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LTB4, a potent chemotactic factor for purified guinea-pig eosinophils: interference of PAF-acether antagonists
E Coëffier1, D Joseph, B B Vargaftig
1Unité de Pharmacologie Cellulaire, Unité Associée Institut Pasteur-INSERM No. 285, Paris, France.
Abstract:
Two populations of eosinophils were separated upon a discontinuous metrizamide gradient from peritoneal lavages of polymyxin B-treated guinea-pigs. One population was of low density (between 20 and 22% of metrizamide, purity: 63 +/- 3%, n = 27) and another of normal density (between 22 and 24% of metrizamide, purity: 87 +/- 2%, n = 26). Responses to chemotactic stimuli were studied using a micro-Boyden chamber, results being expressed as the chemotactic index (CI, mean +/- S.E.M.), i.e. the ratio between the number of eosinophils migrating at 40 microns through a cellulose nitrate filter in the presence of the agonist and the number of cells migrating in the presence of the solvent alone. The normal density eosinophils responded more to LTB4 (CI = 19.4 +/- 4.6 with LTB4 10(-8) M; P less than 0.05; n = 9) than to PAF-acether (CI = 6.2 +/- 1.4 with PAF-acether 10(-8) M; P less than 0.05; n = 20). By contrast, low density eosinophils responded less intensely to LTB4 (CI = 7.6 +/- 1.8 with LTB4 10(-8) M; P less than 0.01; n = 6) and to PAF-acether (CI = 2.4 +/- 0.4 with PAF-acether 10(-8) M; P less than 0.05; n = 14). Guinea-pig eosinophils failed to migrate in response to FMLP and lyso PAF-acether.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Two guinea-pig eosinophil populations, differing in density, exhibit distinct migratory responses to chemotactic stimuli. Normal density eosinophils show greater chemotaxis to leukotriene B4 (LTB4) than to platelet-activating factor (PAF-acether), while low density eosinophils respond less to both.
Area of Science:
- Immunology
- Cell Biology
Background:
- Eosinophils play a role in inflammatory responses.
- Density heterogeneity of eosinophils suggests functional differences.
Purpose of the Study:
- To investigate the differential chemotactic responses of distinct eosinophil populations from guinea pigs.
- To compare the migratory behavior of low-density and normal-density eosinophils towards specific chemoattractants.
Main Methods:
- Separation of eosinophils into low-density and normal-density populations using a metrizamide gradient.
- Assessment of eosinophil migration using a micro-Boyden chamber assay.
- Quantification of chemotactic response using the chemotactic index (CI) towards LTB4 and PAF-acether.
Main Results:
- Normal-density eosinophils exhibited a significantly higher chemotactic index for LTB4 (19.4 +/- 4.6) compared to PAF-acether (6.2 +/- 1.4).
- Low-density eosinophils displayed reduced chemotaxis to both LTB4 (7.6 +/- 1.8) and PAF-acether (2.4 +/- 0.4).
- Neither eosinophil population migrated in response to FMLP or lyso PAF-acether.
Conclusions:
- Eosinophil density is a key determinant of their migratory responsiveness to chemoattractants like LTB4 and PAF-acether.
- Functional heterogeneity exists within guinea-pig eosinophil populations, impacting their role in inflammatory processes.