Estudo da função tímica em portadores de HTLV-1 com PET/MAH

Abstract

In HTLV-1 infeccions 90% of carriers remain asymptomatic, 2-3% develop Adult T-cell leukemia/lymphoma (ATL) and 0.25-4% develop HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP). In HAM/TSP, specific CD8 + T cell infiltrates are found in the marrow that destroy infected CD4 + T cells, leading to a chronic activated immune response. Recently emigrated T cells (or naïve T cells) have excised circles by the rearrangement of T cell receptor (TREC) genes that do not double in cell proliferation, being a good indicator to quantify the number of naïve T cells and thus evaluate the thymic function. This study aimed to verify the thymic function of patients with HTLV-1 infection by quantifying the number of TREC in peripheral blood mononuclear cells. This is a cross-sectional, analytical study of 39 patients over 18 years of age, divided into two groups: HAM/TSP (PET) and without HAM/TSP (NPET). We performed a clinical and physiotherapeutic evaluation, blood collection, lymphomononuclear cell separation, DNA and RNA extraction, absolute TREC curve, DNA and RNA quantification, TREC particle detection and quantification, cDNA synthesis, cytokine IL-7 and statistical analysis with the Mann-Whitney tests and Spearman's correlation, with p ≤ 0.05 as significance level. Of the 39 patients studied, two were excluded from the study because they presented autoimmune disease. Regarding the comparison between groups of TREC quantification: there was a difference between the PET and NPET groups (p = 0.01), in patients with age ≤59 years between the PET and NPET groups (p = 0.04), in the (p = 0.003) and the group with a wheelchair and without a wheelchair (p = 0.05). As for the comparison of IL-7 gene expression between groups: in the NPET group there was a difference between the group ≤59 years and the ≥60 years (p = 0.02), in the female there was a difference between the PET and NPET groups (p = 0.04). Thymic function was impaired in patients with HTLV-1 with HAM/TSP compared to those without HAM/TSP, as there was a loss in naïve T cell production in this population, shown by the differences between variables in both PET and NPET groups With respect to the quantification of TREC. Although the importance of this compromise in the triggering and / or evolution of HAM/TSP is not yet clear, it is inferred that the reduction of naïve T cell production can alter the immunological response in these patients, directly affecting their clinical picture.