Survival Time of Cross-Match Incompatible Red Blood Cells in Adult Horses

Major crossmatch compatibility of rabbit blood with rabbit, canine, and feline blood

OBJECTIVE

To evaluate the major crossmatch compatibility between rabbit recipients, rabbit donors, and the major canine and feline blood types.

DESIGN

Prospective in vitro study in December 2021.

SETTING

Academic veterinary teaching hospital.

ANIMALS

Whole blood samples were collected from 11 healthy New Zealand White rabbits (Oryctolagus cuniculus) with no previous transfusion history. Three pigtail segments were acquired from dog erythrocyte antigen (DEA)-1-positive, DEA-1-negative, and feline type A blood units. Whole blood was collected from a healthy type B blood donor cat.

INTERVENTIONS

Blood from each rabbit recipient underwent a major crossmatch using standard tube crossmatch methodology with itself and the following donor blood types: rabbit, DEA-1-positive, DEA-1-negative, feline type A, and feline type B.

MEASUREMENTS AND MAIN RESULTS

Self-crossmatches and crossmatches between rabbit recipients and conspecific donors were negative for hemolysis and agglutination. Crossmatches between rabbit recipients and canine and feline donors yielded no hemolysis but produced varying degrees of macroscopic and microscopic agglutination. Rabbit recipients had 1.4 (95% confidence interval: 1.1-1.8) times the risk of macroscopic agglutination when major crossmatched with canine blood compared to feline blood. No significant difference in agglutination was found between DEA-1-positive and DEA-1-negative or feline type A and type B donors.

CONCLUSIONS

These findings support allogeneic blood transfusions between rabbits being highly compatible and suggest rabbits have naturally occurring alloantibodies against both canine and feline red blood cells. However, feline red blood cells had a lower rate of in vitro incompatibility on major crossmatch, suggesting potentially higher in vivo compatibility if an emergency xenotransfusion is needed. Further prospective research is needed to determine if xenotransfusion is associated with a higher incidence of acute and delayed transfusion reactions in rabbits than allogeneic transfusions.

Effect of leukoreduction on the metabolism of equine packed red blood cells during refrigerated storage

BACKGROUND

Understanding of the biochemical and morphological lesions associated with storage of equine blood is limited.

OBJECTIVE

To demonstrate the temporal sequences of lipid and metabolic profiles of equine fresh and stored (up to 42 days) and leukoreduced packed red blood cells (LR-pRBC) and non-leukoreduced packed RBC (nLR-pRBC).

ANIMALS

Packed RBC units were obtained from 6 healthy blood donor horses enrolled in 2 blood banks.

METHODS

Observational study. Whole blood was collected from each donor using transfusion bags with a LR filter. Leukoreduction pRBC and nLR-pRBC units were obtained and stored at 4°C for up 42 days. Sterile weekly sampling was performed from each unit for analyses.

RESULTS

Red blood cells and supernatants progressively accumulated lactate products while high-energy phosphate compounds (adenosine triphosphate and 2,3-Diphosphoglycerate) declined. Hypoxanthine, xanthine, and free fatty acids accumulated in stored RBC and supernatants. These lesions were exacerbated in non-LR-pRBC.

CONCLUSION AND CLINICAL IMPORTANCE

Leukoreduction has a beneficial effect on RBC energy and redox metabolism of equine pRBC and the onset and severity of the metabolic storage lesions RBC.

Validation of a human paper-based blood typing method for use in pet pigs

BACKGROUND

Evidence-based medical practices for pet pigs are needed. EldonCard is a human blood-typing card shown to be rapid and reliable in identifying blood phenotypes of pet pigs. The objective of this study was to validate EldonCard by determining its reliability, reproducibility, and robustness for its routine use in the clinical setting.

