Interaction forces between red cells agglutinated by antibody. II. Measurement of hydrodynamic force of breakup

Abstract

The expressions derived in the previous paper for the respective normal, F3, and shear forces, Fshear, acting along and perpendicular to the axis of a doublet of rigid spheres, were used to determine the hydrodynamic forces required to separate two red cell spheres of antigenic type B crosslinked by the corresponding antibody. Cells were sphered and swollen in isotonic buffered glycerol containing 8 X 10(-5) M sodium dodecyl sulfate, fixed in 0.085% glutaraldehyde, and suspended in aqueous glycerol (viscosity: 15-34 mPa s), containing 0.15 M NaCl and anti-B antibody from human hyperimmune antiserum at concentrations from 0.73 to 3.56 vol%. After incubating and mixing for 12 h, doublets were observed through a microscope flowing in a 178-micron tube by gravity feed between two reservoirs. Using a traveling microtube apparatus, the doublets were tracked in a constantly accelerating flow and the translational and rotational motions were recorded on videotape until breakup occurred. From a frame by frame replay of the tape, the radial position, velocity and orientation of the doublet were obtained and the normal and shear forces of separation at breakup computed. Both forces increased significantly with increasing antiserum concentration, the mean values of F3 increasing from 0.060 to 0.197 nN, and Fshear from 0.023 to 0.072 nN. There was no significant effect of glycerol viscosity on the forces of separation. It was not possible to determine whether the shear or normal force was responsible for doublet separation. Measurements of the mean dimensionless period of rotation, TG, of doublets in suspensions containing 0.73 and 2.40% antiserum undergoing steady flow were also made to test whether the spheres were rigidly linked or capable of some independent rotation. A fairly narrow distribution in TG about the value 15.64, predicted for rigidly-linked doublets, was obtained at both antiserum concentrations.

Lu-ECAM-1-mediated adhesion of melanoma cells to endothelium under conditions of flow

“…Hence, the fluid forces present in our system range from 35 pN at 0.32 dynes/cm2 to 110 pN at 1.0 dynes/cmz. Since this range of forces is consistent with the estimated strength of a single receptor/ligand bond (<I00 pN; Tha et al, 1986;Evans et al, 1991), it seems possible that adhesion between a B16-FI0 melanoma cell and Lu-ECAM-1 is mediated by a single bond and that this single bond is not strong enough to mediate tumor cell arrest at high shear stresses in vitro.…”

Dissecting Individual Ligand–receptor Bonds With a Laminar Flow Chamber

“…These arrests could be ascribed to well defined interactions between endothelial E-selectin and leukocyte ligand since they were inhibited by specific antibodies. In view of previous theoretical [26] and experimental [24,27] work, it was assumed that a single molecular bond could mediate cell arrest. Analysing the statistics of arrest duration, it was concluded that the dissociation rate of an Eselectin mediated bond was about 0.5 s −1 .…”

Stanley Mason: His contribution to the science of Biorheology

“…Accordingly, experiments were carried out using swollen, sphered and glutaraldehyde-fixed red cells of antigenic type B suspended in aqueous glycerol containing 0.15 M NaCI and known amounts of anti B-antibody (61). Doublets of cells formed by two-body collisions at very low shear stresses were observed as they entered the flow tube, and then tracked in the traveling microtube apparatus in a steadily accelerating Poiseuille flow until break-up.…”