In vitro effect of R 17934, a new drug with antitubulin activity, on neutrophil granulocyte locomotion and orientation.

R 17934 is a new synthetic antimicrotubule drug, which binds to tubulin at the same site as does colchicine. The interaction of this drug with human neutrophil granulocyte locomotion and orientation was examined, using a modified reversible Boyden chamber and a gradient chamber offering a direct visual assay of cell orientation. R 17934 at concentrations as low as 5 x 10(-6) M was found to inhibit chemokinesis to an equal degree in gradient chambers, and in Boyden chambers using checkerboard experiments, in which the absolute concentrations and the concentration gradients of the chemotactic agent were varied. At higher concentrations (10(-5) M) R 17934 also inhibited chemotaxis in Boyden chambers. Much lower concentrations of R 17934 (10(-7) M) were found to affect the ability of neutrophils to orient in gradient chambers. This finding may show that filters form a more suitable substrate for oriented pseudopod formation of microtubule-deficient cells than do glass or plastic slides. In conclusion this study has provided evidence that in the absence of functioning microtubules neutrophils can still orient and migrate directionally towards the source of a concentration gradient, but that they do so less precisely. The finding that R 17934 inhibited chemokinesis suggests that this drug may interfere with the mechanism translating a recognition signal into locomotion. The previous finding that colchicine also had this effect supports the hypothesis that this process may be microtubule-dependent.