title: [Function of CD4⁺ T cells in CD8⁺ T cell mediated rejection].
abstract: OBJECTIVE
  To explore the absence of CD4⁺ T cells, naїve CD8⁺ T cells and memory CD8⁺ T (CD8⁺ Tm) cells in the role of mediated acute graft rejection and discuss its possible mechanism.
  
  
  METHODS
  Mice were randomly divided into three groups (n = 6). And at Day 2 pre-transplantation, two types of cells (CD8⁺ T cells (CD8⁺ T group) or CD8⁺ Tm cells (CD8⁺ Tm group)) were transferred into nude mice (1 × 10⁶ cells/one mice) via tail vein injections. At Day 0, C57BL/6 mice were used as donors for cervical heterotopic heart transplantation with nude mice as recipients (control group without transplantation). The survival of transplants was recorded and the mean survival time (MST) calculated. Then at Day 10 post-transplantation, the recipient's heart graft, spleen and lymph node were collected for immunological detections. And the ratio of CD8⁺ cells in spleen and lymph nodes and serum levels of IL-2 in recipients were tested.
  
  
  RESULTS
  In the group of adoption naїve CD8⁺ T cells and heart grafting, there was no occurrence of acute graft rejection (MST>60 d) , while in the group of adoption memory CD8⁺ Tm cells and heart grafting, there was serious rejection(MST: (8.9 ± 0.5) d) (P < 0.01). In the group of adoption naїve CD8⁺ T cells and heart grafting, cell proliferation of transferred CD8⁺ T cells in spleen and lymph node showed no statistical difference compared with non-transplanted mice (2.70% ± 0.08% vs 2.27% ± 0.22%, 3.41% ± 0.25% vs 2.80% ± 0.62%, both P > 0.05). However, in the group of adoption CD8⁺ Tm cells and heart grafting, cell proliferation of transferred CD8⁺ Tm cells in spleen and lymph node showed significant statistical difference with non-transplanted mice (9.65% ± 0.60% vs 2.12% ± 0.18%, 11.15% ± 1.35% vs 3.03% ± 0.10%, both P < 0.01). The levels of IL-2 secretion before and after transplantation, naїve CD8⁺ T cells showed no statistical difference (P > 0.05), CD8⁺ Tm cells showed significant statistical difference (P < 0.01).
  
  
  CONCLUSIONS
  In the absence of CD4⁺ T lymphocyte helping, naїve CD8⁺ T cells can not activate and show immunological functions. But memory CD8⁺ T can activate, proliferate and generate effector cells to mediate immune response.
authors.affiliation: College of Clinical Medicine, Xiamen University, Xiamen 361003, China.
authors.forename: Chun
authors.initials: C
authors.lastname: Li
authors.forename: Yingying
authors.initials: Y
authors.lastname: Lin
authors.forename: Chang
authors.initials: C
authors.lastname: Gao
authors.affiliation: Transportation Institute of Xiamen University, Xiamen 361003, China,Email: oti@xmu.edu.cn.
authors.forename: Zhongquan
authors.initials: Z
authors.lastname: Qi
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes; D018414:CD8-Positive T-Lymphocytes; D006084:Graft Rejection; D016027:Heart Transplantation; D007376:Interleukin-2; D051379:Mice; D008810:Mice, Inbred C57BL; D008819:Mice, Nude; D013154:Spleen
chemical_list: D007376:Interleukin-2