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Where the Antigens Are
by Richard Currey
A patient reported an allergic reaction after eating strawberries, yet came up negative on conventional skin testing. So the doctor tried something unconventional. He applied the juice of a fresh strawberry—as opposed to processed extracts—directly to the skin, and got the reaction his patient described.
HHMI investigator Daphne Preuss, a plant biologist, likes to share this story of her physician friend. "It tells us that we're missing something when it comes to allergies," she says. "We need greater diagnostic precision, and treatments that home in on the exact allergens involved in a reaction." Her work could make that happen. In collaboration with HHMI investigator Albert Bendelac, Preuss is identifying the molecular components of pollen cells that may hold the key to innovative detection and therapy for allergies.
Several years ago Preuss was investigating how female plant structures recognize a "fit" among the thousands of male pollen grains that arrive on the wind or are dropped by bees. In the process of identifying "recognition genes" that code for proteins on the outer surface of pollen cells, Preuss began to wonder if these extracellular surface proteins might also be involved in allergies.
If pollen's surface molecules have been overlooked as causative factors in allergies, it is largely because skin-testing extracts are "washed," a process that removes the outer coat. "Inadvertently, conventional preparations led to purification of mostly molecules inside the pollen cell," Preuss says. She arranged for her lab to receive unwashed batches of pollens. In the process of learning how to extract surface materials from many different pollen species, Preuss noted that pollen's outer coat carries many lipid compounds.
Enter Bendelac, an immunologist whose work has been instrumental in demonstrating that lipids are involved in inflammation, a biological phenomenon now understood to be a critical factor in such maladies as diabetes, heart disease—and asthma and allergies.
Illustration: Brian Cronin
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