Medicine: Progress in Transplants

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It is being pressed with unusual vigor at Stanford University. There, Radiologist Henry S. Kaplan is experimenting in animals with massive doses of cortisone-type steroids, which cut down the body's output of lymphocytes (the most aggressive type of white cells against foreign tissue) but do not knock out most other types of blood cells. "The hope," says Dr. Kaplan, "is that the lymphocyte system, recovering in the presence of the graft, may learn to live with it."

Across the courtyard in Stanford's department of genetics, other researchers are looking for answers at the submicroscopic level, inside the white cells themselves. Dr. Gustav Nossal is exploring the fundamental question of why nature evolved the rejection mechanism in the first place. Likeliest explanation: as a protection against infection by viruses and bacteria. The body actually develops two such defenses. It makes 1) antibodies, which circulate in the blood in the gamma globulin fraction (these can be transferred from person to person, hence the use of gamma globulin in measles and some other viral diseases), and 2) lymphocytes, which migrate rapidly to the site of invasion by foreign material, and launch a counterattack. But how?

The nub of the matter seems to be the nucleus of the lymphocyte cell. This contains chromosomes, the dictators of heredity, which in turn contain big molecules of nucleic acids. One type is ribonucleic acid (RNA), which shows up in tiny particles called ribosomes. They consist of a core of RNA wrapped in a coating of protein. The RNA contains a code of orders that dictate what proteins the body will tolerate.

This mechanism, says Dr. Nossal, may be nothing more than the body's primary defense against abnormal cells that appear in it by mutation. Unchecked, they might become cancer. The healthy body destroys such aberrant cells, probably every day. Dr. Kaplan theorizes that in Hodgkin's disease the abnormal cells treat the body's normal cells as foreign invaders, and in effect turn them out of their own house. A key finding from Manhattan's SloanKettering Institute bridges hitherto far-apart fields: advanced cancer patients, whose rejection mechanism has undergone a serious breakdown, will accept skin grafts not only from unrelated donors, but even from other species, e.g., pigskin.

From Monkeys to Men. At U.C.L.A.'s new medical center in Westwood, a research team headed by Surgeon Franklin L. Ashley has tried to make the ideal chemical switch by taking lymphocytes and breaking them down to get almost pure RNA. The researchers take both lymphocytes and grafts from one group of rats. If the concentrated RNA is injected into other rats before they receive grafts from the same donors, 25% of the animals will take the grafts permanently. The researchers expect to push the percentage higher when they get the best dosage figured out. After working up through monkeys, they hope to find ways of testing the technique in man within a year. This, like similar work in England, raises the inviting possibility of injecting a newborn child with RNA from a relative who can then serve him as a future donor of skin or organs.