Immune cell distribution and immunoglobulin levels change following sciatic nerve injury in a rat model

OBJECTIVES To investigate the systemic and local immune status of two surgical rat models of sciatic nerve injury, a crushed sciatic nerve, and a sciatic nerve transection. MATERIALS AND METHODS Twenty-four adult male Sprague-Dawley rats were randomly divided into three groups: sham-operation (control group), sciatic nerve crush, and sciatic nerve transaction. Sciatic nerve surgery was performed. The percentage of CD4(+) cells and the CD4(+)/CD8+ratio were determined by flow cytometry. Serum IgM and IgG levels were analyzed by ELISA. T-cells (CD3) and macrophages (CD68) in sciatic nerve tissue sections were identified through immunohistochemistry. RESULTS Compared to sham-operated controls, in rats that underwent nerve injury, the percentage of CD4(+) cells and the CD4(+)/CD8(+) ratio in the peripheral blood were significantly decreased 7 days after surgery, serum IgM levels were increased 14 days after surgery, and serum IgG levels were increased 21 days after surgery. There were a large number of CD3(+) cells and a small number of CD68(+) cells in sciatic nerve tissue sections 21 days after surgery, indicating T-cell and macrophage activation and infiltration. Local IgG deposition was also detected at the nerve injury site 21 days after surgery. CONCLUSION Rat humoral and cellular immune status changed following sciatic nerve injury, particularly with regard to the cellular immune response at the nerve injury site.