KEY FINDINGS

Twenty-four venous blood samples from pet pigs were collected for a prospective in vitro study. Blood genotypes ("EAAA0 " and "EAA00 ") were identified in 15 samples via polymerase chain reaction (PCR). All samples were phenotyped ("A," "Aweak ," and "0" or "-") via EldonCard. Kappa (κ) statistics measured the level of agreement between 2 raters, and between EldonCard and PCR. McNemar's test determined if an association between the blood types and EldonCard or PCR exists, with significance at P < 0.05. Agreement between raters and methods was perfect (60/60 [100%], κ:1, P < 0.001; 15/15 [100%], κ:1, P < 0.001). There was no difference in the proportions of blood groups based on method.

SIGNIFICANCE

In conjunction with previous data, EldonCard is a rapid, accurate, reliable, precise, and robust in-clinic blood-typing method for the A0 system of pet pigs. EldonCard is now a validated blood-typing tool for the A0 system of pet pigs and maybe used for pretransfusion screenings and identification of donors and recipients.

Prevalence of AO blood group and level of agreement for AO blood-typing methods in pet pigs from Louisiana

OBJECTIVES

Pet pigs are a species of growing medical interest, and evidence-based practices for blood transfusions are needed. The objectives of this study were to quantify the prevalence of 3 blood group (Bg) phenotypes ("A" and "Aweak " resulting from EAAAA and EAAAO , "0" from EAA00 , or "-" from EAA00 or SSS alleles) in pet pigs and compare results using a human blood-typing card (EldonCard), standard saline agglutination (SSA), and polymerase chain reaction (PCR) sequencing.

DESIGN

Cross-sectional study.

SETTING

University veterinary teaching hospital.

ANIMALS

Ninety-seven pet pigs from Louisiana.

INTERVENTIONS

Blood was sampled from randomly selected pet pigs of various breeds, anticoagulated with EDTA, and typed using each investigated test according to the manufacturers' directions or standard laboratory technique. Samples for PCR analysis were stored at -80°C until analysis. Phenotypes were screened via EldonCard. Association between Bg and sex was investigated using chi-square test, with significance at P < 0.05. Kappa (κ) statistic was used to measure the level of agreement between the 3 tests.

MEASUREMENTS AND MAIN RESULTS

Pot-bellied pigs represented the majority (84.5%) of this population, with 52 (53.6%) males and 45 (46.4%) females. Genotypic frequencies were 30%, 30%, and 40% for "EAAAA ," "EAAAO ," and "EAA00 ," respectively. Based on EldonCard, 38 phenotypes were classified as "A," 5 as "Aweak ," and 54 as "0" or "-." Results were identical for Bg, with the 3 tested techniques in 90% (45/50) of samples. Agreement between EldonCard and PCR was almost perfect (49/50 [98%], κ = 0.959; P < 0.001). Agreement between SSA and PCR, and EldonCard and SSA was substantial (46/50 [92%], κ = 0.803, P < 0.001 and 93/97 [95.9%], κ = 0.764, P < 0.001, respectively).

CONCLUSIONS

The most common blood type was "0" or "-" (55.7%), followed by "A" (39.2%) and "Aweak " (5.1%). There was strong agreement between EldonCard and PCR testing. EldonCard allowed for rapid and reliable phenotype identification ("A," "Aweak ," and "0" or "-") and represents a clinically applicable laboratory method for blood typing in pet pigs.

Agglutination and hemolytic crossmatching to determine transfusion reaction differences between large and small breed goats

BACKGROUND

Blood transfusions are performed frequently in goats, but crossmatches are rarely performed.

HYPOTHESIS/OBJECTIVES

Determine differences in the frequency of agglutination and hemolytic crossmatch reactions between large and small breed goats.

ANIMALS

Healthy adult goats, 10 large and 10 small breed.

METHODS

Two hundred eighty major and minor agglutination and hemolytic crossmatches: 90 large breed donor to large breed recipient (L-L), 90 small breed donor to small breed recipient (S-S), 100 large breed donor to small breed recipient (L-S). A linear mixed model with treatment group (L-L, S-S, L-S) as a fixed effect and individual crossmatch as a random effect was used to identify variations in reaction frequency among groups and individuals.

