Kinetics of linear rouleaux formation studied by visual monitoring of red cell dynamic organization

Red blood cells (RBCs) in the presence of plasma proteins or other macromol ecules may form aggregates, normally in rouleaux formations, which are disp ersed with increasing blood flow. Experimental observations have suggested that the spontaneous aggregation process involves the formation of linear r ouleaux (FLR) followed by formation of branched rouleaux networks. Theoreti cal models for the spontaneous rouleaux formation were formulated, taking i nto consideration that FLR may involve both "polymerization," i.e., interac tion between two single RBCs (e + e) and the addition of a single RBC to th e end of an existing rouleau (e + r), as well as "condensation" between two rouleaux by end-to-end addition (r + r). The present study was undertaken to experimentally examine the theoretical models and their assumptions, by visual monitoring of the spontaneous FLR (from singly dispersed RBC) in pla sma, in a narrow gap flow chamber. The results validate the theoretical mod el, showing that FLR involves both polymerization and condensation, and tha t the kinetic constants for the above three types of intercellular interact ions are the same, i.e., k(ee) = k(er) = k(rr) = k, and for all tested hema tocrits (0.625-6%) k < 0.13 +/- 0.03 s(-1).