White Blood Cells Dr Gihan Gawish

Definition: leukocytes are cells of the immune system defending the body against both infectious disease and foreign materials. Formation: Five different and diverse types of leukocytes exist, but they are all produced and derived from a multipotent cell in the bone marrow known as a hematopoietic stem cell. Occurrence: Leukocytes are found throughout the body, including the blood and lymphatic system Dr Gihan Gawish

Hematopoietic stem cell Dr Gihan Gawish

Normal range 9 There are normally between 4×10 and 11×10 white blood cells in a liter of blood, making up approximately 1% of blood in a healthy adult. The number of leukocytes in the blood is often an indicator of disease. 9 Dr Gihan Gawish

White blood cells (LEUKOCYTES) Classification Granulocyte Agranulocyte (lymphoid cells) Neutrophil Eosinophil Basophil Lmphocytes Monocytes The term granulocyte is due to the presence of granules in the cytoplasm of these cells. These granules have a different affinity towards neutral, acid or basic stains and give the cytoplasm different colors. Dr Gihan Gawish

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1.Neutrophil They are also known as polymorphonuclear (multilobed) leukocytes. They have a multilobed nucleus which may appear like multiple nuclei, hence the name polymorphonuclear leukocyte. The cytoplasm may look transparent because of fine granules that are faintly pink in color. Dr Gihan Gawish

Function of Neutrophil Neutrophils defend against bacterial or fungal infection and other very small inflammatory processes that are usually first responders to microbial infection Their activity and death in large numbers forms pus. Neutrophils are very active in phagocytosing bacteria and are present in large amount in the pus of wounds. These cells are not able to renew their lysosomes used in digesting microbes and die after having phagocytosed a few pathogens Dr Gihan Gawish

Neutrophil Lifetime Granules Nucleus Main targets Diameter (μm) Approx. % in adults 6 hours-few days fine, faintly pink multilobed bacteria fungi 10-12 54-62% Dr Gihan Gawish

2.Eosinophil Generally their nucleus is bi-lobed. The cytoplasm is full of granules which assume a characteristic pink-orange color with eosin stain. Function: Eosinophils primarily deal with parasitic infections and an increase in them may indicate such. Eosinophils are also the predominant inflammatory cells in allergic reactions. The most important causes of eosinophilia include allergies such as asthma, hay fever, and hives; and also parasitic infections. Dr Gihan Gawish

Eosinophil Lifetime Granules Nucleus Main targets Diameter (μm) Approx. % in adults 8-12 days full of pink-orange Bi-lobed parasites in allergic 10-12 1-6% Dr Gihan Gawish

3. Basophils The nucleus is bi- or tri-lobed, but it is hard to see because of the number of coarse granules which hide it. They are characterised by their large blue granules. Function: Basophils are chiefly responsible for allergic and antigen response by releasing the chemical histamine causing inflammation. Dr Gihan Gawish

Basophils <1% Granules Nucleus Main targets Diameter (μm) Approx. % in adults large blue Bi-lobed or Tri-lobed in allergic Rx 15-12 <1% Dr Gihan Gawish

4. Lymphocyte Lymphocytes are much more common in the lymphatic system. Lymphocytes are distinguished by having a deeply staining nucleus which may be eccentric in location It has a relatively small amount of cytoplasm. Dr Gihan Gawish

The blood has three types of lymphocytes: 1-B cells: B cells make antibodies that bind to pathogens to enable their destruction. Some B cells will retain the ability to produce an antibody to serve as a 'memory' system.) after an attack with pathogens Dr Gihan Gawish

types of lymphocytes: 2-T cells: CD4+ (helper) T cells co-ordinate the immune response and are important in the defense against intracellular bacteria. In acute HIV infection, these T cells are the main index to identify the individual's immune system activity. CD8+ cytotoxic T cells are able to kill virus-infected and tumor cells. CD8+ cells are also another index to identify human's immune activity. γδ T cells possess an alternative T cell receptor as opposed to CD4+ and CD8+ αβ T cells and share characteristics of helper T cells, cytotoxic T cells and natural killer cells. Dr Gihan Gawish

Lymphocyte Lifetime Granules Main targets Diameter (μm) Approx. % in adults weeks to years deeply staining B cells: pathogens CD4+ extracellular bacteria broken down into peptides CD8+ virus-infected tumor cells. γδ T cells: 7-8 25-33% Dr Gihan Gawish

Monocyte 5. They have the kidney shaped nucleus and are typically agranulated. They also possess abundant cytoplasm. Function: Monocytes share the "vacuum cleaner" (phagocytosis) function of neutrophils Monocytes eventually leave the bloodstream to become tissue macrophages which remove dead cell debris as well as attacking microorganisms. Dr Gihan Gawish

Monocyte Lifetime Nucleus Main targets Diameter (μm) Approx. % in adults hours-days kidney shaped Monocytes migrate from the bloodstream to other tissues and differentiate into tissue resident macrophages or dendritic cells 14-17 2-8% Dr Gihan Gawish

Macrophage Phagocytosis (engulfment and digestion) of cellular debris and pathogens, and stimulation of lymphocytes and other immune cells that respond to the pathogen activated=days immature=months-years Dr Gihan Gawish

Dendritic cells Main function is as an antigen-presenting cell (APC) that activates T lymphocytes. activated=days immature=months-years Dr Gihan Gawish

Leukemia Leukemia is a cancer of the blood or bone marrow It is characterized by an abnormal proliferation (production by multiplication) of blood cells, usually white blood cells Dr Gihan Gawish

Four major kinds of leukemia Chronic Acute Cell type Chronic lymphocytic leukemia (CLL) Acute lymphoblastic leukemia (ALL) Lymphocytic leukemia or lymphoblastic Chronic myelogenous leukemia (CML) Acute myelogenous leukemia (AML) Myelogenous leukemia also myeloid or nonlymphocytic Acute leukemia is characterized by the rapid increase of immature blood cells Chronic leukemia is distinguished by the excessive build up of relatively mature, but still abnormal, blood cells Dr Gihan Gawish