Leukocyte chemotaxis to the dermal-epidermal junction of human skin mediated by pemphigoid antibody and complement: Mechanism of cell attachment in the in vitro leukocyte attachment method

Abstract

In a previous study a functional interaction between pemphigoid antibodies, pemphigoid antigen, serum complement, and leukocytes was shown using the leukocyte attachment method for detecting immune complexes in skin. In the method, leukocytes suspended in fresh serum attached in a specific linear pattern to the dermal-epidermal junction of skin sections pretreated with pemphigoid sera containing complement-binding anti-basement membrane zone antibodies. In this study, the mechanism of the attachment reaction has been investigated using a modification of the method as a visual assay of leukocyte migration on skin. Using the visual assay it was shown that leukocyte attachment is dependent on directed migration of cells to the dermal-epidermal junction. Chemotaxis mediated by pemphigoid antibodies and fresh serum was confirmed by continuous observation, analysis of time-sequence photomicrographs of cell migration and cinematography. A requirement for leukocyte migration in the standard leukocyte attachment assay was supported by showing that attachment could be inhibited by leukocyte 'deactivation' and by treatment of cells with the inhibitors of migration, cytochalasin B and colchicine. Using decomplemented sera, C2-deficient serum and skin-antibody-complement intermediates, leukocyte chemotaxis and attachment to the junction was shown to require complement and functional evidence for activation via the classical pathway and a role for C5 demonstrated. These studies show that leukocyte attachment is dependent on chemotaxis and that pemphigoid antibody-mediated complement activation can support one (chemotaxis) and probably 2 (immune adherence) inflammatory cell functions. Furthermore, they provide additional functional evidence that pemphigoid antibodies may be important in the pathogenesis of cutaneous inflammation in bullous pemphigoid.