Role of serum interleukin-18 in the assessment of activity of tuberculosis

ABSTRACT

This study is carried out to evaluate the role of interleukin-18 [IL-18] in the immune response against Mycobacterium tuberculosis [M. tuberculosis] and the reliability of its serum level in the assessment of tuberculous disease activity. It included 40 subjects who were classified into three groups, group I [included 20 patients with active pulmonary tuberculosis], group II [included 10 patients with active extrapulmonary tuberculosis], and group III [included 10 healthy subjects served as controls]. All subjects were investigated, before and 3 months after start of antituberculous treatment, by conventional methods to assess tuberculous disease activity [clinical features, ESR, sputum direct smear for acid fast bacilli and chest X-ray] and measurement of serum IL-18 level. In group I, 16 patients showed good response to treatment and became inactive and showed significant reduction in serum IL-18 level, while the remaining 4 patients showed poor response to treatment and still active and their serum IL-18 level did not change significantly. In group II, 9 patients showed good response to treatment and became inactive and their serum IL-18 level was reduced significantly. In conclusion, serum IL-18 plays an important role in the immune response against M. tuberculosis, as it was higher in patients than in the healthy controls. Serum IL-18 level is directly proportionate to the tuberculous disease activity and severity and it caries a prognostic value, where patients with high serum IL-18 level had good response to treatment, while patients with low serum IL-18 level had poor response to treatment