Development of Serum Sickness-Like Symptoms After Rituximab Infusion in Two Patients With Severe Hypergammaglobulinemia

In Brief Rituximab is a monoclonal antibody that depletes B cells and is commonly used for the treatment of autoimmune diseases. In this report, we describe 2 patients with autoimmune diseases and marked hypergammaglobulinemia attending at a tertiary care hospital, who, following treatment with rituximab, developed a severe serum-sickness-like reactions. Both patients were treated with intravenous corticosteroids, recovered well, and on follow-up, were negative for the development of human antichimeric antibodies. Based on these and other similar cases in the literature, we propose that severe hypergammaglobulinemia due to autoimmune conditions may be a predisposing factor for the development of a serum sickness-like reaction after treatment with Rituximab, which can sometimes occur without prior exposure to this antibody. Rheumatologists should be aware of this possible association when prescribing this medication. One patient's reaction occurred after the first infusion. The authors speculate that increased IgG may predispose to serum sickness-like reactions.