Eje interleucina 12/interferón gamma en pacientes de tuberculosis en una región europea con alta incidencia de enfermedad

The integrity of the interleukin 12/interferon gamma (IL-12/INF-γ) axis has been shown to be essential in the control of the Mycobacterium tuberculosis infection. The aim of this study was to assess whether the high incidence of tuberculosis (TB) in Galicia, Spain, could be related to an altered response in the IL-12/INF-γ axis in patients with TB. We studied 20 TB patients and 21 healthy controls: 7 with positive Tuberculin Skin test (TST+) and another 14 with TST–. The study of the IL-12/INF-γ axis was conducted by the analysis of INF-γ levels (in serum and supernatants of non-activated and activated cells) and by the cellular expression of IL-12Rβ1 and INF-γR1 in lymphocytes and monocytes, respectively. The assays were performed at baseline levels and after in vitro stimulation of peripheral blood mononuclear cells with phytohaemagglutinin (PHA) and purified protein derivative (PPD). Responses in patients and in healthy controls were analysed and compared. PHA and PPD in vitro stimulation significantly increased INF-gamma levels and the cellular expression of IL-12Rβ1 and INF-γR1 receptors compared to baseline levels in both TB patients and healthy controls (either with positive or negative TST). Our results suggest that there is an adequate immune response in all groups. Although the IL-12/INF-γ axis may have other abnormalities not analysed in this work, the functionality of the IL-12/INF-γ axis is preserved in the patients analysed with TB in Galicia. The high rates of disease historically observed in this community does not seem to be caused by a malfunction of the immune response at this level.