The immune system is all that stands between us and the hordes of microbes, such as the HIV virus pictured below, that threaten us constantly. But how does the system work? In the first of two supplements, the origins of the human immune system come under the microscope
THE longest that anyone has lived without an effective immune system is 12 years. Doctors at a hospital in Houston, Texas, managed to keep a boy born with “severe combined immunodeficiency” (SCID) alive for this long. But to do so they had to enclose him in the microbe-free world of a plastic…
