Positive correlation between superoxide release and intracellular adenosine deaminase activity during macrophage membrane perturbation regardless of nature or magnitude of stimulus

Summary

Tuftsin stimulates macrophages to release superoxide in direct proportion to intracellular adenosine deaminase activity over a concentration range of 125 to 625 nM tuftsin. This relation is comparable to that previously observed for stimulation by single concentration of several agents. This finding led to the conclusion that the relation between superoxide and adenosine deaminase is independent of the nature or magnitude of the stimulus. In absolute terms, tuftsin increases superoxide secretion up to 375 nM tuftsin; further increases in tuftsin concentration cause a rapid decrease in superoxide secretion to near base line at 500 nM tuftsin. In contrast, the phagocytic response to tuftsin remains maximal up to 10 μM with no indication of inhibition at higher concentrations. Thus, tuftsin stimulation of phagocytosis and superoxide release may be at least partially independent phenomena.