Are there two functionally distinguished Neu5Gc pools with respect to rouleau formation on the bovine red blood cell?

Abstract

Bovine red blood cells (RBCs) do not exhibit any aggregation tendency in autologous plasma and, therefore, all bovine rouleaux obtained in vitro are regarded as artificial. The present study reports the bovine RBC rouleau formation by either bovine or human fibrinogen and Ca²⁺ ions. The phenomenon was induced through two‐step cell incubation: in 0.9% NaCl and 1% bovine albumin at 37°C for 30 min followed by 20 hrs incubation at 30°C in the fresh solution supplemented with 10 mM glucose. Its mechanism is unknown. During the incubation the number of N‐glycolylneuraminic acid molecules per cell decreased from 48.1 to 44.9 amoles, which accounted for 7%. The treatment of RBCs with V. cholerae sialidase under the same conditions resulted in a 94% drop in the Neu5Gc quantity and did not induce the rouleau formation in the same fibrinogen preparation. The preliminary results rise a question whether the bulk of sialic acid is required in the aggregation of bovine erythrocytes under static conditions. Only a minor pool of Neu5Gc seems to be responsible for suppression of the phenomenon.