Stimulus-dependent leukotriene release from human basophils: a comparative study of C5a and Fmet-leu-phe.
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 interleukin-3 also produced a [Ca++]i kinetic curve which resembled fmet peptide. 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
D
Johns Hopkins Asthma and Allergy Center, Division of Clinical Immunology, Baltimore, Maryland 21224.
Warner
J
J
D000470:Alkaloids / Q000494:pharmacology; D001491:Basophils / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000032:analysis / Q000378:metabolism; D015936:Complement C5a / Q000494:pharmacology*; D004492:Edetic Acid / Q000494:pharmacology; D006801:Humans; D015289:Leukotrienes / Q000378:metabolism*; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology*; D019311:Staurosporine
D000470:Alkaloids; D015289:Leukotrienes; D009240:N-Formylmethionine Leucyl-Phenylalanine; D015936:Complement C5a; D004492:Edetic Acid; D019311:Staurosporine; D002118:Calcium