As our understanding of the intricacies of our immune system grows, we can apply this knowledge to develop new therapies for human disease — articles in this issue show how. The contribution that immunologists have made to human health is clearly seen in the field of vaccination. The eradication of smallpox and the prevention of other life-threatening infectious diseases are major success stories. However, vaccines are currently unavailable for many diseases, including malaria, which claims more than 2 million lives per year. Future vaccine strategies for malaria are discussed on page 117 by Michael Good. In addition, this month's Web Watch features The Vaccine Page — a pro-vaccination web resource. The potential adverse side effects of vaccinations, however, cause concern for some people; see the Science and Society article on page 160 by Christopher Wilson and Edgar Marcuse.

Technology and our understanding of the immune system have advanced in parallel. New technologies for replacing organ function, and the barriers to their application, are described by Marilia Cascalho and Jeffrey Platt on page 154. New therapies for human disease will also be developed as we learn more about how immune cells respond to their environment. Nicholas Lukacs discusses, on page 108, how the inflammation that occurs during asthma is controlled by the expression of chemokines and their receptors. Targeting these molecules could enable us to develop more specific therapies for this chronic disease.

Recent work investigating the initiation and progression of the autoimmune disease systemic lupus erythematosus is discussed by Mark Shlomchik, Joseph Craft and Mark Mamula on page 147. They describe an integrated model, whereby interactions between B and T cells promote the loss of tolerance to self-antigens and ultimately result in disease.