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Abdomen
Published in Bobby Krishnachetty, Abdul Syed, Harriet Scott, Applied Anatomy for the FRCA, 2020
Bobby Krishnachetty, Abdul Syed, Harriet Scott
In the fetus, the spleen is a site for myelopoiesis (the production of all types of blood cells). After birth, only lymphopoiesis is maintained but abnormal haematopoiesis can be reactivated in myeloproliferative disorders.
Dopamine in the Immune and Hematopoietic Systems
Published in Nira Ben-Jonathan, Dopamine, 2020
T cells are created by lymphopoiesis from a common lymphoid progenitor in the bone marrow. The newly generated cells migrate to the thymus where they undergo extensive maturation and screening. Through a combination of positive and negative selection processes, the cells are differentiated, yielding a repertoire of mature T cells that tolerate self-antigens and are capable of mounting strong responses to foreign antigens. Within the thymus, T cells undergo a V(D)J recombination, a unique mechanism of genetic recombination that occurs only in developing lymphocytes during maturation. It involves somatic recombination that results in a highly diverse assortment of the TCRs. Cell selection in the thymus is accompanied by an extensive cell death by apoptosis and phagocytosis, with only a very small percent of the cells surviving the selection process, and these are exported to extra-thymic sites.
Soluble Mediators of Cellular Cooperation: The Cytokines
Published in Constantin A. Bona, Francisco A. Bonilla, Textbook of Immunology, 2019
Constantin A. Bona, Francisco A. Bonilla
Almost all of the cytokines described above have at least been suggested by in vitro data to play a role in some aspect of hemopoiesis or lymphopoiesis. However, the type I cytokine receptor family, or the hemopoietic growth factor receptor family, is comprised of IL-2R (β and yc), IL-3R, −5R, −6R and GM-CSFR (both a and β chains), and IL-4R, −7R, EPOR, G-CSFR, LIFR, and ciliary neurotrophic factor (see below). This family is defined by two structural elements: at the amino terminus they have a sequence containing conserved cysteines and tryptophan in certain positions; at the carboxyl terminus they have a Trp-Ser-X-Ser-Trp. This family also includes receptors for growth hormone and prolactin which are structurally similar except that they lack the carboxyl terminal motif. These receptors act via a tyrosine kinase pathway but do not have intrinsic tyrosine kinase activity. Presumably, before or after ligand binding, they associate with other molecules which then further transduce a signal or are themselves tyrosine kinases.
Tertiary Lymphoid Structures, Immune Response, and Prognostic Relevance in Non-Small Cell Lung Cancer
Published in Cancer Investigation, 2023
Alexandra Giatromanolaki, Paschalis Chatzipantelis, Constantinos A. Contrafouris, Michael I. Koukourakis
The immune system is composed of many different tissues. The primary (or central) lymphoid organs, destined to generate lymphocytes from immature progenitor cells, are the thymus that is involved in T-cell lymphopoiesis, and the bone marrow that hosts both B-cell and T-cell precursors. Spleen and lymph nodes are secondary (peripheral) lymphoid organs, where B and T-cells are activated after being exposed to antigens, giving birth to mature immune cells that enter the bloodstream to reach the target tissues. During pathological processes, e.g., chronic inflammation or autoimmune conditions, the ‘tertiary lymphoid structures’ (TLS) appear. These are abnormal ‘lymph node-like’ structures that emerge within the affected organs/tissues and are characterized by active germinal centers surrounded by follicular dendritic cells (5). B-cell follicles, T-cell zones are often evident within TLS. Specialized vessels known as high endothelial venules (HEVs) are also present, but TLS do not have afferent lymphatic vessels (6). Within them, both B and T-cell responses can be developed, just like in lymph nodes.
Gut microbiota mediates the inhibition of lymphopoiesis in dietary-restricted mice by suppressing glycolysis
Published in Gut Microbes, 2022
Si Tao, Yiting Wang, Chenghui Yu, Rongrong Qiu, Yanjun Jiang, Jie Jia, Zhendong Tao, Liu Zhang, Bing Zou, Duozhuang Tang
For a long time DR has been promising hope to reduce the burden of aging societies as it promotes healthy aging. However, we and others have uncovered significant inhibitory effects caused by DR on the immune system that could reduce the overall benefits one could get from therapeutic DR. It is therefore important to explore the underlying mechanisms that could mediate the inhibition of lymphopoiesis by DR. The current study provides the first experimental evidence that DR restructures the gut microbiota, which in turn mediates a down-regulation of glycolysis in lymphoid lineages with subsequent inhibition of B and T lymphopoiesis. In addition, we further reveal that DR led to an increase of butyrate-producing bacteria in the gut, with supplemental butyrate-feeding in AL mice able to mimic the restructuring of the gut microbiota and diminishment in lymphopoiesis observed in the DR condition. The current study provides an important clue that could be further explored to minimize the negative effects of DR on lymphopoiesis. A limitation of this study was that only female mice were used in all experiments, which should introduce certain consideration of the generalizability of the results due to the potential variability between different genders.
Therapy-related acute lymphoblastic leukemia following treatment for multiple myeloma – diagnostic and therapeutic dilemma
Published in Acta Oncologica, 2022
Alicja Sadowska-Klasa, Mary Abba, Justyna Gajkowska-Kulik, Jan Maciej Zaucha
Secondary acute leukemia refers to patients with either therapy-related or disease progressing from an antecedent hematologic disorder typically a myelodysplastic syndrome or a myeloproliferative neoplasm. Neither MM is considered a typical neoplasm that leads to secondary hematopoietic neoplasms nor ALL is a typical secondary hematopoietic malignancy. Lymphoblasts and plasmocytes are cells both originating from lymphopoiesis; however, their proliferating potential is very different. Plasma cells represent the final differentiation stage, nevertheless, there are hypotheses that somatic mutations occurring in younger precursors affect further stages of lymphopoiesis, and the final oncogenic events take place in secondary lymphoid organs [19,20]. The hereditary component of MM susceptibility was reported many years ago; however, increased risk for other B-cell originating neoplasms was also noticed in MM-risk families [1,8]. Interestingly tr-ALL, which accounts for up to 9% of all ALL, occurs mainly in women after chemotherapy for breast cancer [21]. Regardless, the second most common cause of tr-ALL is MM [22].