A novel, specific, and potent biological action of leukotriene C4 (LTC4) was demonstrated in the Chinese hamster lung fibroblast cell line V79A03 (V79 cells), namely the conferment of protection against subsequent γ-irradiation. Consequently, studies were conducted to determine whether LTC4-conferred radioprotection could be attributed to a receptor-mediated phenomenon. Specific binding sites for leukotriene C4 (LTC4) were identified and characterized using intact V79 cells incubated at 4°C in the presence of serine-borate, during which time conversion of LTC4 to LTD4 or LTE4 was undetectable. Binding was maximal in a broad region between pH 6.2 and 8.8. Ca2+, Mg2+, and Na2+ were not required for binding, and binding was not altered by GTP, ATP, or cAMP, by leikotrienes C4, D4, or E4, or by the leokotriene end point antagonists LY 171883, FPL 55712, or Revlon 5901-5. Scatchard analyses and kinetic experiments indicated the presence of high-affinity [Kd = 2.5 ± 0.63 nM, approximately 9.9 × 105 sites/cell] and low-affinity [Kd = 350 ± 211 nM, approximately 2.7 × 106 sites/cell] binding sites. The observed binding characteristics of LTC4 to V79 cells are consistent with a receptor-mediated phenomenon. In a companion communication which follows this report, we report the subcellular distribution of LTC4, binding to V79 cells and demonstrate that this binding is unlikely to be attributed principally to interaction with glutathione-S-transferase.
|Number of pages||13|
|State||Published - Oct 1990|
Bibliographical noteFunding Information:
The authors gratefully acknowledge gifts of V79 cells from Dr. E. V. Holahan, leukotrienes from Dr. J. Rokach, prostaglandins from Dr. D. Morton, and leukotriene antagonists from Dr. A. Taub, Mr. W. Fields and Dr. T. P. Pruss. Valuable technical assistance was provided by C. Hollies. J. Koeser and M. Waldbillig provided skilled secretarial assistance. This work was supported by NIH HD20780, USUHS Protocol C08517, and Defense Nuclear Agency Work Unit #B2152. The views presented in this paper are those of the authors. No endorsement by the Defense Nuclear Agency or the Department of Defense has been given or should be inferred.
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