The erythrocyte adhesiveness/aggregation test to reveal real-time information of rheological relevance in patients with familial and primary hypercholesterolemia before and following plasma exchange

Comparison of the simple red blood cell adhesiveness/aggregation test with the laser-assisted optical rotational cell analyzer: Red blood cell aggregation in patients with coronary artery disease and a healthy control group

BACKGROUND

Red blood cell (RBC) aggregation influences blood flow properties, impacts blood microcirculation and consequently oxygen delivery. Different methods are established to determine RBC aggregation: under static conditions (i.e. the RBC adhesiveness/aggregation test (EAAT)) or under shear conditions (i.e. the laser-assisted optical rotational cell analyzer (LORCA)).

OBJECTIVE

Comparison of these two different methods in detecting the RBC aggregation of patients with coronary artery disease (CAD) and of healthy controls.

METHODS

RBC aggregation was quantified in peripheral venous blood of patients with CAD and healthy controls using EAAT and LORCA.

RESULTS

Both methods detected an increased RBC aggregation in patients with CAD compared to the healthy control group: the ratio of clot-free area to whole area (rCFA) detected with EAAT (15.65 vs. 11.30%), and aggregation index (66.33 vs. 53.90%), shear rate of disaggregation (SDA) (105.59 vs. 69.21 s-1), and upstroke/ttop (0.03 vs. 0.02 au/s) detected with LORCA device were increased, aggregation half time (detected with LORCA) was decreased (2.11 vs. 3.60 s). rCFA (EAAT) correlated with SDA (LORCA).

CONCLUSIONS

Both methods determine an increased RBC aggregation in patients with CAD. However, only one measurement parameter of the LORCA seems to reflect the same RBC aggregation properties as the EAAT.

Plasma dependent reduction in red blood cell aggregation after dextran sulfate low-density lipoprotein apheresis--implications for rheological studies

Red blood cell (RBC) aggregation is increased in familial hypercholesterolemia, and is reduced significantly after low density lipoprotein (LDL) apheresis. The purpose of the present study was to clarify whether this reduction depends on changes in plasma composition, RBC membrane properties, or both. RBC aggregation was determined in a computerized cell flow-properties analyzer, before and after LDL apheresis. We compared RBC aggregation in autologous plasma with aggregation in a plasma-free standard solution (0.5% of dextran 500 kDa) to define the separate contributions of plasma and cellular properties to the observed RBC aggregation. RBC aggregation in autologous plasma was reduced by 35.5% after LDL apheresis (P=0.01) but was not significantly affected when measured in dextran 500. This suggests that LDL apheresis attenuated RBC aggregation by altering plasma composition rather than RBC membrane properties. These results are relevant to the understanding of hemorheological changes which follow therapeutic apheresis in hypercholesterolemic patients.

Inflammation-sensitive proteins and erythrocyte aggregation in atherothrombosis

OBJECTIVE

To find the relative contribution of various inflammation-sensitive proteins including fibrinogen, immunoglobulins (IgG, IgM and IgA), ceruloplasmin and high sensitivity C-reactive protein (hs-CRP) to the induction and/or maintenance of enhanced erythrocyte adhesiveness/aggregation in the peripheral blood of individuals with atherothrombotic risk factors.

METHODS

The degree of erythrocyte adhesiveness/aggregation was determined by a simple slide test and image analysis. In addition, we measured various inflammation-sensitive protein levels including fibrinogen, ceruloplasmin, immunoglobulins and hs-CRP in a group of 234 individuals with atherothrombotic risk factors and healthy ones. Pearson partial correlations and multiple linear regression analysis were performed.

RESULTS

Fibrinogen was found to be the major protein contributing to the enhanced erythrocyte adhesiveness/aggregation, explaining 30% of the model. Fibrinogen and IgG together explained 32.4% of the model. Other inflammation-sensitive proteins did not reach statistical significance and were excluded from the model.

CONCLUSIONS

Among inflammation-sensitive proteins measured in our cohort, fibrinogen is the dominant contributor to erythrocyte adhesiveness/aggregation in the peripheral blood of individuals with atherothrombotic risk factors and healthy ones. These findings may pave the way for the development of therapeutic strategies directed at the attenuation of erythrocyte aggregability in individuals with atherothrombosis.

Automatic 3-dimensional visualization of peripheral blood slides: a new approach for the detection of infection/inflammation at the point of care

CONTEXT

The identification and quantitation of the intensity of the acute-phase response at the point of care might be of clinical relevance.

OBJECTIVE

To report the possibility of automatic screening of unstained peripheral blood slides by using a 3-dimensional image analysis system.

