The Effect Of T Cells On The Survival Of Injured RGCs In Vitro

Background and ObjectiveThe protecting or damaging function of lymphocytes on the injury of central nervous system(CNS) has not been identified. Lymphocytes, the important component of immune system,recognize, response, and clear up foreign invaders and maintain homeostasis. Injured optic nerve(ON) and other central nerve just appear transient axon sprouting and injury usually leads to theloss of corresponding neurons. A great deal of evidence reported that inflammatory response of Tcells and macrophages after CNS injury had damaging effect under certain circumstances. Butsome indicated that activated T ceils prevent injured RGC axons from secondary degeneration,and spontaneous T cell response to injury was also suggested to play a role in protecting injuredRGCs in experimental autoimmune encephalomyelitis (EAE)-resistant F344 but not vulnerableLewis rats. Then the study of vaccination about protecting CNS injury was carried out, on whichothers hold opposite views. About our early research in vivo, we found that F344 T cells inhibitinjured RGC survival of normal rats but Lewis T cells did not influence RGC survival. The exactroles of T cells on the injured RGC survival of two different strains are still controversial. In this,we examined the effect of lymphocytes especially T cells on the RGC survival after ON axotomybetween F344 and Lewis rats. one-week after culture. Then the amount of viable RGCs was counted under fluorescencemicroscope. We also collected the normal or co-cultured lymphocytes for flow cytometry andanalysed changes in percentage of CD3~+, CD4~+, CD8~+, CD25~+ and CD62L~+ cells of F344 andLewis rats under all intervention conditions.Results1. The effects of lymphocytes and lymphocyte medium on RGC survival of ON injurednormal rats in vitro1) In F344 retinas co-cultured with lymphocytes and lymphocyte medium, the amount of theRGCs was decreased significantly and which in former group was more than the latter one.But Lewis RGC numbers did not changed statistically among these groups.2) In F344 retinas cultured by lymphocytes with transwell, the quantity of RGCs was similarwith control group.3) When lymphocytes obtained from axotomy rats were cultured with retinas, the number ofRGCs in F344 was similar with control, but which in Lewis was fewer than control.4) In retinas co-cultured with allogenic lymphocytes and lymphocyte medium, RGC numbers inlymphocyte medium group of Lewis is larger than control and lymphocytes group. Therewere no statistical changes between F344 groups.2. The effects of lymphocytes and lymphocyte medium on RGC survival of ON injuredthymectomied rats in vitro1) The result about assessment T cells in peripheral blood was that no CD3~+ cells appeared inthymectomied rats.2) When thymectomied Lewis retinas co-cultured with lymphocytes, the amount of the RGCsurvival was diminished obviously compared with control and also lower than lymphocytemedium group. But they did not influence on thymectomied F344 RGC survival.3. Assessment cultured lymphocytes of rats in FCM1) Among lymphocyte cultures, the percentage of T cells was about 60%.2) Among T cells, the percentage of CD4~+ cells in F344 was 44.3% and increased by 6.6% after cultured with retina; the percentage in Lewis was 61.1% and increased by 7.5% after culturedwith retina. The ratio of CD8~+ cells in F344 was 31.9% and decreased by10% after culturedwith retina; the ratio in Lewis was 19.4% and decreased by 15% during co-culture.3) The proportion of CD25~+ in CD4~+ T cells in F344 was 4.9% and increased by 2% aftercultured with retina; but it in Lewis was 4.4% and decreased by 2% after cultured with retina4) The percentage CD62L~+ cell in F344 lymphocytes was 39.6%, which increased by 7% whenco-cultured with F344 retina and decreased by 3% when cultured with Lewis retina.Conclusion1. T cells under different conditions had different effects on RGC survival of ONinjured normal rats in vitro.1) Normal F344 but not Lewis T cells had detrimental effects on RGC survival afteraxotomy.2) The injury activated T cells ofF344 rats did not influence on the RGC survival, but whichin Lewis inhibited cell survival.2. T cells of two different strains appeared different roles on RGC survival of ONinjured rats under normal or thymectomy conditions in vitro, suggesting differentvulnerability of RGCs under different conditions.1) F344 but not Lewis T cells inhibit normal rat injured RGC survival.2) Lewis but not F344 became deleterious on injured RGC survival in thymectomied rats.3. T cells played detrimental effect on the retinas by cell-to-cell effect and secretionmolecules, of which the former was predominant.4. The deleterious effect of F344 T cells on RGCs may be related to the functions ofTreg and CD62L~+ subpopulations of T cells.