In this study, we present data on patients with pemphigus vulgaris (PV), pemphigus foliaceus (PF), bullous pemphigoid (BP), mucous membrane pemphigoid (MMP), and ocular cicatricial pemphigoid (OCP), who had decreased levels of serum IgM, during their systemic therapy. The gene discussed is CD40LG; the disease is ocular cicatricial pemphigoid.