The Immunological Effect Induced By Different Antigens In The Spleen And Thymus Of Mice

Background and objectiveThe thymus is the central immune organ of mammals, which provides a rigid and complex microenvironment for T lymphocyte derived of bone marrow development, differentiation and maturation. Then T cells migrate to the peripheral immune organs involving in immune response.The theory of immunology theory considers that T cells interact with thymic stromal cells expressing MHC molecular during development, It is screened that mature T lymphocytes response to the external antigen and tolerance to self-antigen through positive selection and negative selection. According to the traditional theory of the induction of central tolerance, peripheral tolerance on allogeneic antigens can be induced when T cells are exposed the same antigen during development in the thymus. At the same time, blood-thymus barrier proved a stable microenvironment for T cell development, foreign macromolecular substances and antigens can not entry the thymus easily, so the immune mechanism of thymus was not attentioned before.The spleen is the peripheral immune organ of mammals.It plays the immune response when the external antigens invading the body.Blood-spleen barrier has a strong selectivity for antigen property rather than complete antigen size,But if it will have an effect on the microenvironment of thymus after immune response occurred in spleen, it is rarely reported at present.The study first immuned C57BL/6 mouse using the AFP as exogenous antigen molecules,then observed thymus and spleen’s immune status.Secondly we injected human liver cancer cell (HepG2)as heterologous antigen cells into C57BL/6 mouse thymus,then observed if the thymic exist immune response and the fate of heterologous antigen.Methods1.Exogenous antigen molecules effects on mice spleen and thymus after peripheral immune1) the peripheral AFP immune in C57BL/6 mouse2) mouse thymus tissue weight and thymus cells changes3) the production of paraffin section and HE dyeing observation2. Exogenous antigen cells induced immune response in mice thymus1) Analysis of mouse thymus development situation2) HepG2 cultrured and DiI Labeling3) intrathymic injection and anatomic observation4) the production of paraffin section and HE dyeing observation5) the production of paraffin section and direct immuno fluorescence observationResultsThe first part1.An immune mouse spleen and thymus weight and lymphocyte count ratio increased slightly in comparison with control group, but the overall change is not very obvious.two imunizations group spleen weight and total lymphocyte count had obvious difference in comparison with control and an immune group.Its weight is 2.6 times more than control group,the total number of lympocytes is 10 times more than the control group.No significant difference between two imunizations group thymus weight and lymphocyte countand.2. An immune mice spleen white pulp and red pulp ratio similar to that in the control group,and two imunizations group significantly increased the proportion of white pulp.The second part1.The thymus has been increased from bith to adolescence in volume and weight,peaked at about 6 weeks.later the thymus begins to shrink in volume and weight.2. HepG2 cells were all marked, a strong red fluorescence in the cell under the excitation of the green fluorescence.3. Thymus at different time points showed that tumor tissue, liver cancer cells were injected successfully.4.The thymus immune rejection of xenogeneic antigen, tumor tissue was completely surrounded by thymic epithelial cells、infiltration of lymphocytes, tumor tissue necrosis at last during 3-14days.5. The initial formation of the tumor tissue, the surrounding gathered a large number of T cells in, a small number of T cell invasion to the tumor area about 5 days, A lot of tumor tissue mass death about 7 days, Lymphocyte infiltration area has a hollow shape plaque was observed in tumor mass centre.Conclusions1.AFP immunization of mice after 18 weeks, mice in the static recovery state, once again. exposed to the same antigen, mice spleen occurs strong immune response, and almost no immune response of thymus.2. HepG2 tumor cells rejected in thymus can form tumor tissue during 5 to 14 days, then tumor tissue can be infiltrated by lymphoctes and macrophages,and,ultimately be eliminated.xenogeneic antigen can cause immune rejection in mouse thymus,It is determined by characteristics of the thymic microenvironment.