EXPRESSION OF INTERLEUKIN-2Rα CHAIN (CD25) ON PERIPHERAL BLOOD LYMPHOCYTES IN HTLV-I ASSOCIATED MYELOPATHY /TROPICAL SPASTIC PARAPARESIS PATIENTS

Background-Mashhad, a city in northern Iran, is a newly recognized endemic area for a retrovirus, the Human T-cell Lymphotropic Virus type I (HTLV-I). This virus is the causative agent of a chronic slowly progressive cord syndrome called HTLV-I associated with Human T-cell virus type I-associated myelopathy or/tropical spastic paraparesis (HAM/TSP) and has tropism for CD4+ T- cells, which results in T-cell activation that escape the autocrine pathway. Objective-The purpose of this study was to determine the immuno-phenotypic features of peripheral blood lymphocytes of HAM/TSP patients, especially differential expression of interleukin-2 receptor α (IL-2Rα) chain on the surface of the T-cells of HAM/TSP patients, HTLV-I carriers and healthy controls. Methods-Subjects in this case-control study included 20 HAM/TSP patients, 14 HTLV-I carriers and 12 healthy controls. The absolute white blood cell count and the differential cell count were determined by hematologic analysis and the relative and absolute number of peripheral blood CD3+ CD25+ T-cells were determined by flowcytometry. Results-The relative number of lymphocytes (36±9%), relative number of CD3+ cells (74±7%) and the relative and absolute number of CD25/3+ cells (21±8%, 0.309±0.155 x109/1) were significantly higher in HAM/TSP patients than healthy controls (29±7%, 68±4%, 13±3%, 0.187±0.065 x 109/1) (p<0.05). The relative lymphocyte (36±5%) and relative CD25/3+ (18±5%) cell counts were significantly higher in carriers in comparison with controls. No significant differences were present in these parameters between carriers and HAM/TSP patients. Conclusion-This differential pattern of T-cell activation markers among the study groups may have striking diagnostic and therapeutic implications.