Scientific American Magazine

By defining and defending the self, the immune system makes life possible; malfunction causes illness and death. Study of the system provides a unifying view of biology

Environmental and genetic signals cue cells as they differentiate into the many lineages that recognize foreign antigens and fight off invaders

Cells of the immune system recombine gene fragments to create the millions of receptors needed to identify and attack the myriad pathogens encountered throughout life

The human immune system has developed several elegant processes that allow it to repel foreign invaders and yet not attack the body itself

When bacteria, viruses and other pathogens infect the body, they hide in different places. Each component of the immune system is most adept at rousting trespassers from one location

The AIDS virus exploits the immune system to replicate itself. New findings are showing how it wreaks havoc on the body's defenses

Misguided assaults on the self produce multiple sclerosis, juvenile diabetes and other chronic illnesses. Promising therapies are emerging

In allergic individuals, parts of the immune system misdirect their power at innocuous substances, producing sometimes deadly symptoms

New technologies and insights into the molecular underpinnings of the immune system provide the basis for novel approaches to vaccines and other therapies

As host and pathogen evolve together, will the immune system retain the upper hand?