Immunology Lesson 1: Origins and Sites - PDF

Immunology Immunology Lesson 1: ORIGINS AND SITES Haematopoiesis Bone marrow is the site of circulating blood cell production – haematopoiesis Division of haematopoietic stem cells (HSC) one daughter cell remains in the bone marrow to continue renewing the HSC pool o...

Immunology Immunology Lesson 1: ORIGINS AND SITES Haematopoiesis Bone marrow is the site of circulating blood cell production – haematopoiesis Division of haematopoietic stem cells (HSC) one daughter cell remains in the bone marrow to continue renewing the HSC pool other daughter cell will pass through several stages of development (see Figure) resulting in mature blood cells Blood and tissue production in Bone Marrow HSC differentiate into MPPs (multipotent progenitors) CLPs (common lymphoid progenitors) CMPs (common myeloid progenitors)  BONE MARROW DISORDERS Leukemias are malignant diseases of the bone marrow occur during haematopoietic development of: lymphoid lineages in acute or chronic lymphoblastic leukaemia (ALL/CLL) myeloid lineages in acute or chronic myeloid leukaemia (AML/CML Myeloproliferative disorders are characterized by the overproduction of one type of blood cell essential thrombocythaemia (platelets) polycythaemia vera (red blood cells) myelofibrosis (fibroblasts) Myelodysplastic syndromes (MDS) are a spectrum of disorders (overproduction of one or more type of blood cell) Multiple myeloma Aplastic anemia  LYMPH NODE Activation of T and B cells Lymph node location connected to lymphatic and blood vessels Lymph node structure the Cortex (outer layer) contains B-cell areas (follicles) the Paracortex (middle layer) contains T cells and dendritic cells Lymph vessels enter the nodes at the outer edge B and T cells leave the node via ‘efferent’ lymphatic vessels in the central ‘medullary’ region Important in pathogen responses Dendritic cells present pathogenic peptides to T cells. T cell activation and differentiation Some T cells promote B cell activation IMMUNITY IN THE GUT Large intestine (colon) – 1012 microorganism per gram of luminal content Constant threat of potential pathogens Pathogens enter via intestinal mucosa Gut-associated lymphoid tissues Organised lymphoid tissue – Peyer’s patches and mesenteric lymph nodes Mucosal epithelium sites of immune cell activation (and regulation): Mucosal epithelium, lamina propria T cells, plasma cells, mast cells, dendritic cells, macrophages Epithelium has a barrier function Defects in barrier function contribute to the development and perpetuation of inflammation in inflammatory bowel disease (IBD)  IMMUNITY IN THE LUNGS Physical and soluble barriers Nasopharynx and tonsillar regions – clear by inertial force (coughing and sneezing) Mucociliary surface capture and expelling via upper airways Antimicrobial compounds Collectins, surfactant proteins Get recognized by innate immune cells and the complement system Antimicrobial peptide secretions Alveoli the terminal branches of the lungs majority of gaseous exchange occurs here Alveolar macrophages phagocytosis recruitment of other immune cells