Agranulocytosis 10.pdf

# Agranulocytose - **Agranulocytter** are strongly reduced with agranulocytose, while agranulocytes dominate the image. - This name is often misunderstood, as many believe that agranulocytes are gone, when it is actually the agranulocytes that are present. - The condition can be fatal, especially i...

# Agranulocytose - **Agranulocytter** are strongly reduced with agranulocytose, while agranulocytes dominate the image. - This name is often misunderstood, as many believe that agranulocytes are gone, when it is actually the agranulocytes that are present. - The condition can be fatal, especially in the context of weakened patients. - **Causes** include various types of poisoning. - **Agranulocytes consist of:** - lymphocytes, which make up 20-25% of all leukocytes. - monocytes, which make up 3-8% of all leukocytes. - Agranulocytes are between one-fourth and one-third of all white blood cells. ## Lymphocytes - Vary in size. - Have a small cytoplasm and a large nucleus. - Two types of lymphocytes exist: - **T-lymphocytes** are an active part of the immune system's cells. - **B-lymphocytes** can be converted into antibody-producing plasma cells. - T-lymphocytes and B-lymphocytes are the same size as granulocytes (about 10 µm). - The large nucleus almost fills the cell and is surrounded by a small rim of light blue cytoplasm. ### Lymphocyte development - **B-cells** are formed in the bone marrow, produce antibodies, and activate the T-lymphocytes. - **T-cells** are formed in the thymus, participate in the cellular immune response, and operate through extracellular contact with other cells. - Some T-cell types (T-lymphocytes) develop into killer cells. - To work, these types of lymphocytes must be close to the cell that needs to be destroyed. They release a locally active substance (perforin) that perforates the cell membrane. ### B-cell development - They are developed in other places like the intestines, bone marrow, and lymph nodes. - They transform into plasma cells and produce free antibodies. - The thymus-produced killer cells are especially feared during transplant rejection. - They swarm around the foreign tissue, and various measures are aimed at suppressing them to protect the transplanted organ (e.g., a transplanted kidney). ## Monocytes - Along with granulocytes, are phagocytic cells. - They are formed in the bone marrow and then circulate in the blood, but stay there for only a short period. - Monocytes can travel outside of the blood vessels and transform into macrophages involved in the body's defense system. ## Monocytes - Description - Large cells (more than 10 µm). - The shape of the nucleus varies. - It is often kidney-shaped or horseshoe-shaped. - The cytoplasm is grayish-blue, dusty, or slate-colored. ## Blood Platelets (Thrombocytes) - Round, biconvex discs. - They are approximately 3 µm in diameter. - There are about 250,000 per mm³ blood. - They play a major role in blood coagulation. ### Blood Platelet Function - When a blood vessel is damaged, platelets gather at the site and form a plug, sealing off minor defects. - Platelets also release factors essential for blood clotting. - During coagulation, the soluble protein fibrinogen is transformed into insoluble fibrin, creating a network of threads. ## Lymph - Cell-free fluid that forms in our tissue, then collects in small vessels called lymph. - Interstitial fluid between cells collects in the lymphatic system, and is transferred back to the bloodstream. - During its passage through the lymph nodes located between the lymphatic vessels, it mixes with lymphocytes. ### Lymph Function - Every cell in the body is surrounded by tissue fluid that is identical to cell-free lymph. - Lymph is formed when plasma (excluding plasma proteins) is "pressed" out of the tissue from the arterial end of the capillaries. - Most of the lymph re-enters the capillary at the venous end, but a surplus remains. - This surplus is removed through the lymphatic system. - The lymph around individual cells is crucial for the exchange of substances between blood and cells. - If the lymph surplus is not drained, the tissue becomes swollen. This process is harmful locally and reduces the amount of fluid in the blood vessels. ## Reticular Connective Tissue - Found in lymph nodes and the red bone marrow. - The site of red and white blood cell formation. - In lymph nodes, it is also referred to as lymphatic or lymphoid tissue. - In red bone marrow, it is referred to as myeloid tissue. - These two forms of reticular connective tissue share common elements: - Reticular cells with reticular fibers. - Free cells.