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Large granular lymphocyte (LGL) leukemia is a well-recognized disease of mature T-CD8+or less frequently natural killer cells; in contrast, monoclonal expansions of CD4+T-LGL have only been sporadically reported in the literature. In the present article we have explored throughout a period of 56 months the incidence of monoclonal expansions of CD4+T-LGL in a population of 2.2 million inhabitants and analyzed the immunophenotype and the pattern of cytokine production of clonal CD4+T cells of a series of 34 consecutive cases. Like CD8+T-LGL leukemias, CD4+T-LGL leukemia patients have an indolent disease; however, in contrast to CD8+T-LGL leukemias, they do not show cytopenias and autoimmune phenomena and they frequently have associated neoplasias, which is usually determining the clinical course of the disease. Monoclonal CD4+T-LGLshowed expression of TCRαβ, variable levels of CD8 (CD8−/+dim) and a homogeneous typical cytotoxic (granzyme B+, CD56+, CD57+, CD11b+/−) and activated/memory T cell (CD2+bright, CD7−/+dim, CD11a+bright, CD28−, CD62L−HLA-DR+) immunophenotype. In addition, they exhibited a Th1 pattern of cytokine production [interferon-γ++, tumor necrosis factor-α++, interleukin (IL-2)−/+, IL-4−, IL-10−, IL-13−]. Phenotypic analysis of the TCR-Vβ repertoire revealed large monoclonal TCR-Vβ expansions; only a restricted number of TCR-Vβ families were represented in the 34 cases analyzed. These findings suggest that monoclonal TCRαβ+/CD4+/NKa+/CD8−/+dimT-LGL represent a subgroup of monoclonal LGL lymphoproliferative disorders different from both CD8+T-LGL and natural killer cell-type LGL leukemias. Longer follow-up periods are necessary to determine the exact significance of this clonal disorder.

At present, a major challenge in the initial diagnosis of leukemia of large granular lymphocytes (LGLs) is to establish the clonal nature of the expanded population. In the present study we have analyzed by flow cytometry immunophenotyping the TCR-Vβ repertoire of 98 consecutive cases of persistent expansions of CD4+or CD8+brightCD3+/TCR-αβ+LGLs and compared the results with those obtained in molecular studies of TCR-β gene rearrangements. Fifty-eight cases were considered to be monoclonal in molecular studies whereas in the remaining 40 cases there was no evidence for monoclonality (11 cases were considered oligoclonal and 29 polyclonal). The TCR-Vβ repertoire was biased to the preferential use of one or more TCR-Vβ families in 96% of cases, a total of 124 TCR-Vβ expansions being diagnosed: one TCR-Vβ expansion in 71 cases and two or more TCR-Vβ expansions in 23 cases. The highest TCR-Vβ expansion observed in each case was higher among monoclonal (74 ± 19%) as compared to nonmonoclonal cases (24 ± 14%) (P= 0.001), as did the fraction of LGLs that exhibited a TCR-Vβ-restricted pattern (86 ± 16% and 42 ± 23%, respectively;P= 0.0001); by contrast, the proportion of cases displaying more than one TCR-Vβ expansion was higher in the latter group: 7%versus48%, respectively (P= 0.001). Results obtained in oligoclonal cases were intermediate between those obtained in polyclonal and monoclonal cases and similar results were observed for CD4+as for CD8+brightT-cell expansions. TCR-Vβ familiesexpressed in CD8+brightT-cell-LGL proliferations showed a pattern of distribution that mimics the frequency at which the individual TCR-Vβ families are represented in normal peripheral blood T cells. Assuming that a given proliferation of LGLs is monoclonal whenever there is an expansion of a given TCR-Vβ family of at least 40% of the total CD4+or CD8+brightT-cell compartment, we were able to predict clonality with a sensitivity of 93% and a specificity of 80%. By increasing the cut-off value to 60%, sensitivity and specificity were of 81% and 100%. In summary, our results suggest that flow cytometry immunophenotypic analysis of the TCR-Vβ repertoire is a powerful screening tool for the assessment of T-cell clonality in persistent expansions of TCR-αβ+LGLs.

The bcl‐2 oncogene has been involved in the genesis of various B‐cell neoplasms by means of encoding for p26, an apoptosis suppressor oncoprotein. The expression of p26 in lymphoproliferative disorders of large granular lymphocytes (LDLGL), a group of diseases whose mechanism leading to lymphocyte expansion is not yet clear, was not previously characterized. In order to further understand the biology of LDLGL, we compared the expression of p26 in CD8(+)lymphocytes of patients with CD3(+)LDLGL with that observed in normal individuals, patients with viral infection and patients with CD4(+)lymphoid neoplasms. We observed that upregulation of bcl‐2 expression is not involved in the genesis of lymphocyte expansion in CD3(+)LDLGL. By contrast, when compared to normal peripheral blood counterparts, CD8(+,bright)lymphocytes of patients with LDLGL express low levels of p26 whereas CD8(+,dim)lymphocytes express normal or only slightly reduced levels of this oncoprotein. A similar pattern of expression of p26 was found in situations in which CD8(+)lymphocytes represent reactive activated cells. © 1997 John Wiley & Sons, Ltd.

Introduction. Mast cell (MC) leukemia (MCL) is extremely rare. We present a case of MCL diagnosed concomitantly with acute myeloblastic leukemia (AML). Case Report. A 41-year-old woman presented with asthenia, anorexia, fever, epigastralgia, and diarrhea. She had a maculopapular skin rash, hepatosplenomegaly, retroperitoneal adenopathies, pancytopenia, 6% blast cells (BC) and 20% MC in the peripheral blood, elevated lactate dehydrogenase, cholestasis, hypoalbuminemia, hypogammaglobulinemia, and increased serum tryptase (184 μg/L). The bone marrow (BM) smears showed 24% myeloblasts, 17% promyelocytes, and 16% abnormal toluidine blue positive MC, and flow cytometry revealed 12% myeloid BC, 34% aberrant promyelocytes, a maturation blockage at the myeloblast/promyelocyte level, and 16% abnormal CD2−CD25+ MC. The BM karyotype was normal, and the KIT D816V mutation was positive in BM cells. The diagnosis of MCL associated with AML was assumed. The patient received corticosteroids, disodium cromoglycate, cladribine, idarubicin and cytosine arabinoside, high-dose cytosine arabinoside, and hematopoietic stem cell transplantation (HSCT). The outcome was favorable, with complete hematological remission two years after diagnosis and one year after HSCT. Conclusions. This case emphasizes the need of an exhaustive laboratory evaluation for the concomitant diagnosis of MCL and AML, and the therapeutic options.