Traditionally, macroautophagy (autophagy) is viewed as a pathway of cell survival. Autophagy ensures the elimination of damaged or unwanted cytosolic components and provides a source of cellular nutrients during periods of stress. Interestingly, autophagy can also directly intersect with, and impact, other major pathways of cellular function. Here, we will review the contribution of autophagy to pathways of antigen presentation. The autophagy machinery acts to modulate both MHCI and MHCII antigen presentation. As such autophagy is an important participant in pathways that elicit host cell immunity and the elimination of infectious pathogens.
Animals ; Antigen Presentation ; Autophagy ; HLA Antigens ; immunology ; Humans ; Thymus Gland ; cytology ; immunology

The nomenclature "embryonic lymphoid tissue inducer (LTi) cell" reflects the fundamental role of the cell in secondary lymphoid tissue organization. In addition, it is equally important in primary lymphoid tissue development as it regulates central tolerance to self-antigens in the thymus. An adult LTi cell constitutively expresses two sets of tumor necrosis factor (TNF) family members, whereas its embryonic counterpart expresses only one. The first set is lymphotoxin (LT)alpha, LTbeta, and TNFalpha, which are essential for the secondary lymphoid organogenesis during embryogenesis and for maintaining an organized secondary lymphoid structure during adulthood. The second set is OX40- and CD30-ligands, which are critical for memory T cell generation. Adult LTi cells regulate adaptive immune responses by providing LTbetaR signals to stromal cells to maintain secondary lymphoid tissue structure, and determine adaptive immune responses by providing OX40 and CD30 survival signals to activated T cells in memory T cell generation. Along with the consideration of the roles of embryonic LTi cells in primary and secondary lymphoid tissues, this review highlights the roles of adult LTi cells in secondary lymphoid tissue function.
Adult ; Animals ; Humans ; Lymphoid Tissue/cytology/embryology/*immunology ; Lymphokines/immunology/metabolism ; T-Lymphocytes, Helper-Inducer/cytology/*immunology/metabolism ; Thymus Gland/cytology/embryology/*immunology

Age Factors ; Aging ; immunology ; physiology ; Animals ; Lymphocyte Activation ; immunology ; Male ; Physical Conditioning, Animal ; physiology ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Swimming ; physiology ; Thymus Gland ; immunology

BACKGROUNDMany researches demonstrate that the secondary brain injury which is caused by autoimmune attack toward brain antigens plays an important role in surgical brain injury (SBI). Although traditional immunosuppression can reduce autoimmune attack, it will lower the body immunity. Immune tolerance, by contrast, not only does not lower the body immunity, but also could lighten autoimmunity. This study used thymus tolerance to develop an immune system that is tolerant to autologous cerebrospinal fluid (CSF) and autologous brain tissue so that autoimmune injury can be suppressed following the disruption of the blood-brain barrier, thereby reducing brain damage.

METHODSEighty experimental rabbits were divided into five groups by random number table method: 16 in SBI group (group A), 16 in SBI+CSF drainage group (group B), 16 in SBI+CSF drainage+PBS injection group (group C), 16 in SBI+CSF drainage+CSF intrathymic injection group (group D), and 16 in SBI+brain homogenate intrathymic injection group (group E). Rabbits' CSF was drained in group B; was drained and injected PBS into thymus in group C; was drained and injected CSF into thymus in group D; and was injected brain homogenate in group E. Half of the rabbits in each group were phlebotomized on 1st, 3rd, 7th, and 14th days to observe the changes in IL-l, TGF-β by ELISA test, and CD4CD25 regulatory T cells ratio by flow cytometry, and in other animals brain tissues were taken on 7th day for exploring FasL expression by RT-PCR. The least significant difference (LSD) test was used to make paired comparisons; P < 0.05 was considered statistically significant.

RESULTSThe levels of FasL, TGF-β, and the ratios of CD4CD25 regulatory T cells in groups D and E were apparently higher than those in other three groups (P < 0.05). Likewise, the levels of IL-1 in these two groups were lower than the other three groups (P < 0.05). Moreover, the ratios of CD4CD25 regulatory T cells and the levels of TGF-β in groups B and C were higher than those in group A, but the level of IL-1 was lower than that in group A (P < 0.05). There was no significant difference between groups B and C, and groups D and E.

CONCLUSIONThymic injection of CSF and brain homogenate may be able to reduce inflammation after SBI, so thymus immune tolerance may be a useful therapy to treat SBI.