DESIGN

Peripheral venous blood was obtained from children with acute inflammation/infection and examined by an automatic 3-dimensional image analyzer to detect the number of white blood cells as well as to reveal the degree of erythrocyte aggregation, a marker of the humoral phase response.

RESULTS

We included 66 children with acute bacterial infections and 59 with nonbacterial inflammation/infection; mean ages of the 2 groups were 4.3 +/- 3.9 years and 4.2 +/- 3.7 years, respectively (P = .91). The percentages of correct classifications based on discriminant analysis in predicting between bacterial and nonbacterial inflammation/infection were 61.3% by using the white blood cell count, 64.5% by using the percentage of granulocytes, 61.6% by using the degree of erythrocyte aggregation, and 59.2% by using the number of leukocytes counted on the unstained slides. The results of the receiver-operated characteristic curve analysis yielded an area under the curve of 0.714 (P < .001) for the number of granulocytes, 0.699 (P < .001) for the white blood cell count, 0.685 (P < .001) for the number of leukocytes on the slides, and 0.685 (P = .001) for the degree of erythrocyte aggregation. The correlation between the number of leukocytes by the electronic cell analyzer and the number of cells counted on the slides was highly significant (r = 0.85, P < .001).

CONCLUSIONS

It is feasible to use an automatic 3-dimensional image analyzer to reveal the different intensities of the acute-phase response between a group of children with an acute bacterial infection and another with nonbacterial inflammation/infection. These findings might be relevant for potential application at the point of care.

Association of components of the metabolic syndrome with the appearance of aggregated red blood cells in the peripheral blood. An unfavorable hemorheological finding

BACKGROUND

Components of the metabolic syndrome are associated with low-grade inflammation. This can be accompanied by the synthesis of sticky proteins and erythrocyte aggregation.

METHODS

The degree of erythrocyte aggregation was evaluated by a simple slide test and image analysis along with other markers of the acute-phase response, including the white blood cell count (WBCC), erythrocyte sedimentation rate (ESR), fibrinogen and high sensitivity C-reactive protein (hs-CRP) concentrations. Patients were categorized in four groups according to the absence or presence of 1, 2 and 3 or more components of the metabolic syndrome.

RESULTS

We examined a total of 1447 individuals (576 women and 871 men) who gave their informed consent for participation. A significant cardiovascular risk factors, age and hemoglobin adjusted correlation was noted between the degree of erythrocyte aggregation and the number of components of the metabolic syndrome (r = 0.17, p < 0.0005). This correlation was better than that observed for clottable fibrinogen (r = 0.13 p < 0.0005), for ESR (r = 0.11 p < 0.0005) or WBCC (r = 0.13 p < 0.0005). A somewhat better correlation was noted for hs-CRP (r = 0.26 p < 0.0005).

CONCLUSIONS

The multiplicity of components of the metabolic syndrome is associated with enhanced erythrocyte aggregation, probably related to the presence of multiple adhesive macromolecules in the peripheral blood. The enhanced aggregation might contribute to capillary slow flow, tissue deoxygenation as well as vasomotor tone changes in the presence of multiple components of this syndrome.

Erythrocyte adhesiveness/aggregation: a novel biomarker for the detection of low-grade internal inflammation in individuals with atherothrombotic risk factors and proven vascular disease

BACKGROUND

We have introduced a concept of using the erythrocyte as a sensor for the detection of enhanced inflammation-sensitive protein concentrations. We presently evaluated the capability of this new biomarker to detect the presence of inflammation in individuals with a history of a vascular disease as opposed to individuals with atherothrombotic risk factors but no clinically evident vascular disease.

METHODS

The degree of erythrocyte adhesiveness/aggregation was determined in the peripheral venous blood by using a simple blood test. Blood was drawn into a syringe containing sodium citrate and trickled onto a slide at an angle of 30 degrees. The slides were than scanned by a blinded technician by using an image analyzer to determine the area that is covered by the erythrocytes.

RESULTS

One hundred fifty-six subjects (61 women and 95 men) of 2586 (1238 women and 1348 men) met the criteria of a definite vascular disease (history of stroke, myocardial infarction, coronary artery bypass grafting, or peripheral vascular disease). The degree of erythrocyte aggregation was significantly (P = .008) higher in men, but not in women, with vascular disease as opposed to these without a vascular disease. The results of receiver operating characteristic curve analysis confirmed the diagnostic superiority of the erythrocyte aggregation biomarker over other commonly used markers of the acute phase in men. Similar results were obtained by using discriminant analysis. Finally, a significant correlation was found between the degree of erythrocyte aggregation and other markers of the acute phase suggesting its relevance for the detection and quantitation of low-grade inflammation in individuals with atherothrombosis.

