Progress of research on role of T lympnocyte subsets in evolvement of pulmonary tuberculosis and diabetes mellitus comorbidity

Pulmonary tuberculosis (PTB) and diabetes mellitus (DM) were common and highly prevalent in hospitals, and there was biodirectional association between the two types of diseases. The DM patients had the abnormal glucose metabolism and alteration of immune system, which may lead to the increase of risk of PTB; PTB may again exacerbate the metabolic disorders to form a vicious circle, which increased the difficuties of treatment and manatgment and also raised the mortality rate. T lymphocyte subsets were crucial to the immune response of the patients with PTB and DM, and the changes of their number and function affected the progression of disease and therapeutic effect. Under the state of DM, the damaged congenital and adaptive immunity, the decreased helper T cell (Th) type 1 cytokines, the delayed start of T cell-mediated adaptive immune response and the declined defense capability to Mycobacterium tuberculosis infection may lead to the increase of susceptibility to PTB. The broken balance of Th1, Th17 and Regulatory T cells (Treg) may induce the excessive proinflammatory reactions and destroy the immune homeostasis of the patients with PTB-DM comorbidity. High blood glucose level increases the number of Treg cells, decreses the number of effector T cells, reduces the immunity and accelerates the deterioration of diseases. The T lymphocytes subsets have great significance in assessment of the immune state of the patients with PTB-DM comorbidity and are essential for assessment of anti-tuberculosis effect, prediction of risk for infections, judgment of prognosis and long-term health management. Further study on the mechanisms may provide theoretical bases for optimizing clinical treatment programs and developing new therapies so as to improve the prognosis of the patients.