Modification of red blood cells for laboratory quality control use

COVID-19 Antibody Detection and Assay Performance Using Red Cell Agglutination

Red cells can be labeled with peptides from the SARS-CoV-2 spike protein (C-19 kodecytes) and used as reagent cells for serologic screening of SARS-CoV-2 antibodies. We evaluated 140 convalescent COVID-19 donors and 275 healthy controls using C19-kodecytes. The analytical performance of the C19-kodecyte assay was compared with a virus neutralizing assay and two commercial chemiluminescent antibody tests (Total assay and IgG assay, Ortho). The C19-kodecyte assay detected SARS-CoV-2 antibodies with a sensitivity of 92.8% and specificity of 96.3%, well within the minimum performance range required by FDA for EUA authorization of serologic tests. The Cohen's kappa coefficient was 0.90 indicating an almost perfect agreement with the Total assay. The Spearman's correlation coefficient was 0.20 with the neutralizing assay (0.49 with IgG, and 0.41 with Total assays). The limited correlation in assay reaction strengths suggested that the assays may be influenced by different antibody specificities. The C19-kodecyte assay is easily scalable and may vastly improve test capacity in any blood typing laboratory using its routine column agglutination platforms. IMPORTANCE We recently developed a red cell based assay to detect SARS-CoV-2 antibodies in human plasma. In the current study, we show the hands-on application of this assay in a group of COVID-19 convalescent plasma donors and healthy individuals. We compared our assay against three published assays, including two that are widely used for patient care in the United States. Our assay compared well with all three assays. Our easily scalable assay can be used for population-wide screening of SARS-CoV-2 antibody status. It can be readily established in any hospital blood bank worldwide using its routine equipment.

Evaluation of kodecytes using function-spacer-lipid constructs as a survey material for external proficiency testing for ABO subgrouping

BACKGROUND

It is not easy to find natural red blood cells (RBCs) with weak A (A_w ) or weak B phenotype (B_w ) for use as quality controls in ABO subgroup testing (subgrouping). The aim of this study was to prepare RBC kodecytes with synthetic blood group A and/or B function-spacer-lipid (FSL) constructs and to evaluate the possibility of using such kodecytes as a survey material for an external proficiency test (PT) to improve the quality of subgroup analysis.

METHODS

Three types of survey samples, including O phenotype RBCs and A kodecytes with A_w (0.02 mg/mL FSL-A solution) and B kodecytes with B_w (0.15 mg/mL FSL-B solution) were sent to 53 laboratories for an educational trial of PT for subgrouping. Cell typing was done using the manual tube technique.

RESULTS

Forty-three laboratories responded, and the re-activities of the survey samples varied from 0 to 4+ against anti-A and anti-B monoclonal reagents(MoAbs). Twenty-nine laboratories (67%) correctly grouped the B_w kodecytes as B_w . Fifteen (35%), 21 (48%), and 6 (13%) laboratories grouped the A_w kodecytes as A_w , A₂ , and O phenotypes, respectively. The anti-A MoAb clone affects the results of cell typing for A_w kodecytes. The stability of kodecytes was similar to that of natural O RBCs during storage.

CONCLUSION

Our kodecytes were useful as a survey material, and the survey results showed the necessity of materials for PT for subgrouping to improve the quality of laboratory analysis regardless of the different reactions according to the MoAb.

Structural diversity and biological importance of ABO, H, Lewis and secretor histo-blood group carbohydrates

ABO, H, secretor and Lewis histo-blood system genes control the expression of part of the carbohydrate repertoire present in areas of the body occupied by microorganisms. These carbohydrates, besides having great structural diversity, act as potential receptors for pathogenic and non-pathogenic microorganisms influencing susceptibility and resistance to infection and illness. Despite the knowledge of some structural variability of these carbohydrate antigens and their polymorphic levels of expression in tissue and exocrine secretions, little is known about their biological importance and potential applications in medicine. This review highlights the structural diversity, the biological importance and potential applications of ABO, H, Lewis and secretor histo-blood carbohydrates.

Training students in serologic reaction grading increased perceptions of self-efficacy and ability to recognize serologic reactions but decreased grading accuracy

BACKGROUND

The ability to recognize and grade serologic reactions in manual techniques remains an important skill both for reference laboratories and in disaster-relocated laboratory services. Developing skills in recognizing and grading serologic reactions is limited to some extent by the range of samples available.

