Assessment of clonality in T-cell large granular lymphocytic leukemia: flow cytometric T cell receptor Vβ repertoire and T cell receptor gene rearrangement.

The usefulness of flow cytometric variable β-chain repertoire (FC-Vβ) and T-cell receptor gene rearrangement (TCR-GR) analyses for differentiating T-cell large granular lymphocytic leukemia (T-LGLL) from reactive T-large granular lymphocyte (T-LGL) lymphocytosis has been insufficiently studied to date. In this study, we analyzed the diagnostic value of TCR-GR and FC-Vβ analysis in T-LGLL, and compared these results. In our study, FC-Vβ analysis was positive in all cases of T-LGLL, and clonality assessment of FC-Vβ had equal sensitivity and specificity to GeneScanning analysis but was more sensitive than heteroduplex analysis. Suspected T-cell clonality can best be addressed by evaluating two TCR targets (TCRβ and TCRγ), either in parallel or consecutively. Signal transducer and activator of transcription 3 (STAT3) mutation may provide a diagnostic tool for classifying some cases of T-LGL lymphocytosis as true T-LGLL. Our results further demonstrate a significant correlation of STAT3 mutation with pure red cell aplasia, neutropenia, hepatomegaly, β2-microglobulin and anemia.