In what may giver rise to improved diagnostic tests and treatments for allergy, a team of Penn State University researchers has for the first time shown that lipid molecules in cell membrane are key to mammals' reactions to allergens in a living cell.
researchers studied clusters of cholesterol-rich lipid molecules that are
believed to serve as platforms for the receptors that receive antibodies, the
proteins that protect the body from allergens.
examined IgE antibodies that, upon binding to their receptors, initiate a
cell's release of histamine — the substance that causes the unpleasant but
beneficial mucous production, congestion, and itchiness associated with
research is basically the molecular foundation for why many people sneeze in
the spring," said Ahmed Heikal, an associate professor in the Department
of Bioengineering and a leader of the project.
the idea that lipid molecules are linked to allergic response is not new, the
Penn State team is the first to document this connection in a living cell under
one has observed the domains in action because they are too small and too
transient--held together by very weak molecular interactions--to be viewed with
a light microscope," said Erin Sheets, a Penn State assistant professor of
chemistry who also is a leader of the project.
added: "To overcome this challenge, we used a combination of imaging and
spectroscopy techniques that we are developing in our laboratories."
study, the researchers first labelled the cell membrane and IgE antibodies with
two different fluorescent tags, and then introduced an allergen that bound to
receptors on the cell membrane, thus initiating an allergic response.
researchers took advantage of a property of fluorescence called fluorescence
lifetime, in which molecules are excited with very short laser pulses, to show
that the activity was taking place within the lipid domain.
that the results of their study "show that lipid domains in the cell membrane
associate with IgE antibodies and their receptors in the initial stages of an
The study has been reported in the Journal of