Reactivation of tritonated models of human polymorphonuclear leukocytes (PMNs): a computer-assisted analysis

The orientation (chemotaxis) and locomotion (chemokinesis) of human polymorphonuclear leukocytes (PMNs) are generated by an internal movement mechanism that involves active cytoplasmic movement; they are influenced by external environmental and ionic conditions. We have studied the degree to which the orientation and movement mechanisms of PMNs are self-contained within the cell and the degree to which they are under membrane control. PMNs were partially and selectively demembranated by treatment with the non-ionic detergent, octyl-phenoxyl-polyethoxyethanol (commercially known as Triton X-100) under controlled conditions. The tritonated PMNs (referred to in the literature as models) were non-motile and non-locomotory. Addition of ATP/Mg++ with a trace amount of Ca++ to the medium was followed by reactivation of the tritonated PMN models to move again as motile cells. Although these reactivated PMN models actively locomoted, they could no longer orient to chemoattractants. Thus, the reactivation process restored the physical self-contained movement parameters but could not reestablish the orientation capacity (chemotactic responsiveness) that was characteristic of live PMNs. The demembranation process apparently destroyed the chemotactic receptors and/or eradicated the coordination function of the membrane. Videotapes of normal (control) as well as reactivated PMN movement were analyzed for movement characteristics. These characteristics were objectively analyzed with a newly designed computer-assisted micro-image-processing technique whereby the videotapes were digitized and quantified and the actual PMN movement printed out in computer-graphics and tracings (Freeman codes) for confirmation of orientation and movement arising as a result of reactivation.