Monoclonal antibodies to native basement membranes reveal heterogeneous immunoreactivity patterns

In this paper we describe the development of basement membrane (BM) reactive monoclonal antibodies (MA), by immunization of mice with intact denuded BM. The MA raised against denuded amniotic BM (clones 1052, 1053 and 1065) showed heterogeneous staining patterns. MA 1052 and 1053 reacted with epithelial BM of the epidermis and epidermal adnexa and furthermore with the epithelial alveolar BM in the lung and the superficial part of the epithelial BM in the gastrointestinal tract. MA 1065 showed immunoreactivity with the epithelial BM of epidermis and epidermal adnexa and the epithelial BM of trachea and oesophagus, and furthermore pericellular staining of the basal keratinocytes and basal corneal epithelial cells. MA 1087, raised against human glomerular BM, showed immunoreactivity with all BM, except the central epithelial BM in the cornea. The precise localization of the target epitopes in the BM was investigated on chemically cleaved human skin. Reactivity for the MA occurred predominantly in the BM lamina adherent to the dermis, suggesting that the target epitopes reside in the lamina densa and/or lamina fibroreticularis. We furthermore examined the nature of the epitopes by preincubation of tissue sections with various enzymes prior to immunohistochemistry. The reactivity of the target epitopes was not affected by bacterial collagenase, but after various protease treatments the reactivity disappeared, suggesting that the epitopes are not localized on the triple helical part of collagenous proteins.