[Rituximab and hypogammaglobulinemia]

Rituximab, a chimeric monoclonal antibody against CD20, induces the depletion of B lymphocytes. It is used for the treatment of lymphoproliferative and autoimmune diseases. Antibody immunodeficiency associated to RTX treatment is a new motif for consultation to our service. We decided to study those patients that having been treated with RTX, consulted for hypogammaglobulinemia or recurrent infections between November 2010 and December 2014. We evaluated eight patients, seven female and one male. The average follow up time was 19.3±18.8 months, range 1 to 54, median 13. Three had a normal electrophoretic proteinogram before receiving RTX, three had hypogammaglobulinemia and in two data was not available. None of them had a quantitative determination of immunoglobulins before receiving RTX. Four received RTX as a treatment of non Hodking lymphoma, two as a treatment of chronic lymphocytic leukemia, one for immune thrombocytopenic purpura and other for microscopic polyangiitis. Six were diagnosed with hypogammaglobulinemia and one with combined IgM, IgA and IgG2 deficiency. Five presented infections, four of them with good response to intravenous immunoglobulin. RTX related antibody deficiency consultations are increasing. It is important to determine the immunoglobulin levels previously to RTX use in order to establish an etiologic relationship with RTX and a quick diagnosis of antibody deficiency. The substitutive treatment with gammaglobulin seems to be useful in patients with severe or recurrent infections.