Suppression of normal immune responses after treatment with rituximab.

PURPOSE OF REVIEW: Because rituximab is increasingly used in systemic autoimmune diseases, alone or in combination with other immunosuppressive medication, secondary reduction of normal immune defenses has become a more significant clinical problem.

RECENT FINDINGS: The goal of rituximab treatment of immune-mediated conditions is complete depletion of circulating B cells. Studies have suggested that lack of complete B-cell depletion is associated with nonresponse, and B-cell repletion can predict relapse. The resulting prolonged B-cell depletion is associated with risk of adverse effects including hypogammaglobulinemia, increased risk of infection, failure to develop immune responses after vaccination, and neutropenia. Pre-existing hypogammaglobulinemia has been linked to increased risk of reduction of IgG levels and serious infections after rituximab therapy, and concomitant cyclophosphamide therapy has been associated with an increased risk of developing hypogammaglobulinemia.

SUMMARY: Although rituximab therapy is effective in the treatment of many systemic autoimmune diseases and has an acceptable safety profile, treating physicians need to keep in mind that pre-existing hypogammaglobulinemia and likely also use of additional immunosuppressive agents can increase the risk of prolonged hypogammaglobulinemia and infection. In keeping with current recommendations for rheumatoid arthritis, we recommend that all patients who undergo rituximab therapy have baseline IgG, IgM, and IgA measurements and also have immunoglobulin levels monitored periodically during treatment.