STUDY DESIGN AND METHODS

Twenty-six students studying transfusion science were presented with blinded grading panels consisting of mixes of natural cells and kodecytes (natural cells modified with synthetic blood group antigens) representing a range of serologic grades. Results from 15-minute exercises over 17 contact weeks were assessed to determine if training with grading panels would have an impact on the ability of students to recognize and correctly grade serologic reactions. Twenty-one clinically active practitioners also took part in a single analysis.

RESULTS

Grading exercises found that the use of kodecytes and natural negative cells were able to identify deficiencies in both students' and practitioners' ability to recognize negative and grade serologic reactions. The seventeen 15-minute exercises undertaken with students revealed that although there was some improvement in performance in recognizing positive and negative serologic reactions there was also a degradation in ability to accurately grade. Self-assessment showed a major improvement in students' self-efficacy.

CONCLUSIONS

The use of serologic grading panels created with kodecytes was suitable as a tool to recognize and monitor serologic grading abilities. Evidence suggests that for both students and practitioners to gain and sustain competency in serologic reaction recognition and grading, they will require ongoing training and monitoring of competence.

Labeling of influenza viruses with synthetic fluorescent and biotin-labeled lipids

Direct labeling of virus particles is a powerful tool for the visualization of virus-cell interaction events. However, this technique involves the chemical modification of viral proteins that affects viral biological properties. Here we describe an alternative approach of influenza virus labeling that utilizes Function-Spacer-Lipid (FSL) constructs that can be gently inserted into the virus membrane. We assessed whether labeling with fluorescent (fluo-Ad-DOPE) or biotin-labeled (biot-CMG2-DOPE) probes has any deleterious effect on influenza virus hemagglutinin (HA) receptor specificity, neuraminidase (NA) activity, or replicative ability in vitro. Our data clearly show that neither construct significantly affected influenza virus infectivity or viral affinity to sialyl receptors. Neither construct influenced the NA activities of the influenza viruses tested, except the A/Puerto Rico/8/34 (H1N1) strain. Our data indicate that lipid labeling provides a powerful tool to analyze influenza virus infection in vitro.

FSL constructs: a simple method for modifying cell/virion surfaces with a range of biological markers without affecting their viability

The ability to modify/visualize biological surfaces, and then study the modified cell/virion in a range of in vitro and in vivo environments is essential to gaining further insight into the function of specific molecules or the entire entity. Studies of biological surface modification are generally limited to genetic engineering of the organism or the covalent attachment of chemical moieties to the cell surface(1,2). However these traditional techniques expose the cell to chemical reactants, or they require significant manipulation to achieve the desired outcome, making them cumbersome, and they may also inadvertently affect the viability/functionality of the modified cell. A simple method to harmlessly modify the surface of cells is required. Recently a new technology, KODE Technology has introduced a range of novel constructs consisting of three components: a functional head group (F), a spacer (S) and a lipid tail (L) and are known as Function-Spacer-Lipid or FSL constructs3. The spacer (S) is selected to provide a construct that is dispersible in water, yet will spontaneously and stably incorporate into a membrane. FSL construct functional moieties (F) so far include a range of saccharides including blood group-related determinants, sialic acids, hyaluronan polysaccharides, fluorophores, biotin, radiolabels, and a range of peptides(3-12). FSL constructs have been used in modifying embryos, spermatozoa, zebrafish, epithelial/endometrial cells, red blood cells, and virions to create quality controls systems and diagnostic panels, to modify cell adhesion/ interaction/ separation/ immobilization, and for in vitro and in vivo imaging of cells/virions(3-12). The process of modifying cells/virions is generic and extremely simple. The most common procedure is incubation of cells (in lipid free media) with a solution for FSL constructs for 1-2 hours at 37°C(4-10). During the incubation the FSL constructs spontaneously incorporate into the membrane, and the process is complete. Washing is optional. Cells modified by FSL constructs are known as kodecytes(6-9), while virions are kodevirions(10). FSL constructs as direct infusions and kodecytes/kodevirions have been used in experimental animal models(7,8,10). All kodecytes/kodevirions appear to retain their normal vitality and functionality while gaining the new function of the F moiety(7,8,10,11). The combination of dispersibility in biocompatible media, spontaneous incorporation into cell membranes, and apparent low toxicity, makes FSL constructs valuable research tools for the study of cells and virions.