The impact of interferon-alpha treatment on clinical and immunovirological aspects of HTLV-1-associated myelopathy in northeast of Iran

Human T-lymphotropic virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic inflammatory myelopathy. The pathophysiology of HAM/TSP is not yet fully understood; therefore, effective therapy remains a challenging issue. This study was designed to evaluate the efficacy of interferon-alpha (IFN-α) in HAM/TSP patients in the Northeast of Iran. Forty-nine patients with a definite diagnosis of HAM/TSP were enrolled in this clinical trial. For six months, the patients received three million international units of subcutaneous IFN-α-2b per each injection. The dose regimen was daily injection for the first month, three times administration per week for the months 2 and 3, twice weekly injection for the months 4 and 5 and weekly injection for the sixth month. The clinical and laboratory responses were evaluated based on neurologic examinations and immunovirological markers. IFN-α had significant but temporary effect on the motor and urinary functions of the patients. Comparing to the baseline values, proviral load was significantly decreased one month after treatment in responders (495.20 ± 306.87 to 262.69 ± 219.24 p = 0.02) and non-responders (624.86 ± 261.90 to 428.28 ± 259.88 p = 0.03). Anti‐HTLV-1 antibody titers were significantly decreased among responders (1152.1 ± 200.5 to 511.6 ± 98.2 p = 0.009) and non-responders (1280.1 ± 368.1 to 537.6 ± 187 p = 0.007). Flow cytometry showed no significant changes in CD4, CD8, CD4CD25 and CD16CD56 counts with IFN-α. The positive impact of IFN-α was observed during the treatment period with significant effects on some clinical aspects of HAM/TSP.