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Background: Leprosy is an infectious disease caused by the intracellular pathogen Mycobacterium leprae, which is a microorganism that evades the host’s immune response. The mechanisms regulating immune circumvention are not fully understood. It has been proposed that the pathogen alters the mechanisms regulating the immune response of the host to escape immune surveillance. Thus, regulatory T cells are important immune elements that must be investigated. To escape the immune response using regulatory properties or natural regulatory T cells (nTreg), M. leprae increases the number of nTregs observed in the steady-state. Because nTregs are thymus derived, one way to verify if M. leprae infection induces de novo nTreg cells is to determine the nature of recent thymus emigrant nTregs in leprosy patients and compare the cells to healthy controls. Objectives: In this study, we (i) quantified the regulatory T cells in the peripheral blood of leprosy patients compared to healthy age-matched controls, (ii) determined whether these cells show a phenotype of recent thymic emigrants, and (iii) evaluated the cytokine profile in plasma samples. All of the studies were performed using flow cytometry. Results: We found higher levels of nTreg cells during early periods of the disease. Additionally, there was a continuous decrease in nTreg cells throughout the treatment. Moreover, the nTregs were recent thymic emigrants, as shown by the expression of a specific marker (PTK7).We did not find any difference in the cytokine profile when comparing patients and controls. Conclusion: The levels of CD4+CD25highFoxp3+ T cells in patients with leprosy are most likely evidence of thymic output. In addition, blood levels of CD4+CD25highFoxp3+PtK7+ can be used to monitor treatment progress in leprosy. |
