Experiments on Rouleau Formation

Abstract

Rouleau formation was measured by an adaptation of an old method used by Ponder (1927, Q. J. Exp. Physiol. 16, 173–194). Blood was depleted of red cells to a low hematocrit. It was stirred under standardized conditions, and after various times, samples were examined by microscope. Mean rouleau length was taken as an index of rouleau formation. The method was used to observe changes of rouleau formation with time and temperature and with variations in erythrocyte sedimentation rate (E.S.R.). Under these experimental conditions, mean rouleau length increases with time up to 40 min. Over a range of hematocrit values between 0 and 4%, rouleau length is a linear function of hematocrit. At higher hematocrits random aggregations based on columnar units are seen. Rouleau formation is temperature dependent and maximum mean rouleau length occurs around 37 °C. Subjects with a high erythrocyte sedimentation rate tend to form long rouleaux. By exchanging red blood cells (R.B.C.) between two ABO Rh compatible patients with greatly differing E.S.R. and mean rouleau length, it was shown that the agent responsible was in the plasma and not on the R.B.C. The results were compared with a theory of aggregation which proved inadequate in some respects.