Leukaemia

Leukaemia

1. Spleen

   • Functions
     • Immune response against blood-borne antigens
     • Remove damaged cells from circulation
   • Red pulp
     • Parenchyma with macrophages (which destroy damaged RBC) and RBC which have left the capillaries and haven't crossed into the sinuses
     • interconnected venous sinuses which are lined by elongated spindle endothelial cells (stave cells) with slits
   • White pulp
     • T-cells and B-cells.
       • T-cell area forms eccentric cylindrical sheaths around central arteriole
       • B-cells forms follicles which have germinal centers in young people
         • On follicle periphery= mantle zone of small lymphocytes
         • Marginal zone: Less densely packed medium-sized lymphocytes with framework of reticulin fibres
         • Perilymphoid red pulp: Around marginal zone with lymphocytes

2. Lymph Nodes

   • Functions
     • Non-specific filtration of particulate matter and micro-organisms
     • Interaction of circulating lymphocytes with antigen-containing lymph
     • Aggregation (T), Activation and proliferation of T and B lymphocytes
   • Cell types
     • Lymphoid cells
     • Immune accessory cells (macrophages, FDC)
     • Stromal cells (endothelial cells and fibroblasts)
   • Histology
     • Outer hypercellular cortex surrounded by collagenous capsule. C9ortex has lymphoid follicles (B- lymphocytes) and paracortex has no follicles but T-lymph9oids
     • Inner medulla with cords which project into medulla between medullary sinuses
     • Parenchyma= reticulin fibres
     • *Thymus: No follicles in cortex. *Tonsils have one border of strat squam epi. Lymph nodes have follicles and subcapsular space. Spleen has follicle-looking areas which is red pulp surrounding a blood vessel

3. Bone Marrow

   • Red Marrow- White marrow is active and crammed with precursors of cells. Yellow marrow becomes less active with age and dominated by fat cells
   • Framework of reticulin and specialized fibroblasts
   • Interconnected sinusoids which drain to central sinus. Cont endothelium but discont BM. Endothelium active in endocytosis

4. Blood morphology

   • cells
     • Erythrocytes: Transport of oxygen and carbon dioxide. Erythron
     • Leukocytes: Immune defense. Outside the vessels
       • Granulocytes: polymorpho-nuclear leucocytes. Prominent cytoplasm, secretory granules and single multilobed nucleus
         • Neutrophils: Acute inflammation*&*&*&*&*&*&*&
         • Basophil: Allergic reaction
         • Eosinophils: Parasites
       • Lymphocytes: T cells for cell-mediate immunity ans B-cells for humoral immunity. NK cells manly tumors and virally infected
     • Platelets: Control of bleeding (haemostasis) and coagulation cascade
   • Plasma
     • Solution of inorganic salts
     • Proteins
       • Albumin: binds to insoluble molecules such as fatty acids
       • Globulins: Antibodies and proteins which bind lipids and heavy metal ions
       • Fibrinogen: soluble, polymerises to for insoluble fibrin during clotting