Induction of the oxidative response and of concanavalin A-binding capacity in maturing human U937 cells.

Differentiation of U937 cells with phorbol myristate acetate (PMA) induces high stimulation by concanavalin A of the respiratory burst as well as an increase in concanavalin A-binding cell capacity. New concanavalin A-binding proteins are detected as differentiated U937 cells acquire their capacity to be activated by concanavalin A. We identified several concanavalin A-binding proteins, of molecular mass 30-200 kDa, in PMA-differentiated cells, but only some of them seem to be directly related to the concanavalin A effect on the respiratory burst. One of these candidates could be a glycoprotein with an apparent molecular mass of 140 kDa which behaved as a major concanavalin A-binding protein and is expressed on differentiated cells at the time these cells respond maximally to concanavalin A.