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.