- Design
- Retrospective diagnostic accuracy series, single laboratory
- Population
- 100 consecutive sera with suspected pemphigoid and epidermal-pattern IgG on split-skin immunofluorescence
- Primary outcome
- ELISA sensitivity by antigen target
- Effect
- LABD97 87% vs BP180 NC16A 66% vs BP230 52%; 83% of double-negatives LABD97 positive
A university immunodermatology laboratory tested 100 consecutive sera from patients with suspected bullous pemphigoid, all showing epidermal-side IgG on salt-split skin indirect immunofluorescence. Each was run on the commercial BP180 NC16A and BP230 ELISAs and on an ELISA against LABD97, a larger shed fragment of BP180.
Sensitivity was 66% for the commercial BP180 ELISA, 52% for BP230 and 87% for LABD97. Of sera negative on both commercial tests, 83% were LABD97 positive.
The key message holds whatever test you can get: about one in three patients with pemphigoid antibodies will have a negative standard BP180 ELISA. LABD97 testing is not routinely available in India, so a negative commercial result should prompt indirect immunofluorescence on salt-split skin or direct immunofluorescence of perilesional skin rather than reassurance. This is a single-centre retrospective series with limited clinical follow-up.
- Do not exclude bullous pemphigoid on a negative BP180 or BP230 ELISA alone.
- Send perilesional skin for direct immunofluorescence when pemphigoid is suspected.
- Request salt-split skin indirect immunofluorescence when ELISA is negative but suspicion remains.
- Consider pemphigoid in older patients with persistent itch even before blisters appear.
Why it matters
A false-negative ELISA can delay diagnosis in frail older patients for months.
Don't overread it
One retrospective single-centre series; LABD97 accuracy needs testing elsewhere.
The statistics, in plain English
Sensitivity is the proportion of true cases a test detects. These sera were selected because immunofluorescence was already positive, which tends to make all the ELISAs look somewhat better than they would in unselected patients.
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