LABD97 IgG ELISA increases sensitivity of ELISA serologic testing for the diagnosis of bullous pemphigoid.

BACKGROUND

Commercially available, antigen-specific serologic testing for bullous pemphigoid (BP) fails to identify approximately 1 in 4 patients with circulating IgG autoantibodies to the epidermal side of human split skin substrate by indirect immunofluorescence (IIF).

OBJECTIVE

Determine the utility of LABD97, a proteolyzed fragment of the shed ectodomain of BP180, as an antigenic target in an IgG ELISA assay to confirm BP diagnosis.

METHODS

Retrospective study of 100 consecutive serum specimens submitted to the Immunodermatology Laboratory at the University of Utah for suspected (initial diagnosis) BP with epidermal pattern IgG/IgG4 on human split skin substrate by IIF.

RESULTS

Within 100 consecutive BP sera, LABD97 IgG ELISA was the most sensitive antigenic target (87%) compared to the commercial-BP180 (NC16A) IgG ELISA (66%) and BP230 IgG ELISA (52%). Additionally, 83% of BP patients that were double negative for commercially available NC16A/BP230 ELISAs were LABD97 positive.

LIMITATIONS: Single-center study, limited clinical data and patient follow up.

CONCLUSION

LABD97 is a more complete and diagnostically relevant portion of BP180 compared to the NC16A BP180 fragment. Utilizing LABD97 ELISA testing significantly increases the sensitivity of serologic BP diagnosis.