Levels of human LIF and IFN-γ. (A) LIF curve in the serum of Group IV pigs; (B) LIF was markedly increased after hPMSCs were co-cultured with PMBCs for 24 h. **P < 0.01; (C, D) hPMSCs stimulated PBMCs to secret IFN-γ. Each spot represents one human IFN-γ secreting cell. Spots were counted using ImmunoSpot ver. 5.0.3. The spots of the positive control were too numerous to count (TNTC). *P < 0.05, **P < 0.01.