ROANOKE TIMES
Copyright (c) 1996, Roanoke Times
DATE: Friday, March 22, 1996 TAG: 9603220084
SECTION: NATL/INTL PAGE: A-1 EDITION: METRO
DATELINE: WASHINGTON
SOURCE: Associated Press
New research disputes a long-held conclusion about how the immune system works and suggests that childhood vaccinations may be effective when started within days of birth.
This challenges a conclusion that has been fundamental in biology for decades. Two scientists, F. Macfarlane Burnet of Australia and Peter B. Medawar of Britain, shared the Nobel Prize in 1960 for research showing that the immune system of newborns was too immature to reject foreign antigens.
The new work creates a fresh, fundamental understanding of the immune system, but scientists said it will take years before the laboratory studies on mice could be translated into medical treatment for humans.
Reports on the findings will be published today in the journal Science.
Marcella Sarzotti-Kelsoe of the Baltimore Veterans Affairs Medical Center led a team that inoculated 2-day-old mice with low doses of virus and found the animals developed long-term immunity to the disease.
However, she said, newborn mice exposed to large doses of the same virus were not able to mount an immune response and quickly died.
It shows, she said, that ``Given the correct dose, newborns can respond like adults.''
If the new findings lead to an earlier start of immunizations, said Sarzotti-Kelsoe, it would narrow the period of time that children are vulnerable to infectious diseases.
She noted, for example, that pneumococcal pneumonia vaccine cannot be given now until the age of 2 because it doesn't work. Vaccinations for measles, mumps and rubella are not given until the age of 15 months, although the diseases can be contracted at an earlier age.
At Case Western Reserve University, a team led by Paul V. Lehmann, examined the reaction of newborn mice to antigens mixed with two types of oils, called adjuvants, which are used in laboratory experiments to excite the immune system.
Lehmann said that mice injected with an oil that included antigen and dead bacteria developed what he called a Th1 reaction. This causes inflammation and can destroy tissue. This type of reaction can cause diabetes, arthritis and other diseases where the immune system attacks its own body tissue.
However, newborn mice injected with an adjuvant that included only the antigen, Lehmann said, developed a Th2 reaction, which is not inflammatory and is able to protect from disease.
``This shows that neonates are fully immune competent,'' said Lehmann, referring to newborns. He said the findings should force ``a reinterpretation'' of the Burnet-Medawar studies.
Other scientists hailed the achievement of the three groups of researchers.
``This is terribly important,'' Kevin Lafferty of the John Curtin School of Medical Research in Canberra, Australia, told Science.
``These experiments clearly show that there is nothing special about the neonatal period,'' Alfred Singer of the National Cancer Institute said in Science. ``That's an important correction.''
Sarzotti-Kelsoe said the new work gives clues of how vaccine formulas could be designed to allow babies to start childhood inoculations shortly after birth.
Lehmann said the findings may be a key to developing drugs to control arthritis and diabetes, and may help in developing vaccines against complex viruses, such as HIV.
``We may learn how to induce a specific protective response'' that would prevent those diseases, he said.
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