Anti-laminin 332 (lam332) mucous membrane pemphigoid (MMP) is a pemphigoid disease (PD) characterized by predominant mucosal involvement and autoantibodies against lam332. In nearly 30% of patients, the disease is associated with solid malignancies. For this reason, a reliable and sensitive detection of anti-lam332 antibodies is essential. This study compared the performance of 2 novel diagnostic indirect immunofluorescence (iIF) tests, which have been independently developed in our laboratories. One assay is based on recombinant lam332 expressed in HEK239 cells (biochip assay) and the other (keratinocyte footprint assay) on the migration trails left on glass coverslips by cultured keratinocytes which are rich in lam332 but contain no other PD autoantigens. In both tests, substrates were incubated with patient sera and bound IgG was detected by IF dye-conjugated secondary antibodies. 53 anti-lam332 MMP sera, 35 other MMP sera (iIF negative or reactivity with other autoantigens than lam332), 30 pemphigus vulgaris (PV) sera, and 20 sera of healthy blood donors (HBD) were analyzed. The included anti-lam332 MMP sera had been diagnosed by iIF on salt-split skin, immunoblotting, immunoprecipitation, and iIF on lam332-deficient skin. In both assays, while no reactivity was seen in any of the 50 PV and HBD sera, 51 and all anti-lam332 MMP sera were positive in the biochip and the footprint assay, respectively. In the other 35 MMP sera, 5 positives were found in both tests and 4 more showed week reactivity in the footprint assay. Thus, both tests systems show a high concordance between and as such validate each other. In conclusion, both assays are easy to perform, sensitive, highly specific and will further facilitate the diagnosis of anti-lam332 MMP.

Comparison of two tools for the serological diagnosis of anti-laminin 332 mucous membrane pemphigoid