A REPORT ON BLOOD GROUPS IN PIGS

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.

Normothermic machine perfusion of ischaemically damaged porcine kidneys with autologous, allogeneic porcine and human red blood cells

In porcine kidney auto-transplant models, red blood cells (RBCs) are required for ex-vivo normothermic machine perfusion (NMP). As large quantities of RBCs are needed for NMP, utilising autologous RBCs would imply lethal exsanguination of the pig that is donor and recipient-to-be in the same experiment. The purpose of this study was to determine if an isolated porcine kidney can also be perfused with allogeneic porcine or human RBCs instead. Porcine kidneys, autologous and allogeneic blood were obtained from a local slaughterhouse. Human RBCs (O-pos), were provided by our transfusion laboratory. Warm ischaemia time was standardised at 20 minutes and subsequent hypothermic machine perfusion lasted 1.5–2.5 hours. Next, kidneys underwent NMP at 37°C during 7 hours with Williams' Medium E and washed, leukocyte depleted RBCs of either autologous, allogeneic, or human origin (n = 5 per group). During perfusion all kidneys were functional and produced urine. No macroscopic adverse reactions were observed. Creatinine clearance during NMP was significantly higher in the human RBC group in comparison with the allogeneic group (P = 0.049) but not compared to the autologous group. The concentration of albumin in the urine was significantly higher in the human RBC group (P <0.001) compared to the autologous and allogeneic RBC group. Injury marker aspartate aminotransferase was significantly higher in the human RBC group in comparison with the allogeneic group (P = 0.040) but not in comparison with the autologous group. Renal histology revealed glomerular and tubular damage in all groups. Signs of pathological hyperfiltration and microvascular injury were only observed in the human RBC group. In conclusion, perfusion of porcine kidneys with RBCs of different origin proved technically feasible. However, laboratory analysis and histology revealed more damage in the human RBC group compared to the other two groups. These results indicate that the use of allogeneic RBCs is preferable to human RBCs in a situation where autologous RBCs cannot be used for NMP.

Recombination between the S and the H blood group loci in pigs

The investigation of A-O blood group phenotypes in selected pig families confirms the existence of an S locus which specifically controls the expression of A and O alloantigens. Forty-five informative litters were scored for linkage between the S gene and the H blood group locus. The recombination frequency in 345 offspring was estimated to be 9.56% (33 cross-overs). Specific difficulties involved in the determination of A-O and H phenotypes and the importance of S and H polymorphisms for the determination of Hal genotypes are discussed.

The blood group factor Kf and allele Kae in the pig

By means of alloimmune reagents used in the indirect Coombs test and the dextran test a new factor Kf in the K bloodgroup system of pigs was found, controlled by alleles Kacf, Kacef and Kbf. A new allele Kae was also detected. The K system with 6 alleles, 11 phenotypes and 21 combinations of genotypes remains (from the genetic point of view) an open system.

Blood groups and transfusions in pigs

The blood groups of pigs are important to transplantation research because some are also important transplantation antigens and because pigs undergoing organ or hematopoietic transplantation may require transfusion support. There is considerable literature on the subject but much of it is not in transplant related journals. We will review this literature and also give some practical advice on transfusion support.

Human blood group A and H glycolipids in porcine plasma. Evidence for acquisition of the erythrocyte antigens from plasma

Human blood group A- and H-antigenic glycosphingolipids were isolated from pooled porcine plasma. The structures of the A-active hexa- and H-active pentaglycosylceramides of lactoseries (type 1 sugar chain) were the same as those in porcine erythrocytes. These results endorse biochemically the previous observations that the A and H antigens on porcine erythrocytes are taken up from plasma.

Effect of sialidase on blood group specificity of hog submaxillary glycoproteins

Hogs can be divided into three phenotypes A, H and In, depending on the ability of extracts of their submaxillary glands to inhibit the agglutination of human A cells with human anti-A, and human O cells with eel-anti-H serum. Evidence is here provided that the inactive glycoprotein, In, represents H active glycoprotein containing additional N-glycolyl neuraminic acid, which stereospecifically masks the H determinant, alpha (1 --> 2)-L-fucosyl residue.