The story of an altered-gene experiment at the National Institutes of Health gave heart to many people, but it also demonstrated a critical need. In the first of what will surely become a flood of attempts to repair genetic deficiencies, NIH doctors recently dosed a four-year-old girl suffering a rare immune deficiency with samples of her own white blood cells, altered to produce a critical protein. Now they wait and watch, planning new infusions monthly, hoping the damage to her immune system can be corrected.
The girl suffers from adenosine deaminase deficiency, similar to the ailment that kept a Texas boy confined to a plastic chamber all his life. It's caused by a lack of the gene that makes the adenosine deaminase (ADA) enzyme, needed to clear the blood of dangerous metabolic byproducts that destroy immune cells. Knowing the location of the deficient gene, NIH researchers R. Michael Blaese, W. French Anderson and Kenneth Culver decided to try a repair job.
The doctors removed some of the girl's blood and separated out the T cells, key immune system components. Using recombinant DNA techniques, they inserted a copy of the human ADA gene into a virus specially weakened to prevent disease. Next, they infected the T cells with the virus and grew large quantities of the cells. Tests showed that some of the cells began producing the ADA enzyme, so the scientists moved to the next step: infusion back into the girl's blood. They hope the altered T cells will survive, producing ADA and allowing a bloom of other types of immune cells.