Análise fenotípica de linfócitos T do sangue periférico na leishmaniose visceral humana

Abstract

Visceral leishmaniasis is a chronic systemic infectious disease affecting organs of the mononuclear phagocytic system, caused by a trypanosomatid of the genus Leishmania. In recent years, it has become a serious public health problem, and when left untreated, it can be fatal. The disease is characterized by a wide range of clinical manifestations ranging from asymptomatic or subclinical cases to severe visceral leishmaniasis. To contain the progression of the disease caused by the intracellular parasite, an immune response with a predominantly Th1 profile is necessary. However, other response profiles (Th2, Treg, and Th17) can establish a regulatory environment, interfering with the prognosis. The study evaluated the immunological behavior of treated patients and control individuals from endemic areas through phenotypic and functional analysis of the T lymphocyte repertoire. The results demonstrated a strong positive correlation between T lymphocyte populations expressing molecules (CD27 and CD28) in both analyzed groups, also observed in populations of T cells expressing the PD-1 molecule. Among memory TCD8+ lymphocyte populations (CD8+ CD127high CXCR-3+) and exhausted TCD8+ lymphocyte populations (CD8+ CD127low TIM-3+), a strong positive correlation was also evident in both analyzed groups. The correlation between regulatory T cells (Treg) and populations of TCD4+ (CD27+ and CD28+) and TCD8+ (CD27+ and CD28+) lymphocytes demonstrated a positive correlation only in the treated patient group. It is concluded that there may be a balanced environment, constituted by different populations of T cells, both by the expression of co-stimulatory molecules in memory populations and by the expression of exhaustion molecules and the presence of Treg lymphocyte populations, mainly in the treated patient group, enabling the individual to control the progression of the disease or clinically recover after treatment.