The effect of rituximab therapy on immunoglobulin levels in patients with multisystem autoimmune disease

Rituximab is a B cell depleting anti-CD20 monoclonal antibody. CD20 is not expressed on mature plasma cells and accordingly rituximab does not have immediate effects on immunoglobulin levels. However, after rituximab some patients develop hypogammaglobulinaemia. We performed a single centre retrospective review of 177 patients with multisystem autoimmune disease receiving rituximab between 2002 and 2010. The incidence, severity and complications of hypogammaglobulinaemia were investigated. Median rituximab dose was 6 g (1-20.2) and total follow-up was 8012 patient-months. At first rituximab, the proportion of patients with IgG