Immunoglobulin G replacement for the treatment of infective complications of rituximab-associated hypogammaglobulinemia in autoimmune disease : a case series

The anti-CD20 B cell depleting monoclonal antibody rituximab is being used increasingly for autoimmune diseases, including patients with refractory disease with extensive prior exposure to immunosuppressive treatments. Rituximab, in this context, may be associated with increased risk of adverse effects, in particular hypogammaglobulinemia which predisposes to recurrent infections necessitating Immunoglobulin G replacement. Outcome data following Immunoglobulin G replacement after rituximab in patients with autoimmune disease are limited. We conducted a retrospective study in a tertiary referral lupus and vasculitis clinic of 288 patients who received rituximab. Clinical details of patients prescribed IgG replacement therapy following rituximab treatment were reviewed. We identified 12 patients with autoimmune disease, 10/12 with systemic vasculitis, received IgG replacement for the treatment of recurrent infections in the context of persistent moderate or severe hypogammaglobulinemia following rituximab. We observed a range of ages (16-67 years), rituximab dosages (2-15.8 g), previous immunosuppression (median 3.5 non-glucocorticoid agents) and duration of disease (2-228 months). Six continued to receive rituximab alongside IgG replacement therapy to maintain disease control. IgG replacement appeared to decrease the incidence and severity of infections, and recovery of IgG concentrations allowed cessation of IgG replacement in two patients after 4 and 7.5 years of treatment. IgG monitoring is useful for patients receiving rituximab. IgG replacement for sustained hypogammaglobulinemia with recurrent infections appeared to be useful in this series. The IgG replacement course is prolonged in most patients, but IgG recovery is reported.