Blood groups have been well characterized in humans and some domestic animals. However, blood group information for non-domestic species is scarce. The purpose of this study was to evaluate red blood cell (RBC) antigen diversity and the presence of alloantibodies in killer whales (Orcinus orca). Major and minor crossmatch reactions were performed on blood samples collected from twenty killer whales of varying relatedness. Three groups of whales carried the same combination of antigens on their RBCs, and the remaining 10 whales (50%) had a unique RBC antigen phenotype. The same combination of alloantibodies was detected in seven animals comprising two groups of whales. Of the remaining thirteen animals, seven (35%) whales had a unique alloantibody phenotype and six (30%) whales had no detectable alloantibodies. Despite the relatively small sample size, some evidence (p < 0.10) of both positive and negative selection of RBC antigens was detected within both maternal and paternal lineages. Our findings show that killer whales have highly diverse red blood cell antigen phenotypes and some pre-existing alloantibodies. This information has important implications for transfusion medicine of killer whales and other delphinids. The determination of lineage-associated RBC antigen patterns has the potential to help determine paternal relatedness, where mitochondrial DNA analysis is not useful, and to illuminate ecotype distinctions of wild killer whales.
The authors thank the Veterinary Services Departments of the SeaWorld of Florida and Texas for their assistance with sample collection and processing. All samples were collected as part of the routine veterinary medicine program for killer whales housed at SeaWorld.
* Presenting author