Thymus Degeneration and Regeneration

The immune system’s ability to resist the invasion of foreign pathogens and the tolerance to self-antigens are primarily centered on the efficient functions of the various subsets of T lymphocytes. As the primary organ of thymopoiesis, the thymus performs a crucial role in generating a self-tolerant but diverse repertoire of T cell receptors and peripheral T cell pool, with the capacity to recognize a wide variety of antigens and for the surveillance of malignancies. However, cells in the thymus are fragile and sensitive to changes in the external environment and acute insults such as infections, chemo- and radiation-therapy, resulting in thymic injury and degeneration. Though the thymus has the capacity to self-regenerate, it is often insufficient to reconstitute an intact thymic function. Thymic dysfunction leads to an increased risk of opportunistic infections, tumor relapse, autoimmunity, and adverse clinical outcome. Thus, exploiting the mechanism of thymic regeneration would provide new therapeutic options for these settings. This review summarizes the thymus’s development, factors causing thymic injury, and the strategies for improving thymus regeneration.

The Preconditioning of Busulfan Promotes Efficiency of Human CD133+ Cells Engraftment in NOD Shi-SCID IL2Rγcnull (NOG) Mice via Intra-Bone Marrow Injection

Human CD133+ stem cells were injected into the bone marrow cavity of NOG (NOD Shi-SCID IL2Rγcnull) mice with or without preconditioning of busulfan in order to assess the efficiency of human CD133+ cells engraftment. Peripheral blood from CD133+-engrafted NOG mice was analyzed by flow cytometry. The results showed that human CD19+ B lymphocytes could be detected at 4 weeks post-transplantation, and human CD4+, CD8+ subsets of T lymphocytes, CD19– CD14– HLA-DR+ DCs and CD19– CD14+ monocytes could be detected at 16 weeks post-transplantation. The survival rate of mice in busulfan-untreated group (100%) was slightly higher than that in the busulfan-pretreated group (83%) ( P > 0.05). However, the differentiation efficiency of CD133+ stem cells in busulfan-pretreated group was significantly higher than that in the untreated group ( P < 0.05). This data imply that CD133+ cells could be a good resource for a humanized mouse model, and the preconditioning of busulfan could be more conducive to accelerating the differentiation of human CD133+ cells in NOG mice by intra-bone marrow injection.

The antiviral effects of acteoside and the underlying IFN-γ-inducing action

Acteoside, a natural phenylpropanoid glycoside from Kuding Tea, enhanced IFN-γ production in mouse lymphocytes in a dose-dependent manner, particularly in the CD4+ and CD8+ subsets of T lymphocytes.

Importance of T Lymphocytes in Brain Injury, Immunodeficiency, and Recovery after Cerebral Ischemia

Following an ischemic stroke, T lymphocytes become activated, infiltrate the brain, and appear to release cytokines and reactive oxygen species to contribute to early inflammation and brain injury. However, some subsets of T lymphocytes may be beneficial even in the early stages after a stroke, and recent evidence suggests that T lymphocytes can also contribute to the repair and regeneration of the brain at later stages. In the hours to days after stroke, T-lymphocyte numbers are then reduced in the blood and in secondary lymphoid organs as part of a ‘stroke-induced immunodeficiency syndrome,’ which is mediated by hyperactivity of the sympathetic nervous system and the hypothalamic—pituitary—adrenal axis, resulting in increased risk of infectious complications. Whether or not poststroke T-lymphocyte activation occurs via an antigen-independent process, as opposed to a classical antigen-dependent process, is still controversial. Although considerable recent progress has been made, a better understanding of the roles of the different T-lymphocyte subpopulations and their temporal profile of damage versus repair will help to clarify whether T-lymphocyte targeting may be a viable poststroke therapy for clinical use.

The influence of high selenium intake of ewes on leukocytes in newborn lambs

The aim of this work was to determine the impact of high selenium intake on pregnant ewes considering the number of leukocytes and the representation of T cell subsets in the blood of newborn lambs. An experiment was conducted on nineteen sucking newborn lambs of the Sumava sheep breed. The ewes were divided into three groups of five animals: control C (without Se supplementation), experimental E1 (sodium selenite supplementation, Se content 160 μg.kg-1 DM) and E2 (Chlorella as a carrier for selenium, Se content 160 μg.kg-1 DM). After birth blood samples were taken from lambs on days 1, 3, 10, 30 and 60. The WBC count and proportion of lymphocytes in blood smear were detected by microscopic analysis, and the CD4+ and CD8+ T cell subsets in blood were detected by flow cytometry. The differences determined were not statistically significant due to high variabilities within the groups. In lambs whose mothers were supplemented with selenium bound to the alga of the genus Chlorella a statistically significant increase in the proportion of both subsets of T lymphocytes was proved. The results document a tendency to a lower level of the selected parameters of immunity in lambs without Se supplementation.