Learning from leprosy: insights into contemporary immunology from an ancient disease

Leprosy provides an ideal model to study immune responses in humans and in skin. Learning from leprosy, we have gained insight into mechanisms of host resistance and susceptibility to infection. New paradigms include the role of Th1/Th2 cytokines, the ability of CD1 to present nonpeptide antigens to T cells, the ability of microbial lipoproteins to stimulate antimicrobial activity in monocytes and the demonstration that T cells can mediate a direct antimicrobial activity through release of granulysin. Together, these findings provide a rationale for developing new strategies to treat and prevent infectious disease.