RESULTS

Frequency of major agglutination reactions for L-L, S-S, and L-S were 3/90 (3.3%), 7/90 (7.8%), and 10/100 (10.0%), respectively. Frequency of major hemolytic reactions for L-L, S-S, and L-S were 27/84 (32.1%), 7/72 (9.7%), and 31/71 (43.7%). Individual pairings and groupings had no effect on agglutination reactions. Individual pairings had no effect on the frequency of hemolytic reactions. For major hemolytic crossmatches, pairwise comparisons identified higher frequencies of reactions when comparing L-L to S-S (P = .007) and L-S to S-S (P < .001).

CONCLUSION AND CLINICAL IMPORTANCE

Goats experience increased frequencies of hemolytic reactions compared to agglutination. Significant increases in hemolysis were seen between large breed donors and small breed recipients, compared to small breed pairings. Additional studies are required to determine correlations between crossmatches and transfusion reactions.

Monitoring the positive conversion of anti-erythrocyte antibodies in blood transfusion donor horses

To confirm the positive conversion of antibodies against erythrocyte antigens in horses, possible blood transfusion donor horses selected from draft horse populations were periodically monitored with an indirect antiglobulin (Coombs) test for approximately 3 years. In this study, 19 horses (16 females and 3 males) were investigated, and five mares showed alloantibodies during the monitoring period. Four mares were typically pregnant when positive conversion was detected, whereas no particular cause of conversion could be observed for one mare based on its clinical records. In the analyzed horses, most positive conversions were possibly due to pregnancy, as conversion occurred more often during this period than after parturition. Pregnancy is considered a key event for positive conversion. Additionally, in cases in which unknown causative sensitization is confirmed, continuous monitoring with a test to detect antibodies should be performed, even if the possible donor is selected and maintained.

Blood types and antibody profiles of Straight Egyptian Arabian horses in Qatar: Preliminary results

The characterization of the blood groups, antibody profiles, and its distribution pattern among different horse breeds and geographic locations, can be very useful in life-threatening situations where a blood transfusion is needed, and compatibility tests are not readily available. This study estimated the distribution of blood types and antibody profiles in Straight Egyptian Arabian horses from Qatar. A total of 20 Straight Egyptian Arabian horses, from multiple origins and genetic background were included. Venous blood from each horse was typed and screened for anti-red blood cell (RBC) hemolytic and agglutinating antibodies. Descriptive statistical analysis and Fisher Exact test were applied, considering 95% confidence interval (95% CI). All included horses (100%) had Aa and Ca blood types (95% CI: 83.2%-100.0%). Other blood types found less frequently included Ua (50%), Qc (45%), Pa (40%), Qb (25%) and Qa (5%). Only horses with travel history developed anti-RBC antibodies (6 out of 9), however, no horse carried more than one type of anti-RBC antibodies, supporting the premise that environmental factors may influence the development of alloantibodies. Although pre-transfusion testing regardless the circumstances should be prioritized, even considering a small population of horses, our findings suggest that Straight Egyptian Arabian horses in Qatar could be safely used as blood donors, due to the apparent omnivalence of Aa and Ca blood types and lower incidence of alloantibodies, important in emergency situations where pre-transfusion testing is unavailable.

Blood Transfusion in Equids—A Practical Approach and Review

Simple Summary

Transfusion medicine is an accessible, technically simple, and often lifesaving tool that can be used in both field and hospital settings, in cases of significant bleeding or anemia. A thorough understanding of the indications, methodology and complications of blood transfusion allows the practitioner to identify cases where administration of whole blood is necessary, and how to safely perform the transfusion. This review collects the current literature surrounding blood transfusion into one readily accessible document to allow clinicians a comprehensive understanding of all aspects of equine blood transfusion, while serving as a reference for performing these procedures.

