ABSTRACT
Interleukin 12 [IL-12] is an important cytokine produced by monocytes and macrophages. It up regulates Th1 cytokines production especially IFNgamma and inhibits the expression of Th2 cytokines, so, its main function is the regulation of the bias of the immune system towards Th1 or Th2 response through a balance with IL-4 early in the immune response. This work was done to evaluate the serum and bronchoalveolar lavage [BAL] IL-12 in asthmatic patients compared with tuberculous patients and patients with primary lung cancer, to assess the impact of IL-12 on Th1-Th2 cytokines profile which determine the type of the response in these different diseases and to propose its potential clinical usefulness. The study included 4 groups: group I consisted of 20 asthmatic patients, group II: 10 patients who had pulmonary TB, group III: 10 patients with bronchogenic carcinoma, and group IV: 20 normal individuals. For all groups IL-12 was estimated in serum and [BAL] fluid using ELISA technique. Considering the results, IL-12 was significantly decreased in asthmatic patients and it increased with hyposensitiz ation, highly significantly increased in active pulmonary TB and significantly increased in localized bronchogenic carcinoma. It was concluded that IL-12 plays a central role on Th1-Th2 cytokines balance, being decreased in allergic conditions, i.e., producing immunological Th2, shift which is corrected to Th1 pathway by hyposensitization, hence, it may be of diagnostic and therapeutic values in bronchial asthma