PubMed · 7249566
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R D Hutton. 1981. Polycythaemic discrepancy.. https://pubmed.ncbi.nlm.nih.gov/7249566/
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Various techniques have been used to assess the flow properties of blood and blood cells in a range of clinical situations. Filtration through microfilters offers a single technique for measuring the flow properties of all cellular components of blood in one experiment but depends on an assumed ability to recognize cells that make up <10% of leucocytes. The remaining leucocytes, labelled fast leucocytes, were previously presumed to be lymphocytes and granulocytes. This study confirmed the identities of these fast leucocytes as those of lymphocytes and granulocytes in undiluted blood. The transit time for lymphocytes (1.2 s) and granulocytes (1.6 s) is close to that recorded for fast leucocytes (1.7 s). The resistance of each type of blood cell to flow through 5 microm filters was defined in this study as the product of the concentration of that cell in blood and its transit time through a pore in the filter. The total resistance to flow of healthy blood through the filter is 4.46 x 10(7) s/ml and is attributed to plasma (2.7%), red cells (25.9%), fast leucocytes (25.3%) and slow leucocytes (46.1%). In a cohort of 21 men with peripheral arterial disease the total resistance was increased to 7.82 x 10(7) s/ml and attributed to plasma (1.5%), red cells (14.5%), fast leucocytes (21.0%) and slow leucocytes (63.00%). This analysis therefore provides a single test for assessing the flow properties of all the cellular components of blood and plasma.
Impaired blood flow due to abnormal rheologic characteristics results in a multiplicity of clinical manifestations, collectively termed the hyperviscosity syndrome. A basic knowledge of the principles of rheology is important in the understanding of its pathophysiology, especially the relationship between viscosity and flow conditions. The flow characteristics in different types of blood vessels are also determinants in the location of the clinical manifestation. The syndrome can occur in a wide variety of diseases and is best grouped according to the causative element or elements in blood. Abnormalities in the cellular components of blood can occur in the quantity and the quality of erythrocytes, leukocytes, and platelets. Abnormal plasma components can also be in both the quantity and quality of the plasma proteins. Clinical manifestations are the result of vascular occlusion, especially in the microcirculation. The altered rheologic characteristics of either the cellular or the protein component may be temperature dependent, being abnormal only at temperatures below 37 degrees C, so that only the cooler parts of the body are affected. The management of these conditions should be primarily directed at the removal of the abnormal component. At the same time, it should be accompanied by measures that can control the production of the causative element.
Most biomedical textbooks teach that coagulation and thrombosis are primarily a function of endothelial cells, platelets, and soluble coagulation factors. Red blood cells, in contrast, are generally regarded as innocent bystanders, passively entrapped in a developing thrombus as they flow through the vasculature. This review summarizes evidence that demonstrates an active role for red cells in normal and pathologic hemostasis. We then evaluate the possible molecular mechanisms whereby a usually inert erythrocyte can actively contribute to the processes of clot formation.