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Open Access Case report

Prozone effect of serum IgE levels in a case of plasma cell leukemia

Giampaolo Talamo*, William Castellani and Nathan G Dolloff

Author Affiliations

Penn State Hershey Cancer Institute, 500 University Drive, Hershey, PA 17033 USA

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Journal of Hematology & Oncology 2010, 3:32  doi:10.1186/1756-8722-3-32

Published: 10 September 2010

Abstract

We describe a case of multiple myeloma (MM) and secondary plasma cell leukemia (PCL) secreting IgE-kappa immunoglobulin. To our knowledge, only 2 cases of IgE-producing secondary PCL have been reported in the medical literature. In our patient, the only tumor marker available for monitoring the therapeutic response to chemotherapy and allogeneic stem cell transplantation was the quantitative M component at serum protein electrophoresis (SPEP), because serum free light chains were in the normal range, Bence-Jones proteinuria was absent, and quantitative serum IgE levels provided inaccurate and erratic results, due to the prozone effect. This is a laboratory phenomenon that occurs when antigen excess interferes with antibody-based methods requiring immune complex formation for detection. It is important to recognize the presence of a prozone effect, because it can produce falsely normal results, and therefore it could lead clinicians to incorrect assessment of the response to therapy.