Although intervertebral disc herniation and associated sciatica is a common disease, its molecular pathogenesis is not well understood. Immune responses are thought to be involved. This study provides direct evidence that even non-degeneratednucleus pulposus(NP) cells elicit immune responses. Anin vitrocolony forming inhibition assay demonstrated the suppressive effects of autologous spleen cells on NP cells and anin vitrocytotoxicity assay showed the positive cytotoxic effects of natural killer (NK) cells and macrophages on NP cells. Non-degenerated rat NP tissues transplanted into wild type rats and immune-deficient mice demonstrated a significantly higher NP cell survival rate in immune-deficient mice. Immunohistochemical staining showed the presence of macrophages and NK cells in the transplanted NP tissues. These results suggest that even non-degenerated autologous NP cells are recognized by macrophages and NK cells, which may have an immunological function in the early phase of disc herniation. These findings contribute to understanding resorption and the inflammatory reaction to disc herniation.