Abstract

Transfusion medicine is a crucial part of equine intensive and critical care. Blood transfusions can save lives in both acute and chronic cases of anemia, hemorrhage, and hemolysis. It is vital to have a comprehensive theoretical and practical understanding of the techniques, implications, risks, and complications. This review covers the physiology and pathophysiology of conditions requiring transfusion, as well as step by step guidance for practitioners of all experience levels. This review is designed to serve as a practical reference for those who are treating horses in either the field or hospital setting. It aims to provide both theoretical background and easy to locate formulae with guidance that is easy to refer to in a critical situation. When risks and benefits are well understood, these techniques can be confidently employed in critical situations to improve outcomes and save lives.

Calculating and selecting fluid therapy and blood product replacements for horses with acute hemorrhage

BACKGROUND

Blood products, crystalloids, and colloid fluids are used in the medical treatment of severe hemorrhage in horses with a goal of providing sufficient blood flow and oxygen delivery to vital organs. The fluid treatments for hemorrhage will vary depending upon severity and duration and whether hemorrhage is controlled or uncontrolled.

DESCRIPTION

With acute and severe controlled hemorrhage, treatment is focused on rapidly increasing perfusion pressure and blood flow to vital organs. This can most easily be accomplished in field cases by the administration of hypertonic saline. If isotonic crystalloids are used for resuscitation, the volume administered should be at least as great as the estimated blood loss. Following crystalloid resuscitation, clinical signs, HCT, and laboratory evidence of tissue hypoxia may help determine the need for a whole blood transfusion. In uncontrolled hemorrhage, crystalloid resuscitation is often more conservative and is referred to as "permissive hypotension." The goal of "permissive hypotension" would be to provide enough perfusion pressure to vital organs such that function is maintained while keeping blood pressure below the normal range in the hope that clot formation will not be disrupted. Whole blood and fresh frozen plasma in addition to aminocaproic acid are indicated in most horses with severe uncontrolled hemorrhage.

SUMMARY

Blood transfusion is a life-saving treatment for severe hemorrhage in horses. No precise HCT serves as a transfusion trigger; however, an HCT < 15%, lack of appropriate clinical response, or significant improvement in plasma lactate following crystalloid resuscitation and loss of 25% or more of blood volume is suggestive of the need for whole blood transfusion. Mathematical formulas may be used to estimate the amount of blood required for transfusion following severe but controlled hemorrhage, but these are not very accurate and, in practice, transfusion volume should be approximately 40% of estimated blood loss.

KEY POINTS

Modest hemorrhage, <15% of blood volume (<12 mL/kg), can be fully compensated by physiological mechanisms and generally does not require fluid or blood product therapy. More severe hemorrhage, >25% of blood volume (> 20 mL/kg), often requires crystalloid or blood product replacement, while acute loss of greater than 30% (>24 mL/kg) of blood volume may result in hemorrhagic shock requiring resuscitation treatments Uncontrolled hemorrhage is a common occurrence in equine practice, and is most commonly associated with abdominal bleeding (eg, uterine artery rupture in mares). If the hemorrhage can be controlled such as by ligation of a bleeding vessel, then initial efforts to resuscitate the horse should focus on increasing perfusion pressure and blood flow to organs as quickly as possible with crystalloids or colloids while assessing need for whole blood transfusion. While fluid therapy is being administered every effort to physically control hemorrhage should be made using ligatures, application of compression, surgical methods, and local hemostatic agents like collagen-, gelatin-, and cellulose-based products, fibrin, yunnan baiyao (YB), and synthetic glues Although some synthetic colloids have been shown to be associated with acute kidney injury in people receiving resuscitation therapy,²⁰ this undesirable effect in horses has not been reported.

