Flow cytometric evaluation of CD200 as a tool for differentiation between chronic lymphocytic leukemia and mantle cell lymphoma

Background In the majority of cases, flow cytometry enables the differentiation of chronic lymphocytic leukemia (CLL) from mantle cell lymphoma (MCL). However, the diagnosis of CLL becomes challenging when CD23 is not expressed by the leukemic cells or in cases of MCL expressing CD23. CD200 is a membrane glycoprotein expressed on a subset of T and B lymphocytes. Its expression has been observed on human myeloma, plasma cells, and CLL cells. Aim of the work We investigated the pattern of expression of CD200 in CLL and MCL patients, aiming to clarify its possible role in differentiating these often overlapping disorders. Patients and methods This study was carried out on 30 patients with newly diagnosed CLL and 10 patients with MCL. Flow cytometric immunophenotyping was performed using the CD200 monoclonal antibody in addition to the standard panel of chronic lymphoproliferative diagnosis. Results CD200 was expressed in 100% of CLL cases with moderate intensity compared with only 10% of MCL cases with low intensity. Conclusion CD200 is a powerful addition to the routine flow cytometric panel in the differentiation between CLL and MCL with high sensitivity and specificity.