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Hematology - Immunology

Chronic Myeloid Leukemia Patients in Prolonged Remission following Interferon-a Monotherapy Have Distinct Cytokine and Oligoclonal Lymphocyte Profile
Published: Tuesday, August 09, 2011
Author: Anna Kreutzman et al.

by Anna Kreutzman, Peter Rohon, Edgar Faber, Karel Indrak, Vesa Juvonen, Veli Kairisto, Jaroslava Voglová, Marjatta Sinisalo, Emília Flochová, Jukka Vakkila, Petteri Arstila, Kimmo Porkka, Satu Mustjoki

Before the era of tyrosine kinase inhibitors (TKIs), interferon-alpha (IFN-a) was the treatment of choice in chronic myeloid leukemia (CML). Curiously, some IFN-a treated patients were able to discontinue therapy without disease progression. The aim of this project was to study the immunomodulatory effects of IFN-a in CML patients in prolonged remission and isolate biological markers predicting response. Due to rarity of patients on IFN-a monotherapy, a relatively small cohort of patients still on treatment (IFN-ON, n?=?10, median therapy duration 11.8 years) or had discontinued IFN-a therapy but remained in remission for >2 years (IFN-OFF, n?=?9) were studied. The lymphocyte immunophenotype was analyzed with a comprehensive flow cytometry panel and plasma cytokine levels were measured with multiplex bead-based assay. In addition, the clonality status of different lymphocyte subpopulations was analyzed by TCR ?/d rearrangement assay. Median NK-cell absolute number and proportion from lymphocytes in blood was higher in IFN-OFF patients as compared to IFN-ON patients or controls (0.42, 0.19, 0.21×109/L; 26%, 12%, 11%, respectively, p<0.001). The proportion of CD8+ T-cells was significantly increased in both patient groups and a larger proportion of T-cells expressed CD45RO. Most (95%) patients had significant numbers of oligoclonal lymphocytes characterized by T-cell receptor ?/d rearrangements. Strikingly, in the majority of patients (79%) a distinct clonal V?9 gene rearrangement was observed residing in ?d+ T-cell population. Similar unique clonality pattern was not observed in TKI treated CML patients. Plasma eotaxin and MCP-1 cytokines were significantly increased in IFN-OFF patients. Despite the limited number of patients, our data indicates that IFN-a treated CML patients in remission have increased numbers of NK-cells and clonal ?d+ T-cells and a unique plasma cytokine profile. These factors may relate to anti-leukemic effects of IFN-a in this specific group of patients and account for prolonged therapy responses even after drug discontinuation.