Collection and administration of blood products in horses: Transfusion indications, materials, methods, complications, donor selection, and blood testing

BACKGROUND

Blood transfusion is a lifesaving treatment for horses with acute hemorrhage and other causes of anemia. Transfusions improve oxygen delivery to the tissues via increased blood volume and hemoglobin concentration. Certain aspects of equine blood transfusion are challenging, especially in the field situation, and practitioners may be unfamiliar or feel overwhelmed with the process. An understanding of the indications, materials, methods, and techniques as well as donor selection and possible complications will help practitioners successfully implement blood transfusion in clinical practice.

PROCEDURES

Blood transfusion involves several steps including appropriate donor selection, cross-matching, blood collection, and administration, as well as monitoring and handling of transfusion reactions. Guidance for each of these steps are detailed in this review.

SUMMARY

Blood transfusion is an effective and often lifesaving treatment for managing diseases of blood loss, hemolysis, and decreased RBC production. Equine practitioners require a thorough understanding of the indications for blood transfusion, the immunological principles behind compatibility testing and transfusion reactions, and the technical skills to aseptically collect and administer blood products KEY POINTS: Equine practitioners require a thorough understanding of the indications for blood transfusion, the immunological principles behind compatibility testing and transfusion reactions, and the technical skills to aseptically collect and administer blood products. Because there are over 400,000 possible equine RBC phenotypes, no universal donor exists, and some blood type incompatibilities are likely between any donor and recipient. Therefore, prior to any blood transfusion, donor and recipient blood should be cross-matched Inadequate delivery of oxygen (Do₂ ) to the tissues, resulting from low hemoglobin (Hb) concentration, is the most important indication for blood transfusion Neonatal isoerythrolysis most commonly occurs following an anamnestic response in late gestation; it rarely occurs following a primary exposure because the immune response is not strong enough to produce clinically significant alloantibody titers.

Immune response to allogeneic equine mesenchymal stromal cells

Background

Mesenchymal stromal cells (MSCs) are believed to be hypoimmunogeneic with potential use for allogeneic administration.

Methods

Bone marrow was harvested from Connemara (n = 1), Standardbred (n = 6), and Thoroughbred (n = 3) horses. MSCs were grouped by their level of expression of major histocompatibility factor II (MHC II). MSCs were then sub-grouped by those MSCs derived from universal blood donor horses. MSCs were isolated and cultured using media containing fetal bovine serum until adequate numbers were acquired. The MSCs were cultured in xenogen-free media for 48 h prior to use and during all assays. Autologous and allogeneic MSCs were then directly co-cultured with responder leukocytes from the Connemara horse in varying concentrations of MSCs to leukocytes (1:1, 1:10, and 1:100). MSCs were also cultured with complement present and heat-inactivated complement to determine whether complement alone would decrease MSC viability. MSCs underwent haplotyping of their equine leukocyte antigen (ELA) to determine whether the MHC factors were matched or mismatched between the donor MSCs and the responder leukocytes.

Results

All allogeneic MSCs were found to be ELA mismatched with the responder leukocytes. MHC II-low and universal blood donor MSCs caused no peripheral blood mononuclear cell (PBMC) proliferation, no increase in B cells, and no activation of CD8 lymphocytes. Universal blood donor MSCs stimulated a significant increase in the number of T regulatory cells. Neutrophil interaction with MSCs showed that universal blood donor and MHC II-high allogeneic MSCs at the 6 h time point in co-culture caused greater neutrophil activation than the other co-culture groups. Complement-mediated cytotoxicity did not consistently cause MSC death in cultures with active complement as compared to those with inactivated complement. Gene expression assays revealed that the universal blood donor group and the MHC II-low MSCs were more metabolically active both in the anabolic and catabolic gene categories when cultured with allogeneic lymphocytes as compared to the other co-cultures. These upregulated genes included CD59, FGF-2, HGF, IDO, IL-10, IL-RA, IL-2, SOX2, TGF-β1, ADAMSTS-4, ADAMSTS-5, CCL2, CXCLB/IL-8, IFNγ, IL-1β, and TNFα.

