CD40LG and mucous membrane pemphigoid: OCP is a subset of systemic autoimmune disease mucous membrane pemphigoid, which extensively involve mucosal surfaces, such as the oral cavity, larynx, pharynx, esophagus, eye, nasal cavity, and genitalia.[1,3] Classically, mucous membrane pemphigoid is characterized by a type II immune reaction depending on specific deposition of immunoreactants (IgG, IgA, IgM, and/or complement) along the epithelial basement membrane.[1,3,5,6] This type II reaction leads to activation of the complement cascade provoking an intense inflammation.