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Rituximab, an antibody against CD20 on B lymphocytes, is often selected for the treatment of immune thrombocytopenia (ITP) that is refractory to corticosteroids. Response to rituximab occurs in up to 40% of patients, allowing them to avoid urgent splenectomy and other therapies. However, rituximab has some serious toxicities and is costly, and the reasons for treatment failure are unclear.
To examine features of ITP associated with nonresponse to rituximab, an investigative team examined the spleens of 12 ITP patients refractory to rituximab, 11 ITP patients never treated with the drug, and 9 controls without ITP undergoing splenectomy.
Results showed that in rituximab nonresponders:
The ratio of splenic T-suppressor cells (Th1) to T-regulator…