Hypogammaglobulinemia after rituximab for rheumatoid arthritis is not rare and is related with good response: 13 years real-life experience.

HGG occurred in 43% of RTX-treated patients. Patients who developed low IgG or low IgM had lower baseline levels than those who did not. Concomitant DMARD and corticosteroid therapy was not associated with HGG. Low IgM, but not low IgG, development was associated with better disease outcomes. HGG was not associated with an increased incidence of serious infections.