Flow Cytometric Assessment of T-cell Chronic Lymphoproliferative Disorders

Flow cytometry is frequently used in the evaluation of potential T-cell lineage lymphoproliferative disorders. Although flow cytometry is a useful tool, interpretation of the results can be challenging, because T-cells lack an easily analyzed structural element that can provide a surrogate marker of clonality such as immunoglobulin light chains on B-cells. Thus, routine T-cell phenotyping assays in the clinical laboratory require the comprehensive analysis of several T-cell-associated antigens. Although the detection of aberrant patterns of T-cell antigen expression can be helpful in establishing a diagnosis of T-cell malignancy, these patterns are not always disease specific, and some can overlap significantly with T-cell phenotypes observed in reactive conditions. Thus, arriving at an accurate diagnosis requires correlation of the flow cytometry results with the clinical, morphologic, and molecular results. Furthermore, the integration of these varied pieces of information into a cogent diagnosis requires an understanding of T-cell biology. In this review, the use of flow cytometry to identify T-cell lymphoproliferative disorders, particularly in peripheral blood and bone marrow specimens, is discussed, and a brief overview of T-cell biology to aid the reader in understanding the significance of the flow cytometry results is provided.