Fundamental Studies on the Mechanism of Erythrocyte Aggregation and the Inhibition

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The velocity of erythrocyte aggregation induced by various macromolecules was measured with a shear rate- and temperature-controlled rheoscope combined witha video-camera, an image analyzer and a computer.1. Effect of physicochemical environments: (1) With increasing pH, the velocity increased. The aggregates at alkaline pH were stable for shear stress. (2) With increasing temperature, the velocity increased. But the aggregation in plasma was accelerated below 15゜C. The aggregates by fibrinogen and Ig G were morphologically different.(3)With increasing osmolarity, the velocity increased, but decreased above 400 mOsm.2. High molecular weight macromolecules were more effective for the erythrocyte aggregation than low molecular weight macromolecules were more effective for the erythrocyte aggregation than low molecular weight macromolecules. However, the effective concentration was different among the molecular species.3. Ig G-induced erythrocyte aggregation was inhibited by albumin, whil … More e fibrinogeninduced one was accelerated by albumin.4. The erythrocyte-binding site in fibrinogen molecule for leading to erythrocyte aggregates was deduced to be mainly in residue No. 207-303 of A<alpha> chain and partly in residue No. 375-411 of <gamma> chain.5. The effectiveness of fibrinogen degradation products (by plasmin) for the erythrocyte aggregation was in the order, fibrinogen > fragment X > fragment Y (fragments D and E did not form aggregates).6. An evidence for the specific binding site of bridging macromolecules on the erythrocyte surface was obtained for dextran- and polyglutamic acid-induced erythrocyte aggregation.7. Glycoproteins in addition to sialic acid on the erythrocyte surface were inhibitory for the erythrocyte aggregation.8. Effect of immunoglobulin preparations and plasma expanders: (1) In immunoglobulin preparations, the composition of enzymatic degradation products, the different interaction of erythrocytes with degradation products among ABO-blood grups and the contamination of agglutinins should be taken into consideration. (2) Glucose added in plasma expanders inhibits the erythrocyte aggregation. Less