Enzyme-linked immunosorbent assay for the combination of bullous pemphigoid antigens 1 and 2 in the diagnosis of bullous pemphigoid.

OBJECTIVE To assess the usefulness of enzyme-linked immunosorbent assay (ELISA) assessment of the combination of bullous pemphigoid antigen 1 (BPAG1) and BPAG2 in the diagnosis of bullous pemphigoid (BP). DESIGN Retrospective study of serum samples from patients with BP. SETTING Tertiary care center. PATIENTS A total of 190 patients with newly diagnosed BP and 78 controls with other autoimmune bullous diseases. INTERVENTION Serum samples were tested using commercialized BPAG1 and BPAG2 ELISA and indirect immunofluorescence (IIF). MAIN OUTCOME MEASURES The sensitivity and specificity of ELISA for the combination of BPAG1 and BPAG2 in the diagnosis of BP were contrasted with ELISA for each of the antigens alone and with IIF. RESULTS The sensitivity and specificity of ELISA for the combination of BPAG1 and BPAG2 were 87% and 88%, respectively, compared with 79% and 90% for BPAG2 ELISA, 61% and 96% for BPAG1 ELISA, and 81% and 63% for IIF. The combination of BPAG1 ELISA and BPAG2 ELISA permitted 8% and 16% gains in sensitivity compared with each of BPAG2 ELISA and BPAG1 ELISA alone, respectively. Anti-BPAG1 antibodies were detected in 15 of 40 BP serum samples with no anti-BPAG2 antibodies (38%) and in 8 of 13 serum samples from patients with BP and mucosal involvement (62%) compared with 2 of 22 samples of cicatricial pemphigoid (P = .002) and 0 of 16 epidermolysis bullosa acquisita serum samples (P < .001). The BPAG2 ELISA values were more closely correlated with initial extent of BP lesions (r = 0.44, P < .001) than BPAG1 ELISA values (r = 0.16, P = .03). CONCLUSION Since the combination of BPAG1 and BPAG2 ELISA only slightly increases the sensitivity of BP diagnosis over BPAG2 ELISA alone, BPAG1 ELISA could be adequately proposed in a minority of BP cases with mucosal involvement and in those with no circulating anti-BPAG2 antibodies.