collagenous antigens of the glomerulus.

Distinct antigenic loci are present within the human glomerulus as demonstrated by high resolution epifluorescent and phase-contrast microscopic techniques using affinity-purified antibody to characterized collagens. Type IV mouse tumor procollagen and type V collagen are present within the mesangium and along the endothelial aspect of the glomerular basement membrane, demonstrating antigenic continuity between these two glomerular zones. In contrast, antiserum to type IV collagen from bovine lens capsule reacts with the full thickness of the glomerular basement membrane, as well as in the tubular basement membrane and Bowman's capsule. Types I procollagen and collagen are found within the epithelium; and types III collagen and procollagen are not detected within the glomerulus. The functional role of the multiple distinct "basement membrane" collagens in the glomerular capillary wall is unknown. A complex structure is suggested, especially in the mesangial-subendothelial continuity, and in the differential localization of two forms of type IV collagen within the glomerular basement membrane.