Eosinophil-particle interactions: A model system for study of cellular adherence and activation

In its role as an effector capable of killing large multicellular parasites, the eosinophil must be especially adapted for dealing with noningestible surfaces. A model system of Sepharose beads coated with serum protein or concanavalin A (Con A) has been used to study interactions between guinea pig peritoneal exudate eosinophils and noningestible particles. A small percentage of eosinophils were adherent to serum treated Sepharose; however, many cells were adherent to Con A-Sepharose. Adherence to Con A-Sepharose was decreased by pretreatment with 1 mM α-methylmannoside (α-MM). As compared to resting eosinophils, incubation of eosinophils with serum-treated Sepharose led to activation of oxidative metabolism as indicated by an eight-fold increase in superoxide anion production and an approximately threefold increase in quantitative leukocyte iodination. Eosinophils which were adherent to Con A beads could not be activated by either phorbol myristate acetate (PMA) or preopsonized zymosan. However, if adherence was reduced by preincubation with α-MM, PMA was able to activate the eosinophils. Neither soluble Con A nor Sepharose beads interfered with the assay of superoxide anion. These studies demonstrate the utility of Sepharose beads for studying interactions between eosinophils and noningestible particles.