Erythrocyte Aggregation: Function, Role & Diseases

During erythrocyte aggregation, red blood cells cluster together and clump together. The phenomenon is physiologic to some degree, especially in the smaller capillaries. In immune complex diseases, for example, this physiologic degree is exceeded.

What is erythrocyte aggregation?

In erythrocyte aggregation, red blood cells cluster together and clump together. Red blood cells are also called erythrocytes. Erythrocytes are organelle-less cells that are unable to divide. The cells have a biconcave flattened shape whose main component is red hemoglobin. The shape of the cells increases their surface area, creating better conditions for gas exchange. Erythrocytes are highly flexible and occur in several dozen different shape variants, such as anulocyte or macrocyte. They can adapt their shape and in this way migrate through capillaries with a smaller diameter than they themselves possess. Under the cell membrane of the cells lies a filament network that radiates into the membrane. The network of filaments gives red blood cells their dense structure and creates what is known as an erythrocytic cytoskeleton. Proteins such as spectrin and ankyrin are essential for their structural shape. There is an attractive force between red blood cells. This force becomes effective at low blood flow rates. In the course of so-called pseudoagglutination, erythrocytes assemble into rouleaux in order to be able to pass vessels more easily. The rouleaux thus corresponds to a money roll-like agglutination of red blood cells, which is made possible by plasma proteins. The dissolution of a rouleaux is already possible by means of slight mechanical forces. Red cell pseudoagglutination is a form of red cell aggregation or red cell agglomeration. Each type of aggregation corresponds to an agglomeration of biologically physiological elements.

Function and task

Erythrocyte aggregation occurs on the basis of attractive forces as they exist between individual erythrocytes. Because these attractive forces are relatively small, aggregation does not occur at regular flow rates. Pseudoaggregation, or money roll formation, occurs predominantly when the blood is flowing slowly or at a standstill. In this situation, the red blood cells clump together to form a rouleaux. This pseudoagglutination is reversible. Weak forces are enough to dissolve the “money roll” of red blood cells again. The aggregation of the erythrocytes is due to different influencing factors in addition to the attractive forces between the blood cells. For example, the degree of aggregation is influenced by factors such as membrane deformability and sialylation. The plasmaproteinergic masking of negative charges also plays a role in the degree of agglutination. Money roll formation is particularly important in the context of blood viscosity. Thus, aggregation, among other factors, determines the degree of viscosity. Human blood does not behave like a Newtonian fluid, but combines the properties of a liquid medium with material properties. Thus, blood shows non-proportional and rather erratic flow behavior. In this context, the so-called Fåhraeus-Lindqvist effect, which is based on the deformability of the red blood cells, is of decisive importance. In the smaller capillaries, the red blood cells deform into stomatocytes. They are displaced into the axial flow by shear forces close to the wall. This phenomenon corresponds to the so-called axial migration of erythrocytes and gives rise to a cell-poor marginal flow. The Fåhraeus-Lindqvist effect lowers the effective blood viscosity in vessels with narrow lumens, thus preventing the formation of stenosis that could occur due to the attractive forces between erythrocytes. Aggregation of erythrocytes into the long, roll-like, and sometimes branched structures of the rouleaux occurs primarily in the region of the smaller capillaries and appears to be mediated by plasma proteins such as fibrinogen. Different influencing factors promote aggregation. In addition to high concentrations of immunoglobulins, platelets, alpha2-globulins, dextrans, albumin, and polylysine are considered to promote aggregation. In addition, physical influences such as heat and dryness contribute to pseudoaggregation.

Diseases and ailments

General medicine assesses erythrocyte aggregation in terms of pseudoaggregation as a physiological process. This view is contradicted by alternative medicine. Money roll formation is considered by many alternative physicians to be a pathologic event. In alternative medicine, therefore, the phenomenon is used to diagnose various diseases. In this context, alternative physicians resort to dark field vital blood diagnostics. In the corresponding tests, alleged blood damage caused by electromagnetic fields can also be detected. Meanwhile, scientific studies do not allow general medicine to identify any connection between the money roll formation of red blood cells and damage to the blood. Orthodox physicians also consider damage to the blood by electromagnetic fields to be inaccurate. In the blood smear, demonstrably healthy people show an erythrocyte aggregation in the sense of a pseudoaggregation or money roll formation. In orthodox medicine, erythrocyte aggregation is considered physiological up to a certain degree. However, if this degree is exceeded, even orthodox physicians speak of a pathological phenomenon. A particularly high degree of erythrocyte and platelet aggregation is seen, for example, in the context of so-called immune complex diseases. These diseases are caused by deposits of immune complexes within the tissues. The individual antibodies can be directed against foreign antigens or against autoantigens. The latter is the case, for example, in systemic lupus erythematosus or rheumatoid arthritis. As a rule, these are IgG isotype antibodies that activate the complement system and thus cause inflammation. Blood clotting is affected by the inflammation. Increased aggregation of red blood cells occurs in this setting because fibrinogen, for example, shows a beneficial effect on red blood cell aggregation.