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Disease and Resistance: The War Within |
Chapter: 16
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The Human Mouse Investigators seeking an AIDS vaccine and wishing to determine drug effectiveness need to know whether a prototype preparation can elicit antibody production in a good test animal. Drug producers require a small-animal model to bridge the gap between laboratory cultures and human trials. The search for a good animal model frustrated researchers until 1988, when two laboratory teams from California transplanted components of the human immune system into mice and produced what the media immediately labeled "the human mouse." The mice involved had been identified five years previously as having severe combined immunodeficiency (SCID), and immune disorder in which no B- or T-lymphocytes are produced. The animals had essentially no immune system. One team was led by Michael McCane, an immunologist at Stanford University. The researchers took thymus, lymph node, and liver tissue from a human aborted fetus and placed it under the capsulelike membrane surrounding the mouse's kidney. A week later they injected fetal immune cells into the experimental mice hoping that, as in humans, the immature cells would home in on the thymus, develop into mature T-lymphocytes, and circulate to the lymph nodes. Two weeks after the transplant, the mice could withstand Pneumocystis pneumonia. They had apparently acquired an immune system—and, experiments showed, it was an immune system of human cells. The researchers even located antibody-producing B-lymphocytes in their prized mice. The second team, working independently, successfully transplanted white blood cells from adult tissues into SCID mice. They demonstrated the animals' immune functions by injecting tetanus toxoid into the animals and showing that the mice could produce antibodie |
