Specificity and inhibition of the epidermal cell detachment induced by pemphigus IgG in vitro

IgG isolated from sera of patients with pemphigus vulgaris (PV) has been shown to induce cell detachment when added to primary epidermal cell cultures (PECC). We studied the specificity of this phenomenon. IgG fractions were purified from the sera of five patients with PV and control IgG fractions from the sera of normal donors and patients with bullous pemphigoid (BP), systemic lupus erythematosus (SLE), and anti-AB blood group sera (anti-AB). IgG fractions were added to PECC either at initial plating (0 hours), at media change (48 hours), or sequentially at both times, and cell detachment was quantitated at 72 and 96 hours. Significant cell detachment occurred only when PV IgG was added to the growth media sequentially at 0 and 48 hours (p = 0.001), and this effect was dose-dependent for either dose. Substitution of an unrelated IgG (BP, SLE, or anti-AB) at either time points reduced cell detachment to near control values. Furthermore, cell detachment was inhibited by the addition of the proteinase inhibitors α₂ macroglobulin (70% inhibition of detachment), aprotinin (63% inhibition), soybean and lima bean trypsin inhibitor (62 and 64%, respectively), and pepstatin (49%), but not by the inhibitors chymostatin, leupeptin, or antipain. These data confirm that PV IgG induces increased cell detachment in PECC and shows that this effect is specific for PV IgG, is dose-dependent, and may be inhibited by certain proteinase inhibitors.