Conclusions

MHC II-low MSCs are the most appropriate type of allogeneic MSC to prevent activation of the innate and cell-mediated component of the adaptive immune systems and have increased gene expression as compared to other allogeneic MSCs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02624-y.

Circulating Wnt Ligands Activate the Wnt Signaling Pathway in Mature Erythrocytes

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Investigation of erythrocyte antigen frequencies in draft horse populations in Japan to assess blood donor suitability

Erythrocyte alloantigen frequencies of draft horses in Japan were investigated to assess blood donor suitability for transfusion. Here, 148 Japanese draft, 69 Percheron, and 65 Breton horses were blood-typed and subjected to an indirect antiglobulin test. Regarding the major immunogenic factors, the rates of Aa- and Qa-negative horses ranged from 0.35 to 0.49 and from 0.82 to 1.00, respectively. The rate of alloantibody-positive horses ranged from 0.12 to 0.35. Although the prevalence of alloantibodies in these horses was higher than that expected naturally, the rates of Aa- and Qa-negative horses were higher than those of some breeds reported previously. The current draft horse population could provide potential candidates for donors, and the obtained information may contribute to the selection of a safe donor for transfusion.

Preliminary Investigation of Bovine Whole Blood Xenotransfusion as a Therapeutic Modality for the Treatment of Anemia in Goats

Anemia requiring whole blood transfusion for appropriate treatment is a common clinical presentation of caprine patients to veterinary practitioners; however, identifying suitable blood donors in goat herds can be challenging. In other veterinary species, the practice of xenotransfusion, where blood from 1 species is transfused to another, is used in emergency settings. Due to their ability to donate large volumes of whole blood, cattle could be an ideal source for xenotransfusion of goats. In this study 2 healthy goats were transfused with bovine whole blood. The goats were then monitored for adverse effects and the presence of bovine erythrocyte post-xenotransfusion. Afterward, 15 caprine–bovine combinations were evaluated for compatibility via cross-matching. Both goats tolerated xenotransfusion, although transient reactions were observed. Of the 15 cross-match combinations, 11 of the major cross matches were compatible, and all minor cross matches were also compatible. While future work is necessary to refine this technique, xenotransfusion of goats with cattle blood may be a therapeutic modality for the treatment of caprine anemia.

Prevalence of Ca Blood Type and Alloantibodies in a Population of Horses from Italy

Simple Summary

Indications for whole blood transfusion in equine critical care include severe anemia from surgical blood loss or acute hemorrhage, hemolysis and neonatal isoerythrolysis. In horses, as in other animals, transfusions are associated with a number of inherent risks such as transfusion reactions. Pretransfusion screening and blood typing are indicated to minimize the risk of incompatible red cell transfusions. Equine blood types include seven systems, namely A, C, D, K, P, Q, and U. The major RBC antigens that warrant identification before packed RBC or whole blood transfusions in horses are Ca and Aa. The frequencies of blood groups can vary from one population to another and from one breed to another. In some situations where testing compatibility is not possible, such as in rural practice, the knowledge of the breed blood type frequencies may help selecting the best donor candidate. The aims of this study were to: estimate the prevalence of Ca blood type in horses from northern Italy; estimate the association between Ca blood type sex and breed of horse; estimate the prevalence of anti-Ca alloantibodies in Ca− horses. The prevalence of the Ca+ blood type was 79.1%. No significant association was found between blood type Ca and sex. The total number of Ca− samples with detectable anti-Ca alloantibodies was 7/23 (30.4%).

