Single-cell transcriptomic analysis reveals transcriptional and cell subpopulation differences between human and pig immune cells

The pig is a promising candidate for xenotransplantation. Understanding the differences between human and swine immune systems is critical for addressing xeno-transplant rejection and hematopoietic reconstitution. We performed single-cell RNA-seq on human and pig immune cells. High oxidative phosphorylation, HIF-1, glycolysis, and lysosome-related gene expressions in pig CD14+ monocytes were observed, whereas pig CD14+ monocytes exhibited lower levels of cytokine receptors and JAK-STAT-related genes. Pig activated CD4+T cells decreased cell adhesion and inflammation, while enriched for migration and activation processes. Porcine GNLY+CD8+T cells reduced cytotoxicity and increased proliferation compared with human GNLY+CD8+T cells. Pig CD2+CD8+γδT cells were functionally homologous to human CD2+CD4+ γδT cells. Pig CD2-CD8-γδT cells expressed genes with quiescent and precursor characteristics, while CD2-CD8+γδT cells expressed migration and memory-related molecules. Pig CD24+ and CD5+B cells are associated with inflammatory responses. Our research with integrated scRNA-seq enables a deeper understanding of the development and function of porcine immune cells. Pig blood was collected from the anterior vena cava, and human blood was collected from the median cubital vein. PBMCs were isolated by Ficoll gradient centrifugation.