Bullous pemphigoid IgG2 and IgG4 antibodies have a capability to inhibit a transient increase of intracellular Ca2+ induced by bullous pemphigoid IgG1 antibody.

To elucidate the role of Bullous pemphigoid (BP) IgG subclasses in the transmembrane signal transduction of keratinocytes, we examined whether BP IgG2 or IgG4 inhibits the intracellular Ca2+ concentration ([Ca2+]i) increase induced by BP IgG1. IgG2 from one of five BP patients inhibited the increase of [Ca2+]i in human squamous cell carcinoma cell line; DJM-1 cells induced by BP IgG1. IgG4 from two of four BP patients inhibited the increase of [Ca2+]i induced by BP IgG1. In addition, a two fold quantity of IgG2 inhibited the increase of [Ca2+]i induced by BP IgG1. A two fold quantity of IgG4 from two of five BP patients inhibited the increase of [Ca2+]i induced by BP IgG1. These results indicate that BP IgG2 and IgG4 have a capability to inhibit the increase of [Ca2+]i induced by BP IgG1.