Animals ; Autoantigens ; administration & dosage ; Brain ; surgery ; Brain Injuries ; etiology ; therapy ; Immune Tolerance ; physiology ; Rabbits ; Thymus Gland ; immunology

The cell surface molecule identified by a monoclonal antibody(TE-1) to human thymic epithelial cell showed the specificity for thymic epithelial cells of both the cortex and medulla. TE-1 reacted with the epithelial cells of normal thymus and thymoma in fresh frozen tissues. The antigen recognized by TE-1 was mostly confined to the cell surface membrane and arranged in reticular network with long processes between thymocytes. On immunohistochemical analysis, TE-1 did not recognize normal epithelial cells of the uterine cervix, skin and stomach, and neoplastic cells of squamous cell carcinoma and gastric adenocarcinoma, all of which were stained with anti-cytokeratin monoclonal antibody. Among the tumor cell lines tested with flow cytometry, most of epithelial and all of hematopoietic cell origin were not labeled with TE-1. In summary, TE-1 appears to be a monoclonal antibody against a surface antigen of human thymic epithelial cell that is immunohistologically different from known epithelial cell surface antigens reported so far.
Animals ; Antibodies, Monoclonal/biosynthesis/*immunology ; Antibody Specificity ; Antigens, Surface/*immunology ; Epithelium/immunology ; Fluorescent Antibody Technique ; Humans ; Immunoenzyme Techniques ; Immunoglobulin G/immunology ; Immunoglobulin Isotypes/immunology ; Mice ; Mice, Inbred BALB C ; Neoplasms/immunology ; Thymoma/immunology ; Thymus Gland/*immunology ; Thymus Neoplasms/immunology ; Tumor Cells, Cultured

For a long time, thymic function could not be monitored, as a consequence of the absence of adequate technology to detect recent thymic emigrants from naive T cells. T cell differentiation in the thymus is characterized by T cell receptor (TCR) rearrangement. During the rearrangement of TCRalpha gene segments, the deltaRec and psiJalpha rearrange to each other to delete the TCRdelta gene and form an extrachromosomal DNA circles, referred to as signal joint T cell receptor excision DNA circles (sjTRECs) or TRECs. TRECs are assumed to have a high stability, they can not multiply and consequently are diluted during T cell proliferation. It was recently suggested that quantitative detection of TRECs would allow for direct measurement of thymic output. In this review TRECs quantification is a powerful method to evaluate the thymic output function in both health and disease, including hematopoietic stem cell transplantation, hematopoietic malignancies, HIV infection and autoimmune disease, and so on is described.
Animals ; Cell Differentiation ; Cell Movement ; Gene Rearrangement, T-Lymphocyte ; HIV Infections ; immunology ; Humans ; Immunity ; Neoplasms ; immunology ; T-Lymphocytes ; physiology ; Thymus Gland ; physiology

Germ-line mutations in BRCA2 predispose to early-onset cancer. Homozygous mutant mouse, which has Brca2 truncated in exon 11 exhibit paradoxic occurrence of growth retardation and development of thymic lymphomas. However, due to its large embryonic lethality, cohort studies on the thymic lymphomas were not feasible. With the aid of Cre-loxP system, we demonstrate here that thymus-specific disruption of Brca2 allele without crossing it to p53-mutant background leads to the development of thymic lymphomas. Varying from 16 weeks to 66 weeks after birth, 25% of mice disrupted of Brca2 in the thymus died of thymic lymphomas, whereas previous report did not observe lymphomagenesis using similar Cre-loxP system. Future analysis of thymic lymphomas from these mice presented here will provide information on the cooperative mutations that are required for the BRCA2-associated pathogenesis of cancer.
Animals ; BRCA2 Protein/deficiency/*genetics ; CD4-CD8 Ratio ; Cell Separation ; Flow Cytometry ; Integrases/*genetics/immunology ; Lymphoma/*genetics/immunology/metabolism/pathology ; Mice ; Mice, Knockout ; Organ Specificity ; *Sequence Deletion ; T-Lymphocytes/enzymology/*immunology ; Thymus Gland/immunology/metabolism/pathology ; Thymus Neoplasms/*genetics/immunology/metabolism/pathology ; Tumor Suppressor Protein p53/deficiency/genetics/immunology

