Increased Levels of Circulating Endothelial Progenitor Cells in Human T-cell Lymphotropic Virus Type I Carriers

Abstract

HTLV-I-transformed T cells secrete biologically active forms of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (b-FGF). In addition, HTLV-I-transformed cells have a high capacity of adhesion to endothelial cells. We measured the circulating endothelial progenitor cells (EPCs) and mature endothelial cells (MECs) by flow cytometry in 27 HTLV-I carriers in comparison to 30 healthy, age- and gender-matched subjects. All subjects had HTLV-I positivity confirmed by Western blot and/or polymerase chain reaction (PCR). The numbers of different subpopulations of EPCs and MECSs were evaluated by four-color flow cytometry using a panel of monoclonal antibodies. All reactions were done in duplicate to confirm reproducibility of the results. The median age of all 27 HTLV-I carriers enrolled in this study was 45 years (range: 27-65 years); 11 (41%) were male and 16 (59%) were female. The median age of the 30 healthy subjects in the control group was 45.5 years (range: 20-63 years); 11 (36.6%) were male and 19 (63.4%) were female. The number of EPCs was significantly higher in HTLV-I carriers (median 0.8288 cells/μL, range: 0.0920-3.3176 cells/μL) as compared to control group (median 0.4905 cells/μL, range: 0.0000-1.5660 cells/μL) (p= 0.035). In contrast, the median of the MECs in the HTLV-I carriers was 0.6380 cells/μL (range: 0.0473-5.7618 cells/μL) and 0.4950 cells/μL (range: 0.0000-4.0896 cells/μL) in the control group, with no statistical difference (p = 0.697). We demonstrated that EPCs, but not MECs, are increased in the peripheral blood of HTLV-I carriers.