The use of two substrates for indirect immunofluorescence in the diagnosis of pemphigus: reply from authors.

Abstract

Sir, We thank Jarząbek‐Chorzelska et al. for the interest shown in our paper.1 They concur that two substrates should be used for indirect immunofluorescence (IIF) in order to detect antibodies to both desmoglein (Dsg) 1 and Dsg3 in pemphigus sera. We read with interest that the use of human oesophagus (HO) and guinea‐pig oesophagus (GPO) has proved to be the most sensitive combination of substrates in their experience over many years. In our study, we used a combination of monkey oesophagus (MO) and human skin (HS). The aim of our study was to compare IIF titres on these two substrates in the knowledge not only of the pemphigus subtype, i.e. pemphigus vulgaris (PV) or pemphigus foliaceus (PF), but more specifically the serum content of Dsg1 and Dsg3 antibodies, which were quantitatively measured by enzyme‐linked immunosorbent assay (ELISA). We established that variation in relative titres on these two substrates could be explained by the content of Dsg1 and/or Dsg3 antibodies in sera. HS proved to be more sensitive for detection of Dsg1 antibodies, which are found in all PF sera and approximately 60% of PV sera.2 MO was better for the detection of Dsg3 antibodies which are characteristic of PV. Combining data from both substrates enhanced the overall sensitivity of IIF for PV and PF sera. In addition, the relative titres on each substrate helped differentiate PV and PF.