This volume highlights the latest information and newest understanding in immunology. It encompasses both basic research and clinical applications of the latest immunologic knowledge. NOTE: Annals volumes are available for sale as individual books or as a journal. For information on institutional journal subscriptions, please visit www.blackwellpublishing.com/nyas . ACADEMY MEMBERS: Please contact the New York Academy of Sciences directly to place your order ( www.nyas.org ). Members of the New York Academy of Science receive full–text access to the Annals online and discounts on print volumes. Please visit www.nyas.org/membership/main.asp for more information about becoming a member.