Study of peripheral lymphocytes apoptosis in childhood tuberculosis

ABSTRACT

In a trial to understand some aspects of immunopathogenesis of active tuberculous infection in children, we studied the spontaneous and Mycobacterium tuberculosis [MTR]-induced apoptosis of lymphocytes in children with tuberculous infection. This study included 18 newly diagnosed tuberculous patients [11 pulmonary and 7 lymphadenopathy] with age range of 4-15 years [mean 10.7 +/- 3.1 y] in addition to 9 contacts with positive tuberculin test and 9 healthy tuberculin non-reactors with matched age and sex. Diagnosis of tuberculosis was confirmed by smear positivity, Bactec culture for T.B or biopsy. From each patient and control peripheral blood mononuclear cells [PBMC] were obtained and subjected to study of apoptosis both spontaneously and after stimulation with atypical mycobacterial culture by TUNEL Method. The mean percentages of spontaneous apoptosis were 7.83 +/- 3.29, 1.22 +/- 0.44 and 1.0 +/- 0 in tuberculous patients, tuberculin positive contacts and healthy negative control respectively. After culture, the mean percentages of apoptosis increased to 16 +/- 7.15, 4.77 +/- 1.85 and 2.33 +/- 0.71 in patients, tuberculin reactor contacts and healthy non- reactor groups respectively. Spontaneous apoptosis was significantly higher in patients than contact tuberculin-reactors and healthy non reactors [P<0.001] without significant difference between the latter 2 groups. After culture, apoptosis in patients was significantly higher than control groups [P < 0.001] and tuberculin reactor contacts had significantly more apoptosis than healthy non reactors [P=0.002]. There was no significant difference in apoptosis increment between pulmonary or tuberculous lymphadenopathy patients. There was highly significant correlation between tuberculin diameter and incremement of apoptosis [P=0.006]. It could be concluded that apoptosis is directly involved in the immunopathogenesis of tuberculosis in children. It affects both primed and non primed lymphocytes and is related to the state of hypersensitivity