Tuberculosis remains one of the world's greatest public health challenges: 2 billion persons have latent infection, 8 million people develop active tuberculosis annually, and 2-3 million die. Recently, significant advances in our understanding of the human immune response against tuberculosis have occurred. The present review focuses on recent work in macrophage and T-cell biology that sheds light on the human immune response to tuberculosis. The role of key cytokines such as interferon-gamma is discussed, as is the role of CD4+ and CD8+ T cells in immune regulation in tuberculosis, particularly with regard to implications for vaccine development and evaluation.