Allergic response tied to lipid molecules in cel...(itiating an allergic response. But t...),Health

But to demonstrate that this activity was taking place within the lipid domain, the researchers had to take advantage of a property of fluorescence, called fluorescence lifetime, in which molecules are excited with very short laser pulses. The length of time a molecule remains in its excited state before emitting a photon--the fluorescence lifetime--provides unique information about the fluorescently-labeled molecule's environment and its chemical structure. For example, a particular molecule might relax to its lowest-energy state quickly or slowly depending on whether it is exposed to a solvent.

"We previously showed that our fluorescently-labeled membrane probe has a longer lifetime within a cholesterol-rich lipid domain," said Sheets. "Here we show that changes in this lifetime follow the changes that occur during the first steps in the allergic response process. Our results also show that lipid domains in the cell membrane associate with IgE antibodies and their receptors in the initial stages of an allergic reaction."

In the future, Sheets and Heikal plan to apply the team's discoveries to a project involving aging. During the aging process, T cells, which protect the body from foreign substances like viruses and cancer cells, can lose their ability to signal effectively. Sheets and Heikal plan to use these fluorescence-lifetime imaging tools to examine the structure and integrity of T-cell membranes with a goal of determining why they lose their knack for signalling and how this problem can be corrected.

"We want to compare the effectiveness of signaling in young T cells, which clear out debris quickly, to old T cells, which are not as efficient," said Sheets. "I think it will be a pretty cool application of our technique."

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