Leukotriene B4 receptors on guinea pig alveolar eosinophils
- Department of Pharmacology, Faculty of Medicine University of Sherbrooke, Quebec (Canada)
The existence of receptors for LTB4 on highly purified guinea pig alveolar eosinophils was investigated. Massive infiltration of eosinophils in alveolar spaces was induced in guinea pigs by i.v. injections of Sephadex beads G50 (16 mg/kg). Alveolar eosinophils (50 {times} 10(6) cells) were purified to approximately 98% by Percoll continuous density gradient centrifugation. The binding studies indicated that alveolar eosinophils bind LTB4 in a saturable, reversible and specific manner. Scatchard analysis indicated the existence of high-affinity binding sites (Kd1 = 1.00 {plus minus} 0.22 nM; Bmax1 = 966 {plus minus} 266 sites/cell) and low-affinity binding sites (Kd2 = 62.5 {plus minus} 8.9 nM; Bmax2 = 5557 {plus minus} 757 sites/cell). The metabolism of LTB4 by alveolar eosinophils in binding conditions was assessed by RP-HPLC and no significant degradation of (3H)LTB4 was observed. LTB4 dose-dependently stimulated eosinophil migration in both chemokinesis and chemotaxis assays with an EC50 value of 1.30 {plus minus} 0.14 and 18.14 {plus minus} 1.57 nM, respectively. LTB4 caused a dose-dependent increase in the production of superoxide anion with an apparent EC50 value of 50 {times} 10(-9) M in the authors experimental conditions. LTB4 also induced a dose-dependent increase in the generation of TxA2 with an EC50 value of 46.2 {times} 10(-9) M. Taken together, their results demonstrated that guinea pig alveolar eosinophils express two classes of specific receptors for LTB4. The high-affinity binding sites seem associated to chemokinesis and chemotaxis whereas the low-affinity binding sites seem associated to superoxide anion production and generation of TxA2. The existence of LTB4 receptors in eosinophils could explain the presence of these cells in hypersensitivity reactions.
- OSTI ID:
- 5044906
- Journal Information:
- Journal of Pharmacology and Experimental Therapeutics; (United States), Vol. 258:3; ISSN 0022-3565
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
EOSINOPHILS
BIOCHEMISTRY
PROSTAGLANDINS
RECEPTORS
BIOCHEMICAL REACTION KINETICS
DOSE-RESPONSE RELATIONSHIPS
GUINEA PIGS
LIQUID COLUMN CHROMATOGRAPHY
LUNGS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ULTRACENTRIFUGATION
ANIMALS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY
BODY FLUIDS
CENTRIFUGATION
CHEMISTRY
CHROMATOGRAPHY
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
KINETICS
LEUKOCYTES
MAMMALS
MATERIALS
MEMBRANE PROTEINS
ORGANIC COMPOUNDS
ORGANS
PROTEINS
REACTION KINETICS
RESPIRATORY SYSTEM
RODENTS
SEPARATION PROCESSES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques