IGA ANTIBODIES IN CHRONIC BULLOUS DISEASE OF CHILDHOOD REACT WITH A 97-KDA BASEMENT-MEMBRANE ZONE PROTEIN

Chronic bullous disease of childhood (CBDC) is an autoimmune blisterin g disease occurring in prepubertal children, Both CBDC and its adult c ounterpart, linear IgA bullous dermatosis (LABD), are characterized by linear deposition of IgA along the cutaneous basement membrane zone ( BMZ), Circulating IgA antibody in LABD has been found to bind to a 97- kDa BMZ antigen, whereas the antigen in CBDC has not been well charact erized, The purpose of this study was to evaluate the immunoreactivity of BMZ IgA antibodies in a series of CBDC patients, We evaluated 12 s era from patients with CBDC with circulating IgA anti-BMZ antibodies o n indirect immunofluorescence (IIF), which stained the epidermal side of split skin with titers ranging from 1:20 to 1:640. Immunoblotting w as performed against two preparations of BMZ proteins: one enriched wi th the two bullous pemphigoid antigens (BP230, BP180) and one enriched with the LABD antigen (LABD97). Eight of the twelve sera reacted with a 97-kDa protein that co-migrated with the protein detected in many L ABD sera, The intensity of the reaction on immunoblot correlated with serum antibody titers, There was no consistent pattern of reactivity o f the IgA anti-BMZ antibodies with either the BP230 or BP180 antigens, although two sera reacted with several higher molecular mass proteins (160-200 kDa), The significance of this reactivity was examined with immunoblotting using BMZ-affinity-purified antibodies, and BF using ni trocellulose-eluted antibodies. One serum also contained anti-BMZ IgA antibodies that reacted with a 180-kDa protein, corresponding to BP180 . We conclude that IgA antibodies in CBDC sera recognize a 97-kDa BMZ antigen present on the epidermal side of BMZ split skin that co-migrat es with the antigen previously identified in LABD. These findings sugg est that CBDC and LABD are the immunologically related disorders occur ring in different age groups.