Soluble Cytotoxic T-Lymphocyte Antigen-4 (CTLA-4) in Chronic Myeloid Leukemia and its Association with Total and Differential Leukocytes Count

Background: Chronic myeloid leukemia (CML) is a myeloproliferative disorder characterized by the presence of Philadelphia chromosome in the vast majority of cases. Although tyrosine kinase inhibitors (TKIs) are very effective in the treatment of this disorder, they cannot completely eliminate the leukemic cells indicating other players in the body fighting against this malignancy.

Aims: To evaluate serum concentrations of soluble cytotoxic T-lymphocyte antigen-4 (sCTLA-4) and its correlation with total and differential leukocytes count in patients with Chronic myeloid leukemia.

Subjects and Method: This case-control study included 48 imatinib-resistant Chronic myeloid leukemia patients, and 42 family unrelated, age-matched healthy subjects. Blood samples were obtained from each participant, from which sera were separated and soluble cytotoxic T-lymphocyte antigen-4 concentration was measured by enzyme-linked immunosorbent assay (ELISA). Demographic data for patients and controls were recorded through direct interview, with laboratory data for patients were extracted from their records.

Results: Serum concentration of soluble cytotoxic T-lymphocyte antigen-4 was found to be significantly dropped in Chronic myeloid leukemia patients compared to controls (26.38 ± 4.35 pg/ml vs. 37.19 ± 11.08 pg/ml). Furthermore, soluble cytotoxic T-lymphocyte antigen-4 was inversely (although not significantly) associated with the total number of leukocytes and neutrophils, while this concentration was positively and significantly with lymphocytes count (r = 0.606, P < 0.001).

Conclusions: Soluble cytotoxic T-lymphocyte antigen-4 is down-regulated in imatinib-resistant Chronic myeloid leukemia patients which is associated with increased neutrophil counts.