CONCLUSION

Erythrocyte adhesiveness/aggregation may be a useful biomarker to detect internal inflammation in individuals with atherothrombosis.

Rheological determinants in patients with Gaucher disease and internal inflammation

The purpose of this study was to determine whether the inflammatory response in patients with Gaucher disease (GD) is accompanied by enhanced adhesiveness/aggregation of both red and white blood cells. Sixty patients with GD and matched controls were included. The degree of erythrocyte and leukocyte adhesiveness/aggregation was determined by using a simple slide test and image analysis. Patients with GD had significantly elevated concentrations of fibrinogen (328 vs. 262 mg/dl, P < 0.0001) and accelerated erythrocyte sedimentation rates (27 vs. 13 mm/H, P < 0.005). This was accompanied by a significantly enhanced degree of erythrocyte (75 vs. 85, P < 0.0001) and leukocyte (3.5 vs. 1.3, P < 0.002) adhesiveness/aggregation. The low-grade, smoldering, and subclinical internal inflammation in individuals with GD is accompanied by an increased degree of erythrocyte and leukocyte adhesiveness/aggregation. These findings might have rheological consequences in terms of microcirculatory slow flow and tissue hypoxemia.

Sex differences in the expression of haemorheological determinants in individuals with atherothrombotic risk factors and in apparently healthy people

BACKGROUND

Increased red cell aggregation can be detrimental, leading to slow capillary blood flow and tissue hypoxaemia. Sex differences in the degree of erythrocyte adhesiveness/aggregation in the peripheral blood have not been clearly shown.

OBJECTIVES

To determine whether there are sex differences in the expression of erythrocyte adhesiveness/aggregation in the peripheral blood in individuals with atherothrombotic risk factors and in apparently healthy people.

METHODS

From a cohort of 965 participants in the Tel Aviv Medical Centre inflammation survey, 192 pairs of different sex were matched for age, body mass index, hip and waist circumferences, cardiovascular risk factors, and the intake of active cardiovascular drugs.

RESULTS

Women had an enhanced degree of red cell aggregation (p < 0.0005) as well as increased concentrations of inflammation sensitive proteins including fibrinogen and C reactive protein. Women had a lower haemoglobin concentration than men, but this did not affect the degree of erythrocyte adhesiveness/aggregation.

CONCLUSIONS

The significant increase in red blood cell adhesiveness/aggregation in the peripheral blood of women with atherothrombosis could be relevant to the more eventful course that some women experience during and following acute ischaemic disease.

Comparative Analysis Between Dextran Sulfate Adsorption and Direct Adsorption of Lipoproteins in their Capability to Reduce Erythrocyte Adhesiveness/Aggregation in the Peripheral Blood

The purpose of this study was to compare the degree of erythrocyte adhesiveness/aggregation (EAA) reduction of two low-density lipoprotein (LDL) apheretic procedures, namely direct adsorption of lipoproteins (DALI) and dextran sulfate adsorption (DSA). A significant (P < 0.001) reduction of EAA was noted in six hypercholesterolemic patients who underwent a total of 40 apheretic sessions and no difference was noted in the degree of EAA reduction by the two techniques. Thus. being a real-time and point-of-care test, the erythrocyte adhesiveness/aggregation test can be applied in relevant situations of acute ischemia, where therapeutic LDL apheresis could improve the hemorheology of individuals with increased concentrations of cholesterol and inflammatory sensitive proteins.

The degree of red blood cell aggregation on peripheral blood glass slides corresponds to inter-erythrocyte cohesive forces in laminar flow

OBJECTIVE

To determine the degree of correlation between red blood cell (RBC) aggregation on peripheral blood glass slides (PBGS) as determined by image analysis and the inter-erythrocytic cohesive forces as determined in a computerized cell flow properties analyzer (CFA).

STUDY DESIGN

RBC aggregation was assessed using both systems simultaneously in healthy volunteers, obese patients and hypercholesterolemic individuals before and following LDL apheresis.

RESULTS

A significant (r = 0.5, p < 0.001) correlation was noted between the flow-dependent average aggregate size (AAS) obtained in the CFA and the degree of RBC aggregation on peripheral blood glass slides. Moreover, the enhanced RBC aggregation on the slides was positively associated with the appearance of larger aggregates in the CFA (r = 0.5, p < 0.001) and inversely with the formation of smaller aggregates (r = -0.27, p < 0.04). A similar reduction in RBC aggregation following LDL apheresis was noted in both systems.

