Inhibition of neutrophil and eosinophil chemotactic responses to PAF by the PAF-antagonists WEB-2086, L-652,731, and SRI-63441.

The influence of the three PAF-antagonists WEB-2086, L-652,731, and SRI-63441 on the chemotactic response of neutrophil and eosinophil granulocytes to PAF was investigated. When the PAF-antagonists were added to the cell suspension that was exposed to a gradient of PAF, WEB-2086 and SRI-63441 at the concentration of 10(-6) mol/litre inhibited (P less than .01) the neutrophil and eosinophil chemotactic response to 10(-8) and 10(-9) mol PAF per litre; at the concentration of 5 x 10(-6) mol/litre, WEB-2086 and SRI-63441 also inhibited (P less than .02) the response to 10(-7) mol PAF per litre. Under the same conditions L-652,731 at the concentration of 5 x 10(-6) mol/litre inhibited (P less than .01) the eosinophil chemotactic response to 10(-8) and 10(-9) mol PAF per litre. The inhibition of the chemotactic response to PAF by the three PAF-antagonists was specific, since the chemotactic response to C5f, f-MLP, and LTB4 was not affected by WEB-2086, L-652,731, or SRI-63441, neither was the chemokinetic migration induced by albumin.