Cytokines as immunomodulators in tuberculosis therapy.

The use of cytokines for therapeutic purposes is limited by their high cost and toxicity. Nevertheless, the emergence of extensively drug-resistant tuberculosis (XDR TB), for which chemotherapy is ineffective, has again made cytokine-based therapy attractive as one of the last available options. The results of clinical trials treating pulmonary tuberculosis with cytokines have not been encouraging, making it clear that therapeutic strategies utilizing a single cytokine are inadequate. To develop effective cytokine-based XDR TB therapies, more basic research will be needed to achieve a better understanding of how cytokines promote a successful immune response. We not only have to investigate cytokines already known to participate in tuberculosis, but also the role of other cytokines and chemokines that may enhance both the mycobacterial killing activity of effector cells and the restriction of bacterial intracellular multiplication. There are already several patents involving cytokines for therapeutic use, in the hope of stimulating the immune system in a variety of infectious diseases, including tuberculosis. The validity of these patents needs to be reassessed from a clinical standpoint, and new applications of patents concerning cytokines potentially useful in XDR TB treatment should be encouraged.