October 22, 1999--Researchers have illuminated a crucial step in the immune system's response to infection by using live cell imaging to follow the movement of immune system cells that have been genetically manipulated to produce a fluorescent jellyfish protein.

The north Pacific jellyfish Aequoria victoria is thought to startle predators by emitting a bioluminescent glow using the green fluorescent protein (GFP). Molecular biologists have used GFP to their own advantage by splicing the gene for GFP into the genes of a number of proteins, thereby creating luminous proteins that are easily observed in living cells.

In recent years, researchers have used GFP to study a variety of cellular processes, including cell division in yeast and development of the nervous system in worms. Now HHMI associate Brian Schaefer and colleague Colin Monks, who are both at the National Jewish Medical and Research Center in Colorado, have used GFP and live cell imaging techniques to probe how T cells respond to infection.

The research team, which also included HHMI investigators Philippa Marrack and John Kappler and National Jewish investigator Gary Johnson, published their findings in the October 22, 1999, issue of the journal Immunity.

Monks and Johnson had been studying signal transduction in the facilitator cells of the immune system--so-called helper T cells. When helper T cells encounter foreign molecules, they kick the immune system into gear, alerting it to the presence of invaders and prompting the production of the appropriate antibodies.

But T cells don't find antigens on their own--the foreign molecules must be proffered by antigen-presenting cells (APCs), which recognize invaders, chew them up, and display parts of the destroyed enemy on their outer surface.

When an APC displaying antigen
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Contact: Jim Keeley
keeleyj@hhmi.org
301-215-8858
Howard Hughes Medical Institute
21-Oct-1999