Abstract

A knowledge of the blood groups and alloantibodies present is essential for the safe transfusion of blood products in horses. Pre-transfusion screening and blood typing minimizes the risk of incompatible RBC transfusions and prevents immunization of the recipient against incompatible RBC antigens. The frequencies of blood groups can vary among different breeds. Knowledge of a breed’s blood group prevalence can be very useful for identifying the best blood donors during transfusion in clinical practice. The aims of this study were to estimate the prevalence of the Ca blood type in horses from Italy using a monoclonal immunocromatographic method and to estimate the prevalence of anti-Ca alloantibodies in Ca− horses using agglutination on gel technique. Ca blood type was determined on 110 whole blood samples. The prevalence of the Ca+ blood type was 79.1%. This study also provides data about the prevalence of Ca+ blood group in Italian Saddle Horses (77,3%) and Dutch Warmblood (58,3%). No significant association was found between Ca blood type and sex with 79.5% and 78.8% of females and males testing Ca+, respectively. The total number of Ca− samples with detectable anti-Ca alloantibodies was 7/23 (30.4%).

Agreement of stall-side and laboratory major crossmatch tests with the reference standard method in horses

Background

Crossmatching is used to prevent life‐threatening transfusion reactions in horses. Laboratory methods are laborious and technically challenging, which is impractical during emergencies.

Hypothesis/Objectives

Evaluate agreement between a stall‐side crossmatch kit (KIT) and a laboratory method (LAB) in horses with known and unknown blood types.

Animals

Twenty‐four blood‐typed and alloantibody‐screened healthy adult horses (Aim 1) and 156 adult horses of unknown blood type (Aim 2).

Methods

Prospective, blinded study. Expected positive (n = 35) and negative (n = 36) crossmatches among 24 antibody and blood‐typed horses were used to determine sensitivity and specificity of KIT and LAB against the reference method. Agreement in 156 untyped horses was evaluated by reciprocal crossmatch (n = 156).

Results

Sensitivity (95% confidence interval [CI]) for LAB and KIT compared with expected reactions was 77.1% (59.9%‐90.0%) and 91.4% (77.0%‐98.2%), and specificity 77.8% (60.9%‐89.9%) and 73.5% (55.6%‐87.1%), respectively. The KIT was 100% sensitive for Aa reactions; LAB was 100% sensitive for Qab; and both were 100% sensitive for Ca. Cohen's κ agreement for LAB and KIT with expected positive and negative reactions (n = 71) was moderate (0.55 [0.36‐0.74]) and substantial (0.65 [0.47‐0.82]), respectively. Agreement was fair comparing LAB with KIT in Aim 1 (0.30 [0.08‐0.52]) and in untyped horses in Aim 2 (0.26 [0.11‐0.41]).

Conclusions and Clinical Importance

Agreement between KIT and LAB with expected reactions was blood type dependent. Performance of both methods depends on blood type prevalence.

Blood type and breed-associated differences in cell marker expression on equine bone marrow-derived mesenchymal stem cells including major histocompatibility complex class II antigen expression

BACKGROUND

As the search for an immune privileged allogeneic donor mesenchymal stem cell (MSC) line continues in equine medicine, the characterization of the cells between different sources becomes important. Our research seeks to more clearly define the MSC marker expression of different equine MSC donors.

METHODS

The bone marrow-derived MSCs from two equine breeds and different blood donor-types were compared over successive culture passages to determine the differential expression of important antigens. Eighteen Thoroughbreds and 18 Standardbreds, including 8 blood donor (erythrocyte Aa, Ca, and Qa antigen negative) horses, were evaluated. Bone marrow was taken from each horse for isolation and culture of MSCs. Samples from passages 2, 4, 6, and 8 were labelled and evaluated by flow cytometry. The cell surface expression of CD11a/18, CD44, CD90 and MHC class II antigens were assessed. Trilineage assays for differentiation into adipogenic, chondrogenic and osteogenic lines were performed to verify characterization of the cells as MSCs.

