Abstract Previous studies of human basophil mediator release have noted that the bacterial peptide fmet-leu-phe and the anaphylatoxin C5a induce comparable levels of histamine release while only fmet peptide induces leukotriene release. Since 5-lipoxygenase metabolism of arachidonic acid is calcium dependent, we examined the characteristics of the human basophil [Ca++]i response which follows its activation by either fmet peptide or C5a. While the peak [Ca++]i response was essentially identical for these two stimuli, fmet peptide induced a prolonged increase in [Ca++]i while C5a stimulated only a transient increase in [Ca++]i that was essentially over within 2 minutes of adding the stimulus. Simultaneous addition of EDTA with fmet peptide revealed the two phases of the [Ca++]i response and demonstrated that leukotriene release was dependent on an elevated [Ca++]i level in the 2–5 minutes following challenge. Enhancement of leukotriene release induced by C5a by agents such as staurosporine and interieukin-3 also produced a [Ca++]i kinetic curve which resembled fmet piptide. Single cell studies of the [Ca++]i response could detect no subpopulations of cells which responded preferentially to fmet peptide or C5a, eliminating the possibility that the ability of fmet peptide to induce leukotriene was a result of its action on a functionally distinct population of basophils.

MacGlashan, D., & Warner, J. (1991). Stimulus-Dependent Leukotriene Release From Human Basophils: A Comparative Study of C5a and Fmet-leu-phe. Journal of Leukocyte Biology, 49(1), 29–40.