CIRCULATING PEMPHIGUS IGG IN FAMILIES OF PATIENTS WITH PEMPHIGUS - COMPARISON OF INDIRECT IMMUNOFLUORESCENCE, DIRECT IMMUNOFLUORESCENCE, AND IMMUNOBLOTTING

Background: Patients with pemphigus vulgaris (PV) are genetically link ed to two alleles of the HLA subgroup, and circulating antibodies were found in first-degree relatives of these patients, thus showing genet ic predisposition. Objective: Our purpose was to determine the occurre nce of circulating true PV-IgG in patients' relatives. Methods: Circul ating PV-IgG was determined in 21 first-degree relatives of 12 patient s with PV by indirect immunofluorescence on monkey esophagus, carcinom a A431 cultures, and Western immunoblotting. Direct immunofluorescence was performed on skin biopsy specimens of 20 relatives. Results: Circ ulating PV-IgG was detected in 15 relatives (71%) by all methods teste d. Good correlation was found between immunoblot reactivity and immuno fluorescence, Of the 15 ''positive'' relatives, only five showed fixat ion of IgG to epidermal cells in vivo. Conclusion: The permeability of the epidermis or epidermal cell reactivity in vivo probably controls the expression of disease in patients' relatives.