White Blood Cells WBCs White Blood cells are also known as Leucocytes as they are colorless due to lack of Haemoglobin. There are about 6000-8000mm of WBC for 1ml of blood.

WBC’s Five Types Classified according to the presence or absence of granules and the staining characteristics of their cytoplasm. Leucocytes appear brightly colored in stained preparations, they have a nuclei and are generally larger in size than RBC’s.

Leukocytes 1-Phagocytes -Granulocytes ( Neutrophils, Eosinophils, Basophils) -Monocytes 2-Immunocytes Lymphocytes

Formation of WBC’s Leucocytes are formed in the red marrow of many bones. They can also be formed in lymphatic tissue. They live for about 13-20 days.

Granulopoiesis -Common precursor -Bone marrow -Common precursor -Normally, BM storage 10-15 times the number of granulocytes than peripheral blood -Stay for 6-10 hrs then move to their tissues to perform their phagocytic functions.

Granylopoiesis Many growth factors are involved in: Maturation of these cells Proliferation and Differentiation Function Interleukin-1 (IL-1),IL-3,IL-6 + GM-CSF (granulocyte-macrophage colony-stimulating factor) eosinophil (IL-5)

Growth factors Infection Causes an Induction of GF productions Increases No. of granulocytes & Monocytes

Granulocytes—have large granules in their cytoplasm Type of WBC’s Granulocytes—have large granules in their cytoplasm Neutrophils Eosinophils Basophils

Granuloctyes Neutrophils Stain light purple with neutral dyes Granules are small and numerous—course appearance Several lobes in nucleus 65% of WBC count Highly mobile/very active Diapedesis—Can leave blood vessels and enter tissue space Phagocytosis (eater), contain several lysosomes (janitor)

Agranulocytes Monocytes Largest of WBCs Dark kidney bean shaped nuclei Highly phagocytic

Granulocytes: Neutrophils/Eosinophils/Basophils Classified according to cell morphology and cytoplasmic staining Neutrophils: stains with BOTH acid and basic dyes. called ‘PMN’ for lobed nucleus; 50% of circ leukocytes Eosinophils: stain with ACID dye (Eosin-red); bilobed nucleus 1-3% of leuko’s. Basophils: stain with BASIC dye (Methylene blue); <1% of leuko’s

Neutrophils Circulate in peripheral blood 7-10 hr before migrating into tissue; live only a few days “front line of innate defense” Attracted by chemotactic factors Active phagocytes; digestive enzyme held in 1° and 2° granules Use both O2-dep and O2- indep digestive mech’s Produce high levels of defensins

Neutrophil

Granulocytes Eosinophils or Acidophils: Large, numerous granules Nuclei with two lobes 2-5% of WBC count Found in lining of respiratory and digestive tracts Important functions involve protections against infections caused by parasitic worms and involvement in allergic reactions Secrete anti-inflammatory substances in allergic reactions

Eosinophils and Basophils Eosino’s Like Neutrophils, function in phagocytosis function vs. parasitic infections contents of released granules damages parasitic particals.

Basophils Least numerous--.5-1% Diapedesis—Can leave blood vessels and enter tissue space Contain histamine,serotonin,heparin— inflammatory chemical

Basophils

Types of WBC’s Agranulocytes—do not have granules in their cytoplasm Lymphocytes Monocytes

Monocytes Large Pbl Large central oval nucleus with clumped chromatin

Monocytes Short time in BM 20-40hrs in circulation Move to tissues, mature(Macrophages) & DCs ,carry out their main functions.

Monocytes & Neutrohpils Functions 1-Chemotaxis ( Cell mobilization and migration) Phagocyte is attracted to Microbes or Inflammation site By chemotactic Substance from damaged tissues By leukocyte adhesion molecules and tissues ligands.

Phagocytosis: Dead/ damaged cells of the host or microbes. Recognition Opsonization Destruction

Killing & Digestion: O2-dependent O2-independent pathways

WBC Numbers Clinics will count the number of WBC’s in a blood sample, this is called differential count. A decrease in the number of white blood cells is leukopenia An increase in the number of white blood cells is leukocytosis.

Disorders of Neutrophil & Monocyte Function 1-Defects of phagocytic cell function 2-Benign disorders

Defects of Phagocytic cell function -Chemotaxis: Lazy Leucocyte Syndrome -Phagocytosis: lack of opsonization Hypogammaglobulinaemia -Killing: x-linked autosomal recessive chronic granulomatous disease

Neutrophil leukocytosis An increase of Neutrophils count greater than 7.5*109

Eosinophilic leucocytosis Eosinophilia An increase of blood Es. Above 0.4*109

Basophil leucocytosis Basophilia An increase of blood Baso. Above 0.1*109(rare). Cause: Myloprolifretive disorder.

Monocytosis A rise in blood monocytes count above 0.8*109

Neutropenia A Decrease of normal neutrophils count below 2.5*109