Single-Antibody Evaluation of T-Cell Receptor β Constant Chain Monotypia by Flow Cytometry Facilitates the Diagnosis of T-Cell Large Granular Lymphocytic Leukemia.

Objectives: The diagnosis of T-cell large granular lymphocytic leukemia (T-LGLL) is challenging because of overlapping immunophenotypic features with reactive T cells and limitations of T-cell clonality assays. We studied whether adding an antibody against T-cell receptor β constant region 1 (TRBC1) to a comprehensive flow cytometry panel could facilitate the diagnosis of T-LGLL.

Methods: We added TRBC1 antibody to the standard T-cell and natural killer (NK) cell panel to assess T-cell clonality in 56 T-LGLLs and 34 reactive lymphocytoses.

T-cell clones of uncertain significance are highly prevalent and show close resemblance to T-cell large granular lymphocytic leukemia. Implications for laboratory diagnostics.

Benign clonal T-cell expansions in reactive immune responses often complicate the laboratory diagnosis T-cell neoplasia. We recently introduced a novel flow cytometry assay to detect T-cell clones in blood and bone marrow, based on the identification of a monophasic T-cell receptor (TCR) β chain constant region-1 (TRBC1) expression pattern within a phenotypically distinct TCRαβ T-cell subset. In routine laboratory practice, T-cell clones of uncertain significance (T-CUS) were detected in 42 of 159 (26%) patients without T-cell malignancy, and in 3 of 24 (13%) healthy donors.

Flow cytometric evaluation of TRBC1 expression in tissue specimens and body fluids is a novel and specific method for assessment of T-cell clonality and diagnosis of T-cell neoplasms.

Background: Flow cytometric detection of T-cell clonality is challenging. The current available methodology for T-cell receptor (TCR) Vβ repertoire evaluation is a complex assay and has limited sensitivity especially for detecting low levels of disease. Therefore, there is an unmet need for a reliable, simple, and rapid assay to identify T-cell clonality.