Interleukin-12, an emerging anti-tumour cytokine

Interleukin 12 is a multifunctional cytokine secreted by a wide variety of cells including macrophages and B cells and promotes cell-mediated immunity by its ability to selectively augment Th-1 type immune responses. This pleiotropic cytokine exerts numerous effects on T and NK cells, resulting in an enhancement of cytolytic activity and direct stimulation of IFN-gamma production and studies have demonstrated that this cytokine plays an important role in the promotion of the host resistance to infection by bacterial, fungal and protozoan pathogens. IL-12 has also been shown to cause tumour regression and reduce metastasis in animal models, due to both the promotion of antitumour immunity and also to the significant inhibition of angiogenesis and up-regulation of E-cadherin, a metastasis suppressor. Recent reports using local administration of IL-12 to the tumour site by retroviral vectors and 'gene gun' techniques have resulted in a significant reduction of tumour mass, with complete eradication occurring in several cases. The effects of IL-12 in patients with cancer are currently under investigation. Thus, interleukin-12 represents a cytokine with potent antitumour effects and may therefore be an attractive agent in anticancer therapy.