Suspensions of caseinate-elicited guinea pig PMNs actively and specifically deplete endogenous LTB4. The depletion is initiated with and exceeds the biosynthesis of LTB4. The depletion is inhibitable by NaCN. Human and rat PMN also show a similar depletion of endogenous LTB4; but unlike the guinea pig PMN, exogenous LTB4 is rapidly oxygenated to the omega hydroxy- and carboxy-LTB4 by mechanisms unaffected by cyanide. Depletion of endogenous LTB4 in the guinea pig PMN cannot be accounted for by specific reacylation into the phospholipid nor by the recently described enzymes capable of reducing the leukotriene triene. That the myeloperoxidase may be responsible for the depletion of LTB4 has not been eliminated and is suspected due to the cyanide inhibitable nature of this phenomenon. Such a mechanism would require a novel utilization of an activated species of oxygen by an enzyme or nonenzymatic protein surface.

No abstract