Introduction: Th1 response is known to play a dominant role in the resistance to tuberculosis. Nevertheless, IFN gamma levels are frequently increased in tuberculous patients, especially at the site of the disease. It is also possible that the shift toward Th2 response is responsible for the loss of resistance. The aim of this study was to compare the Th1 function of peripheral blood cells and the levels of antimycobacterial antibodies in the serum of culture positive tuberculosis patients and healthy tuberculosis (Tb) contacts. The correlation between the levels of antimycobacterial antibodies and Th1 function of blood cells was also evaluated.
Material and methods: The material consisted of 51 tuberculous patients and 20 healthy persons, close contacts of tuberculosis patients. The ability of peripheral blood cells to secrete IFN gamma and IL-2 was estimated in whole blood cultures with PHA, PWM and tuberculin. The levels of IFN gamma and IL-2 in the supernatants of cultures was estimated via a commercial ELISA test. The levels of antimycobacterial antibodies was measured with commercial immunoenzymatic kits detecting IgG antibodies against 38 kDa + 16 kDa and IgG, IgA and IgM antibodies to 38 kDa + lipoarabinomannan (LAM).
Results: No difference was found in the secretion of IFN gamma and IL-2 after stimulation with PHA and PWM between the patients and contacts. The secretion of IFN gamma after stimulation with tuberculin was even greater in tuberculous patients than in contacts. The levels of IgG and IgA (38 kDa + LAM) were higher in tuberculous patients than in contacts. There was a negative correlation between the level of IgG anti 38 kDa + LAM and the ability of peripheral blood cells to secrete IFN gamma after non-specific stimulation in patients with tuberculosis.
Conclusions: Our study confirms the hypothesis that it is not the diminished production of Th1 cytokines, but rather the parallel overproduction of Th2 cytokines, which are essential in the development of tuberculosis.