Modulation of eosinophil chemotaxis and eosinophil chemotactic factor release by concanavalin A.

Concanavalin A (Con A) is not a chemotactic factor for guinea pig eosinophil leukocytes. It does, however, modulate the response of cells to neutrophil-derived eosinophil chemotactic factor (ECF) or to C5a. This effect occurs by a direct interaction of Con A with the target cell and is reversible by appropriate doses of alpha-methyl-D-mannoside (alpha-MM). The inhibition of chemotaxis at high doses of Con A is due to agglutination of the cells on top of the filter. The mechanism of enhancement at low doses is not understood, but several possible explanations are explored. Careful definition of the effect of Con A on eosinophil chemotaxis makes it possible to exclude an effect of Con A on ECF secretion by neutrophils.