FINDINGS

There were significant differences in mesenchymal stem cell marker expression between breeds and blood antigen-type groups over time. Standardbred horses showed a significantly lower expression of MHC class II than did Thoroughbred horses at passages 2, 4 and 6. CD90 was significantly higher in universal blood donor Standardbreds as compared to non-blood donor Standardbreds over all time points. All MSC samples showed high expression of CD44 and low expression of CD11a/18.

CONCLUSIONS

Universal blood donor- type Standardbred MSCs from passages 2-4 show the most ideal antigen expression pattern of the horses and passages that we characterized for use as a single treatment of donor bone marrow-derived MSCs. Further work is needed to determine the significance of this differential expression along with the effect of the expression of MHC I on equine bone marrow-derived MSCs.

Modified stall-side crossmatch for transfusions in horses

Background

After‐hours or out‐of‐clinic crossmatches are often limited by the lack of access to specialized material and technical expertise.

Hypothesis/Objectives

The goal was to adapt a stall‐side crossmatch test for pretransfusion evaluation in horses.

Animals

Twelve healthy mares (plasma and blood donors, teaching mares).

Methods

In a prospective study, blood from 12 mares was used to compare the results of 132 crossmatches performed with a rapid gel assay to crossmatches performed with a microgel column assay, and with predicted compatibilities based on blood types and detection of antibodies at a reference laboratory (microplate assay). The rapid gel assay protocol for dogs was adapted to decrease the formation of rouleaux that initially precluded equine erythrocytes migration through the gel.

Results

There was a good agreement between the rapid gel assay and the microgel assay as well as with the predicted compatibilities (κ > .6 for both). Agreement was higher between the microgel assay and the predicted compatibilities (κ = .8). The rapid gel assay failed to detect 6 predicted Aa incompatibilities (agglutinins‐related), 3 of which were also not detected with the microgel assay.

Conclusions and Clinical Importance

Based on these results, the modified rapid gel assay could be useful in settings when access to the microgel assay is not available. Discrepancies between both gel techniques and predicted compatibilities were most often low‐grade agglutination, which warrants further investigation to assess their clinical importance.

Comparison of Tube, Gel, and Immunochromatographic Strip Methods for Evaluation of Blood Transfusion Compatibility in Horses

Background

Assessment of blood compatibility, typically by tube agglutination (TUBE) and hemolysis crossmatch or, less commonly, by blood typing and alloantibody screening, often is performed before blood transfusion in horses. In contrast, gel column (GEL) and immunochromatographic strip (STRIP) techniques are preferred for compatibility testing in dogs and cats.

Objective

To determine the accuracy of novel and standard crossmatch and typing methods.

Animals

Thirty‐eight healthy horses, previously blood typed and alloantibody screened.

Methods

TUBE and GEL crossmatches were performed on 146 different recipient‐donor pairs with 56 incompatible TUBE crossmatches. Crossmatches were compared by nonparametric area under the curve of receiver operating characteristic (AUC‐ROC) analyses. Horses also were blood typed by the novel immunochromatographic Ca typing STRIP.

Results

Compared to TUBE crossmatch, GEL had excellent accuracy for agglutination (AUC‐ROC = 0.903), but marginal accuracy for hemolysis (AUC‐ROC = 0.639). Compared to macroscopic TUBE, microscopic TUBE had excellent accuracy for agglutination (AUC‐ROC = 0.912). The predicted crossmatch compatibility based on blood type and alloantibody assay showed excellent accuracy compared to TUBE and GEL (AUC‐ROC = 0.843 and 0.897, respectively). However, there were more recipient‐donor pairs identified as incompatible by both TUBE and GEL than predicted by blood type and antibody screen, suggesting the presence of unidentified alloantibodies. A Ca typing STRIP exhibited 100% sensitivity and specificity for the 35 Ca+ and 3 Ca‐ horses tested.

Conclusions and Clinical Relevance

Gel column crossmatch and Ca typing immunochromatographic strip are simple and accurate methods to evaluate clinical blood compatibility.