Evaluation of the performance of immunological parameters as indicators for clinical progression of chronic HTLV-1 infection

Abstract

This study evaluated the performance of single and combined laboratory parameters, B-lymphocyte percentages (%LB), T/B cell ratio and %CD8 +HLA-DR+/CD8+, to differentiate asymptomatic cases (AS) from HAM/TSP patients (HT) within a population of HTLV-1 seropositive cases. Percentage indices demonstrated that each parameter alone presented moderate performance, with co-negativity of 83 and 91% for %LB and T/B cell ratio, respectively, and co-positivity of 78% for %CD8+HLA-DR +/CD8+. Combined analysis (%CD8+HLA-DR +/CD8+ and T/B cell ratio) did not show any substantial performance enhancement (co-positivity = 75% and co-negativity = 74%). Likelihood ratio analysis using different value ranges for the separate parameters revealed that HTLV-1 seropositive cases with %LB<7%, T/B cell ratio>11 and %CD8+HLA-DR+/CD8+>70% would have, respectively, 11, 19 and 10 times greater chance of belonging to the HT group. Therefore, use of these phenotypic indicators as complementary laboratory methods for monitoring the clinical progression of chronic HTLV-1 infection is recommended.