Maturation of T cells in thymus plays key roles in antigen-specific immune response. In maturation, thymocytes undergo positive and negative selection. The MHC restriction of T cell is determined in positive selection. The tolerance of T cells to autoantigen is acquired during negative selection. Quantitation (avidity) theory points out that difference of avidity between thymocytes and stroma cells leads to difference in the signals integrated inside cells. When the signal reaches a particular threshold, positive or negative selection takes place. In this article, the selection mechanism and the relationship between positive and negative selection are mini-reviewed.
Animals ; CD4-Positive T-Lymphocytes ; cytology ; immunology ; CD8-Positive T-Lymphocytes ; cytology ; immunology ; Cell Differentiation ; Humans ; Receptors, Antigen, T-Cell ; immunology ; Signal Transduction ; T-Lymphocytes ; immunology ; Thymus Gland ; cytology

OBJECTIVETo detect the changes of naive T cell level of thymic recent output at different stages of treatment in patients with diffuse large B-cell lymphoma (DLBCL), thereby to evaluate the relationship of thymic recent output function with prognosis and the impact of chemotherapy on the potential of immunological recovery.

METHODSThe levels of T-cell receptor rearrangement excision circles (TREC) in DNA of peripheral blood mononuclear cells (PBMNC) from 30 DLBCL patients were monitored before, during, until 3 months and 6 months after chemotherapy by real-time PCR (TaqMan), and TREC-level was detected according to the number of CD3 positive(CD3(+)) cells. Twelve normal individuals who matched in age were served as controls.

RESULTSThere was a dramatic reduction of TREC values in all DLBCL patients among which TREC values in germinal center B-cell-like-DLBCL (GCB-DLBCL) were higher than those in non-GCB-DLBCL, as compared with TREC values of normal individual in peripheral blood. The mean values of TREC were 0.91 ± 0.15/1000 PBMNCs and (1.22 ± 0.69)/1000 CD3(+) cells in GCB-DLBCL, (0.43 ± 0.29)/1000 PBMNCs and (0.64 ± 0.44)/1000 CD3(+) cells in non-GCB-DLBCL before chemotherapy. TREC values were significantly associated with lower international prognostic index (IPI) grade (r = -0.441, P = 0.015). TREC-level in DLBCL patients was further decreased after chemotherapy, and reached to the lowest level after the 6th cycle of chemotherapy, and during the corresponding period, the mean values of TREC were (0.63 ± 0.34)/1000 PBMNCs and (0.89 ± 0.65)/1000 CD3(+)cells in GCB-DLBCL, (0.19 ± 0.11)/1000 PBMNCs and (0.27 ± 0.25)/1000 CD3(+) cells in non-GCB-DLBCL. TREC-level began to rise obviously 3 months after the last cycle of chemotherapy in most of the DLBCL patients, and came close to normal level in five cases of patients 6 months after the last cycle of chemotherapy.

CONCLUSIONSThymic recent output function was impaired severely in DLBCL patients. There was an important relationship between thymic recent output function before chemotherapy and prognosis, and chemotherapy had influenced the potential of immunological recovery.

Adult ; Aged ; Case-Control Studies ; Female ; Gene Rearrangement, T-Lymphocyte ; Germinal Center ; immunology ; Humans ; Lymphoma, Large B-Cell, Diffuse ; drug therapy ; immunology ; pathology ; Male ; Middle Aged ; Receptors, Antigen, T-Cell ; immunology ; Thymus Gland ; immunology ; Young Adult

Thymic hyperplasia is frequently observed in Graves' disease. However, detectable massive enlargement of the thymus is rare, and the mechanism of its formation has remained elusive. This case showed dynamic changes in thymic hyperplasia on serial computed tomography images consistent with changes in serum thyrotropin receptor (TSH-R) antibodies and thyroid hormone levels. Furthermore, the patient's thymic tissues underwent immunohistochemical staining for TSH-R, which demonstrated the presence of thymic TSH-R. The correlation between serum TSH-R antibody levels and thymic hyperplasia sizes and the presence of TSH-R in her thymus suggest that TSH-R antibodies could have a pathogenic role in thymic hyperplasia.
Adult ; Female ; Graves Disease/*complications/surgery/therapy ; Humans ; Male ; Receptors, Thyrotropin/blood ; Thymus Gland/diagnostic imaging ; Thymus Hyperplasia/*diagnostic imaging/etiology/immunology ; Thyroid Hormones ; Thyroidectomy ; Thyrotropin/blood ; Tomography, X-Ray Computed ; Young Adult