Bullous pemphigoid of childhood: Autoantibodies target the same epitopes within the NC16A domain of BP180 as autoantibodies in bullous pemphigoid of adulthood

Background: Bullous pemphigoid (BP) is an autoimmune subepidermal blistering disease of the elderly that rarely occurs in children. Most adult BP serum samples react with epitopes within the NC16A domain of BP180, a glycoprotein of the cutaneous basement membrane zone. Objectives: To characterize the autoimmune response in childhood BP using recombinant forms of BP180 and to determine the subclass distribution of autoantibodies and their correlation with disease activity. Observations: Serum samples from 2 infants with BP, aged 4 and 5 months, reacted by immunoblot analysis with 4 epitopes clustered within the N-terminal 45 amino acids of the NC16A domain. The same 4 epitopes have previously been shown to be the target in adult BP. Childhood BP antibodies to BP180 NC16A belonged to IgGI, IgG2, IgG3, and IgG4 immunoglobulin subclasses. IgE reactivity was not detected. Serum levels of antibodies targeting BP180 NC16A paralleled disease activity as detected by enzyme-linked immunosorbent assay. Conclusions: The fine specificity of autoantibodies to BP180 is the same in BP of childhood and adulthood. Childhood BP is a true variant of BP.