A specific radioreceptor assay for leukotriene C4 and the measurement of calcium ionophore-induced leukotriene C4 production from human leukocytes.
A highly specific radioreceptor assay (RRA) for leukotriene (LT) C4 using BC3H-1 cell membrane as a source of LTC4 receptors was developed and demonstrated its use in the measurement of calcium ionophore A23187-induced LTC4 production from purified eosinophils, neutrophils, and mononuclear cells. Unlabeled LTC4 competed for the specific [3H]LTC4 binding to the BC3H-1 cell membranes in a dose-dependent manner. Under the experimental conditions used in this study, the calculated IC50 value of unlabeled LTC4 was 27.2 +/- 1.2 nM (n = 5). The sensitivity of the method for LTC4 was 0.6 pmol. The cross-reactivities of LTD4, LTE4, and FPL 55712 were negligible. The recovery of the exogenously added LTC4 with eosinophils was greater than 90% in both the presence and the absence of calcium ionophore A23187. Calcium ionophore induced 73.0 +/- 17.0 ng of LTC4 production/10(6) eosinophils (n = 8), and this was about 20-40 times more than those from neutrophils and from mononuclear cells.
Tamura
N
N
Department of Medicine, Creighton University School of Medicine, Omaha, NE 68178.
Agrawal
D K
DK
Townley
R G
RG
D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D004804:Eosinophils / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D007476:Ionophores / Q000494:pharmacology*; D007962:Leukocytes / Q000378:metabolism*; D011869:Radioligand Assay; D013189:SRS-A / Q000032:analysis* / Q000096:biosynthesis
D007476:Ionophores; D013189:SRS-A; D002118:Calcium