Conference 7.286::space

711.0. "Space flight selectively depresses immune system" by PRAGMA::GRIFFIN (Dave Griffin) Mon Feb 25 1991 18:28

From: [email protected]
Date: 22 Feb 91 18:35:07 GMT


	UNIVERSITY PARK, Pa. (UPI) -- Exposure to near weightlessness in space
has differing effects on T-cells, depending on the cells' location in
the body, a team of researchers from Penn State University and the
Soviet Union said Friday.
	T-cells are the white blood cells that are the immune system's 
``search and destroyers.''
	European researchers had previously reported that space travel
decreased one aspect of human immunity because microgravity depressed
the rate at which T-cells taken from astronauts' blood multiplied.
	But a Penn State-Soviet team did not find a similar effect in T-cells
taken from the lymph nodes of five rats flown for two weeks aboard the
Soviet Biosatellite Cosmos 2044 mission.
	The Penn State-Soviet study was the first to examine microgravity
effects on the immune system using lymph nodes. The results have been
submitted for publication in the Journal of Applied Physiology.
	Andrea Mastro, a Penn State professor of microbiology and cell
biology, found that less than 1 percent of the T-cells circulate in the
blood. Most T-cells reside in the lymph nodes and spleen.
	A team of Soviet researchers examined spleens from Cosmos 2044 rats
and found effects similar to those found in T-cells taken from human
blood.
	Mastro believes that all of the blood, spleen and lymph node data
taken together indicate that microgravity has an effect on the immune
system. But ``there's no answer yet to the question of how far reaching
that effect is, or how important it would be in the very stressful
situation that spaceflight represents,'' she said.
	Mastro said the difference observed in tissue-based cells versus
those circulating in the blood could signal the ability of the immune
system to adapt to spaceflight.
	``It could mean that if we had looked at the lymph nodes after a
shorter period of exposure to microgravity, we would have seen an
effect,'' she said.
	Mastro is associate director of Penn State's Center for Cell
Research, a NASA Center for the Commercial Development of Space.
	She said that eventually the immune system's response to microgravity
might be used as a model for aging and the lowered immunity suffered by
some cancer patients or those with AIDS.
	``As people age, aspects of their immune response decrease very much
like the effects seen in space,'' Mastro said. ``Some of the other
effects of space, including bone loss and muscle atrophy, are also very
similar to aging. So we may be able to think of space as a way to get a
'fast peek' at aging.''