The
SCID Mouse
Research in immunology took a giant step forward with the development
and manipulation of the SCID
mouse. Lacing an enzyme necessary to fashion a functional
immune system of their own, SCID mice-like their human counterparts
with Severe Combined Immunodeficiency Disease (Immunodeficiency
Diseases)-are helpless not only to fight infection but also to reject
transplanted tissue.
In
the late 1980s, scientists transformed the SCID mouse into an in
vivo model of the human immune system. One group of researchers
painstakingly transplanted a human fetal thymus gland and lymph
nodes into the adult SCID mouse, then injected them with embryonic
human immune cells. Some of these cells traveled to the human thymus,
where they matured into T cells; others developed into working B
cells and macrophages, circulating through the lymph nodes. A second
group of researchers implanted mature human T cells in the SCID
mouse. Such systems amount to a living test tube, making it possible
to study the effects of drugs and of viruses, including HIV, in
an intact mammalian immune system.
