Use of sodium-chloride separated human skin in detection of circulating anti-basement membrane zone antibodies

Abstract

The sensitivity of the indirect immunofluorescence (IIF) technique for detection of circulating basement membrane zone (BMZ) antibodies was evaluated, employing NaCl-separated human skin and intact skin as substrate. Consecutive serum samples from 12 patients with clinically, histologically and immunohistologically verified bullous pemphigoid (BP) were investigated in parallel on both substrates, in dilutions ranging from 1:10 to 1:1,280. All BP sera showed linear deposits of IgG at the BMZ on intact skin, with titres ranging from 10 to 160. On NaCl-separated skin, all BP sera produced a linear epidermal fluorescent band for IgG, with titres ranging from 80 to 1,280. None of the sera showed deposits of IgM anti-BMZ antibodies. Sera from 5 healthy donors (dilutions 1:10) produced no fluorescence, either on intact or on NaCl-separated skin. The serum-titres of circulating anti-BMZ IgG antibodies in 2 patients with corticosteroid-resistant BP were significantly reduced (from 160 to less than 10) during treatment with plasmapheresis, when using NaCl-separated skin as substrate for IIF, whereas the serum-titres showed insignificant reduction (from 20 to less than 10), when using intact skin as substrate. We conclude that the IIF method is more sensitive for detection of circulating anti-BMZ antibodies, when NaCl-separated skin as compared with intact human skin is employed as substrate.