PRG2 and intervertebral disk degenerative disorder: To further investigate the effect of the immune response on IDD pathogenesis, we performed blood cell subpopulation analysis and revealed that blood cells could be further divided into MCs (CXCL8, IL-1B, and CCL3) (18), T cells (PTPRC, MT1X and CST7) (19) and CMPs (TPSB2, PRG2, TPSAB1) (Figures 3A, C).