Intravenous immunoglobulin (IVIg)–a relatively new approach to treat pemphigus–lowers serum levels of pemphigus antibodies; however, the optimal way to use this agent is unknown.

We sought to examine whether coadministration of a cytotoxic drug to patients with pemphigus improves the ability of IVIg to decrease serum levels of intercellular (IC) antibodies.

In this retrospective study, we analyzed changes in IC antibody levels in 20 patients with pemphigus who were treated with 24 courses of IVIg administered alone (n = 10) or with a cytotoxic drug (n = 14). Each course of IVIg consisted of 400 mg/kg daily of immunoglobulin given over 5 days every other week; this cycle was repeated 3 to 4 times. Serum levels of IC antibodies were measured at baseline, before treatment, and 1 week and 1 month after the last IVIg cycle.

One week after the last IVIg cycle IC antibodies decreased by an average of 77% in the group treated with IVIg and cytotoxic drug compared with 48% in the group treated with IVIg alone (P = .54), and by 90% versus 43% 1 month later (P = .03).

A larger sample size is suggested for future studies.

These observations confirm that IVIg can rapidly lower serum levels of autoantibodies in patients with pemphigus and its ability to do so is improved by the coadministration of a cytotoxic drug. These findings imply that the clinical effectiveness of IVIg in treating pemphigus, and possibly other autoantibody-mediated diseases, may be improved by the concurrent administration of a cytotoxic drug.