Functional alterations in the membrane of motile polymorphonuclear leukocytes

We have applied microdocumentary techniques to the study of movement of human PMN's and their behavioral response to a chemoattractant. We discuss here findings which suggest a different interpretation from currently accepted theory. Videotape recordings were made on the movement of human PMN's. A slide modified from previous descriptions was designed to predict a straight-line gradient which could be maintained for periods up to 60 minutes. PMN suspensions were placed on the bridge of the slide with the chemoattractant N-formylmethionylleucyl-phenylalanine (F-Met-Leu-Phe) placed in one wall and PMN suspension medium in the well on the other side of the bridge. Videotapes were traced on the monitor screen at 15-second intervals. A lack of consistent orientation and "head-tail" polarity of any individual PMN was observed. Apparent polarity was observed less than 10% of the time. The net movement of cells in a given field was always toward the direction of the approaching and maintained gradient, but any individual cell failed to show a sustained directional orientation or movement toward the gradient. Individual cells constantly reoriented. Analysis of time-dependent characteristics of the chemotactic response is essential to the ultimate understanding of PMN motility.