Studies of innate immune systems against human cells

- The alternative pathway for pig complement reacts with human cells.
- Pig serum contains natural antibodies, IgM and IgG, to human cell.
- Pig NK cells and monocyte/macrophage can injure human cells.
- Pig innate immunological systems are able to recognize and injure human cells.

BackgroundPigs are frequently used as animal models for experiments in the surgical field, including allo- and xeno-transplantation. Regeneration studies, including studies dealing with human- and monkey-induced pluripotent stem cells (iPSC), have gradually progressed, with pigs sometimes being used as the scaffold. However, the immunological response of pigs against humans, especially innate immunities, remain unclear. This study reports on a comprehensive study of pig innate immunity against humans.MethodsHemolytic complement activity of pig serum was measured using a microtitration technique. The pig natural anti-human antibody (Ab) was examined using human peripheral blood mononuclear cells (PBMC). The reaction of pig natural killer (NK) cells and monocytes/macrophages against human cells was also assessed.ResultsMost of the pig complement titers were measured based on methods used in human complement assays. The alternative pathway for pig complement reacts with human cells, indicating that pig complement can react with human cells. Pig serum contains relatively high levels of natural antibodies, IgM and IgG, to human PBMC. Furthermore, the killing of NK cells- and monocyte/macrophage-mediated human cells was clearly confirmed.ConclusionThe collective findings indicate that the pig innate immunological systems, not only serum but also cellular factors, are able to recognize and injure human cells.