LTB4, a potent chemotactic factor for purified guinea-pig eosinophils: interference of PAF-acether antagonists.

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)