The Change Of T Cell Subsets In Peripheral Blood Of Spinal Cordinjured Rats And Culture And Identification Of MBP Activated T Cells Of Rats

Objective To culture the myelin basic protein (MBP) specific T lymphocytes in SD rats, and identify their characterization of phenotype and cytokine profiles; Preparation of spinal cord injury (SCI) rat model and collected the peripheral blood at different time before and after SCI and detect its phenotypic characteristics, so as to understand the changes of of T lymphocytes subsets and immune activity in different period of SCI.Methods The SD rats were immunized with MBP; the draining lymph nodes were collected and made into single cell suspension. The cells were cultured in RMPI 1640 medium and stimulated repeatedly with MBP to produce MBP specific T lymphocytes (MBP-T). Then, their reactivity to MBP stimulation was measured using 3H-thymidine 3H-TdR) incorporation, the phenotype and cytokine profiles were determined using by flow cytometry; Rat model of SCI was established by using New York University impactor. The peripheral blood was collected from the tail per-SCI, at the second days, fourth days, seventh days, fourteenth days and twenty-first days after SCI. T ymphocyte phenotypes and subsets were detected by flow cytometry.Results When the presence of MBP antigen,3H-TdR incorporation of MBP-T cells increased obviously. Flow cytometry showed that MBP-T cells were mainly CD3+ CD4+T lymphocytes (98%), and could produce interferon-γ (IFN-γ) and interleukin-10(IL-10). The CD3+　T lymphocytes and CD4+T lymphocytes were reduced after the SCI (P<0.05), The CD3+T lymphocytes and CD4+T lymphocytes sells returned to pre SCI levels at seventh day; The CD8+T lymphocytes returned to pre SCI levels at fourteenth day. The ratio of CD4+/CD8+　increased at fourth day (P<0.05) and reduced at twenty-first day (P<0.05); CD4+CD25high Treg lymphocytes increased significantly at second day (P<0.01), It was reduced significantly after fourth days(P<0.01); CD8+CD28+lymphoc-ytes reduced at second day and fourth day (P<0.05, P<0.01), return to pre SCI levels at seventh day, It was significantly higher at twenty-first day than pre SCI level (P<0.01); CD8+CD28- lymphocytes were reduced significantly in seven days after SCI(P<0.05) and returned to pre SCI levels at fourteenth day.Conclusion (1) The cells collected from the draining lymph nodes of MBP immunized SD rats could be amplified into MBP-T cells in vitro. The phenotypes of these cells were mainly CD3+CD4+, and showed the Thl and Trl cytokine profiles.(2) The spinal cord injury may cause inhibition of cellular immunity and nonspecific immunity, lead to the immune function declined;(3) The CD4+CD25high Treg cells may be important factor is which caused the decreasing of total T cells,CD4+T lymphocytes and CD8+T lymphocytes in peripheral blood after spinal cord injury;(4) The cytokines released by immune inflammation cells after SCI have more powerful inhibitory effect on CD8+T lymphocytes than CD4+T lymphocytes;(5) Reducing CD8+CD28+lymphocytes and CD8+CD28- lymphocytes in peripheral blood after SCI can cause impaired of immune surveillance functions and scavenging capacity has decrease to virus, tumor cells and other foreign antigens.