Journal of Cutaneous Pathology 1979: 6: 91-95 Immunohistochemical Demonstration of Basement Membrane Collagen in Normal Human Skin and in Psoriasis S. GAY, T. F. KRESINA, R. GAY, E. J. MILLER AND L. F. MONTHS Departments of Medicitie, Biochemistry, Dermatology and Institute of Dental Research, University of Alabama, Birmingham, Alabama, U.S.A. Antibodies prepared against the collagen C-chain derived from hutnan placenta specifically stain the epidcntial basetnent membrane of normal human skin as well as the basetnent metnbrajie surrounding the skin appendages and capillaries. Using the antibodies, it was observed that all basetnent tncmbranes in untreated psoriatic plaques appear fragtnented and separated into several layers. The results suggest that psoriatic lesions are associated with a general loss of basement membrane integrity which may play a crucial role in the pathogenesis of the disease. (Reeeived for pubiieation Oetober 2, 1978) In recent years, several investigations have shown that vertebrate organisms are endowed with genetically and chetnically distinct types of collagen (Miller 1976), Fibers or fibrils derived from Type I, Type I-Trimer, Type II, and Type III molecules represent the interstitial collagens. These collagens form the essential structural elements of a variety of connective tissues (Gay & Miller 1978). Fibers derived from Type I, Type I- Trimer and Type III molecules occur within the dermal layer of skin and are responsible for the functional integrity of this organ. In addition to the interstitial collagens, several lines of evidence indicate the presence of still further fortns of collagen in the structures commonly recognized as basement membranes. To date, these collagens have often been designated as Type IV collagen (Miller 1976), Neverthe- less, it is becoming increasingly clear that basement membrane collagen is comprised of several different types of molecules. Thus, the A- and B-chain collagens (Rhodes & Miller 1978) appear to originate from certain basement membranes which are prominent in placental tissue (Burgenson et al, 1976), Moreover, recent investigations have resulted in the isolation and charac- terization of two additional collagen chains derived frotn basement membranes. These have been designated as the C- and D-chains which have been isolated from placental tissue (Kresina & MiUer, manuscript sub- mitted) as well as from lens capsule (Gay & Miller tnanuscript in preparation). The biochemical characterization of the different basement tnetnbrane collagen chain has allowed concomitant immuno- histological investigations on these com- ponents in normal and pathological tissues. In the present study we report on the use of specific anitbodies directed against the human C-chain to itivestigate the disposition of skin basement membranes in nortnal human skin as well as in psoriatic lesions. Material and Methods The collagen C-chain was isolated and purified from limited pepsin digests of human placenta as described by Kresina & Miller (manuscript subtrtitted) and used for imtnunization of rabbits. For each rabbit, 5 trtg of antigen were dissolved in l,5tTtl of 0,05% acetic acid, emulsified in 1.5 ml of complete Freund's adjuvant (Difco Lab.) 0303-6987/79/020091-05 .$02.50/0 © 1979 Munksgaard, Copenhagen