An antibody to BP 180 kDa antigen is able to induce an increase of intracellular Ca2+ concentration in DJM-1 (human squamous cell carcinoma) cells

To elucidate the induction of transmembrane signal transduction of keratinocytes by bullous pemphigoid (BP) antibodies, we assessed the intracellular Ca2+ concentration ([Ca2+]i) in DJM-1 cells (a squamous cell carcinoma cell line). The time course of fluo-3-fluorescence intensity was investigated, and transient increase of fluorescence intensity in DJM-1 cells was observed when the DJM-1 cells were incubated with rabbit IgG anti-human BP 180kDa antigen (BP 180). No increase of fluorescence intensity was observed when the cells were incubated with rabbit IgG anti-human BP 230 kDa antigen (BP 230). This transient increase of fluorescence intensity was inhibited by U-73122, a specific inhibitor of phospholipase C. These results indicate the possibility that an antibody to BP 180 induces transmembrane signal transduction in keratinocytes.