Computer tracking of white blood cells on protein-coated surfaces

The kinetics of human white blood cell adhesion and detachment is of interest in evaluating the effects of synthetic materials for blood damage. In an experimental setup, a suspension of fluorescently labeled white blood cells and unlabeled red blood cells is drawn through a protein-coated glass tube at a constant flow rate. Interaction of the white cells with the inside surface of the tube is monitored using a microscope coupled to an SIT television camera. A videotape recorder provides a permanent record on 1/2 in videotape to permit subsequent measurement of cell dynamics through the field of view. Instrumentation based on an image digitizer and a Zenith PC has been developed to automate the visual analysis of the videotapes. The new system tracks the cell motion on a frame-by-frame basis; once initiated, the entire process is controlled by the computer. Measurements include the number and nature of cell-to-surface collisions, residence times (the duration of the collisions), average distances traveled, and the size of clusters. Conditions have been uncovered where for two cases, the net cellular adhesion is the same while the pathways to this result are different. The design of the system is described together with experimental results.