Differential Expression of CD200 in B-chronic Lymphoproliferative Disorders by Multicolour Flow Cytometry

B-Chronic lymphoproliferative disorders (B-CLPDs) are heterogeneous group of disorders with variable clinical presentations and outcomes. They are classified into : chronic lymphocytic leukaemia (CLL), B-cell prolymphocytic leukaemia (B-PLL), hairy cell leukaemia (HCL), and mantle cell lymphoma (MCL), marginal zone lymphoma (MZL), follicular lymphoma (FL) and lymphoplasmacytic lymphoma/WaldenstrÖm macroglobulinaemia (LPL/WM) in leukaemia phase.

Characterization of CLPDs by immunophenotyping (IPT) has become an important and widely used method in hematology. Immunophenotyping is indispensable for the diagnosis of B-CLPDs through recognition of restricted light chain expression and characteristic phenotypes of separate entities.

Immunophenotypic characterization of lymphoid neoplasms is important for diagnosis, sub-classification, and staging and can also play a role in monitoring minimal residual disease. However, the differential diagnosis may be difficult to resolve in some cases, for example, between B-cell neoplasms with full or partial CD5 expression.

CD200 has recently been identified as a potentially useful antigen for flow cytometric immunophenotyping of lymphoid neoplasms, particularly those of the B lineage.

CD200 belongs to the immunoglobulin superfamily and is composed of a light chain-like structure with two extracellular variable- and constant-like domains followed by a transmembrane segment and a cytoplasmic tail.5 CD200 is expressed by various cell types, including B cells, a subset of T cells (including activated T cells), thymocytes, endothelial cells, and neurons .