473 A comparative study of bullous pemphigoid-180 and 230 antibodies in serum and blister fluid samples

Abstract

The diagnosis of bullous pemphigoid (BP) relies on the detection of tissue bound or circulating in patients’ sera IgG anti-basement membrane (BMZ) autoantibodies. Despite the reported comparable titers of anti-BMZ antibodies in both serum and blister fluid of BP patients using indirect immunofluorescence on salt-split skin substrate, only scarce data exist on the detection of antibodies to the BP antigens, BP180 and BP230, using the more sensitive and specific ELISA assays. In the present study, BP180NC16A and BP230 ELISA kits were used to compare the levels of the corresponding autoantibodies in pairs serum-blister fluid collected simultaneously in 38 newly diagnosed untreated BP patients. Our aim was to investigate whether blister fluid can be an alternative to sera for detecting anti-BP180 and anti-BP230 in the routine diagnosis of BP. Positive results for anti-BP180 antibodies (cut-off 20 RU/ml) were detected in 32 and 30 sera and blister fluid samples, respectively (n = 38, Cohen’s k = 0.826) which represents a very good correlation of the results. Similarly, anti-BP230 antibodies were positive (cut-off 20 RU/ml) in the serum and blister fluid of 13 and 12 patients, respectively (n = 38, Cohen’s k = 0.821). In addition, in 17 out of 38 patients (44.7%) there was full agreement between the ELISA BP180 and BP230 results in the serum-blister fluid pairs, all positive in 12 or all negative in 5 patients, respectively. In the remaining 21 patients the blister fluid tested positive only for anti-BP180 known to be of major pathogenic importance in BP. Only 3 out of 38 blister fluid samples showed negative results for both autoantibodies, whereas the corresponding serum samples were positive either for BP180 or BP230 antibodies. Our results demonstrate a relatively high agreement between the anti-BP180 and anti-BP230 values in the pairs serum-blister fluid, the latter being less invasive and easier to obtain in the routine diagnosis of BP, especially in elderly patients or children.