[A study of leukocyte chemotaxis in a glass micropipette]

Chemotaxis, the directional locomotion of a cell toward a source of a chemical gradient, is an important phenomenon occurring for mobilizing immune cells at sites of infection and injury. This phenomenon has been simulated in analyzing the movement in vitro of a chemoattracted cell inside a glass micropipette. A microneedle filled with fMLP, N-formyl-methionyl-leucyl-phenylalanine, at a concentration of 9.10(-7) M in 1% gelatin, is inserted in a glass micropipette containing Hanks buffer solution. After diffusion of fMLP in the glass micropipette until a constant gradient is established, the tip of the glass micropipette is moved near a polymorphonuclear neutrophil. Its spontaneous movement inside the micropipette towards the chemotactic source can be observed and quantified. Without any counter-pressure (positive pressure), the cell spontaneously advances with an average velocity of 0.14 +/- 0.04 micron/s. Corresponding to the maximal strength developed by the cell during its motion, the required strength to stop the chemotactic migration has been estimated to be 39 +/- 4 nN. Giving both qualitative and quantitative information on the dynamics of cell motility, this experiment will be helpful in the understanding of some aspects of cell motility in the tissues.