CONCLUSIONS

The phenomenon of RBC aggregation on peripheral blood glass slides is governed by significant inter-erythrocytic cohesive forces and is not a result of a mere coincidental superimposition of cells. The slide test offers a rapid and simple method of evaluating rheologically significant RBC aggregation, and may allow stratification of patients at risk for atherothrombosis.

Significant dominance of fibrinogen over immunoglobulins, C-reactive protein, cholesterol and triglycerides in maintaining increased red blood cell adhesiveness/aggregation in the peripheral venous blood: a model in hypercholesterolaemic patients

BACKGROUND

It is not clear what is the relative importance of fibrinogen, immunoglobulins, highly sensitive C-reactive protein (hs-CRP), cholesterol and triglyceride concentrations on the appearance of aggregated red blood cells in the peripheral blood.

DESIGN

Six hypercholesterolaemic patients undergoing regular LDL apheresis that were examined repeatedly before and following the procedure.

RESULTS

We determined the degree of erythrocyte adhesiveness/aggregation in relation to the concentration of the above-mentioned macromolecules in 80 samples. In a linear logistic regression the respective R2 values for fibrinogen, total cholesterol, triglycerides, hs-CRP, IgG, IgM and IgA were 0.45 (P<0.0001), 0.2 (P<0.0001), 0.02 (P=0.02), 0.001 (P=NS) and 0.002 (P=NS), respectively. We further analyzed the potential of ApoA, ApoB and Lpa to participate in red cell adhesiveness/aggregation and found them to be not significant.

CONCLUSIONS

In a milieu of adhesive macromolecules, lipids and inflammation-sensitive proteins including fibrinogen, total cholesterol, triglycerides, hs-CRP and immunoglobins G, M and A, fibrinogen has a dominant role in maintaining the red blood cell adhesiveness/aggregation in the peripheral venous blood. These findings are relevant for the research directed at finding new apheretic modalities to reduce the degree of red blood cell adhesiveness/aggregation in the peripheral blood.

The appearance of aggregated erythrocytes in the peripheral blood of individuals with insulin resistance

BACKGROUND

Insulin resistance is associated with low-grade inflammatory response. The probability that the acute-phase response is associated with enhanced erythrocyte adhesiveness/aggregation was not explored.

METHODS

The degree of erythrocyte adhesiveness/aggregation was evaluated by using a simple slide test. The insulin resistance was evaluated by insulin and glucose concentrations after a night of fasting. The inflammatory response was evaluated by variables of acute-phase response.

RESULTS

A significant correlation (r = -0.2, p = 0.02) was noted between insulin resistance expressed as the HOMA index and the degree of erythrocyte adhesiveness/aggregation. This was probably due to the concomitant acute-phase response and the presence of increased amounts of inflammation-sensitive proteins that were found to correlate significantly with the degree of erythrocyte adhesiveness/aggregation. In the multiple linear regression analysis, erythrocyte sedimentation rate and fibrinogen concentration but not HOMA index were found to correlate significantly (p < 0.0001 and p = 0.0007 respectively) with the degree of red blood cell adhesiveness/aggregation.

CONCLUSIONS

Insulin resistance is associated with an enhanced degree of erythrocyte adhesiveness/aggregation and this is related to the presence of enhanced inflammation-sensitive plasma proteins that are part of the acute-phase response. These findings might have hemorheological consequences and might contribute to the pathophysiology of the insulin-resistance syndrome.

Inflammation at a glance: erythrocyte adhesiveness/aggregation test to reveal the presence of inflammation in people with atherothrombosis

The erythrocyte adhesiveness/aggregation test is a new biomarker to detect low-grade inflammation in patients with atherothrombosis. In a group of 30 individuals with an acute ischemic event, the variability of EAAT during a follow-up period was similar to those obtained for other commonly used markers of the acute phase response, suggesting the potential clinical use of this novel marker.

The erythrocyte adhesiveness/aggregation test for the detection of an acute phase response and for the assessment of its intensity

We have developed a simple slide test and image analysis to reveal the state of erythrocyte adhesiveness/aggregation in the peripheral blood of patients with various degrees of the humoral acute phase response. The significant correlation between the results of the erythrocyte adhesiveness/aggregation test (EAAT), the erythrocyte sedimentation rate and fibrinogen concentration support the notion that it is possible to use the EAAT as a marker for the intensity of the acute phase response. Within a group of 860 individuals, we were able to differentiate effectively between groups of patients with a different intensity of humoral acute phase response. The present study confirms previous observations that support the applicability of the EAAT to routine clinical practice.