Mucous membrane pemphigoid is an autoimmune reaction that occurs at the level of the basement membrane. Normally infects gingiva. Desquamating/blistering disease where epithelial separation takes place at a level of the basement membrane.

Antibodies (IgG) precipitates complement (C3) in the lamina lucida of the BM. Circulating auto-antibodies to BP-One antigen (located in hemidesmosome). 50% use BP-Two. Caring Nikolsky sign. IgG, C3 deposition at BM creating smooth line inside immunoflourescent analysis.