Dr Q Sedick White blood cells
Haemopoeisis • Haemopoeisis starts with a pluripotential stem cell that gives rise to separate cell lineages.
Leucocytes May be divided into 2 groups: 1.Phagocytes:granulocytes & monocytes 2.Immunocytes:lymphocytes & plasma cells Phagocytes & immunocytes serve to protect the body against infection using immunoglobin and complement systems.
Granulocytes • Comprised of neutrophils, eosinophils & basophils
Neutrophil development
Granulopoeisis • Many growth factors are involved in the maturation process • Includes IL-1/IL-3/IL-5/IL-6/IL-11/GM-CSF/G-CSF/M-CSF • GF stimulate proliferation and differentiation and also affect the function of mature cells on which they act
Neutrophils • Characterized by a dense nucleus consisting of 2-5 lobes, pale cytoplasm with an irregular outline containing many fine pink granules
Neutrophil granules • Consists if primary & secondary granules • Primary : myeloperoxidase/acid phosphatase/acid hydrolases • Secondary: collagenase/lactoferrin & lysozyme
Monocytes Large oval/indented nucleus, clumped chromatin & abundant blue cytoplasm
Neutrophil/monocyte functions • Chemotaxis-phagocytes are attracted to bacteria by chemotactic substances released from the damaged tissues/by complement or by leucocyte adhesion molecules • Phagocytosis-neutrophils & monocytes have FC and C3B receptors which aid in opsonization of bacteria
Neutrophil/monocyte function • Secretion of growth factors & chemokines-aid in pro-inflammatory processes • Killing and digestion: via oxygen-dependant and oxygen- independent pathways
Eosinophils • Consists of 2-3 nuclear lobes/ red-staining coarser cytoplasmic granules • Enter inflammatory exudates • Special role in allergic responses/defense against parasites and removal of fibrin formed during inflammation
Basophils • Dark cytoplasmic granules which overly the nucleus • Contain heparin and histamine-released on degranulation • Have IGE attachment sites • In tissues-mast cells
Defects of leucocytes NEUTROPHIL LEUCOCYTOSIS: >7,5 X 10^9/L • Bacterial infections, e.g. : periodontitis • Inflammation and tissue necrosis, • Metabolic disorders • Neoplasm's • Acute haemorrhage/ haemolysis • Drugs e.g. :lithium
Leucocytosis… • Haematological malignancies: CML/myeloproliferative disorders/polycythaemia vera/myelofibrosis/AML • Treatment with myeloid growth factors • Asplenia • Rare inherited disorders, e.g.: Down syndrome
The leukemoid reaction • Reactive and excessive leucocytosis characterised by the presence of immature cells in the peripheral blood • Seen in severe chronic infections/severe haemolysis & metastatic cancer
Severe chronic infections
Malignancy
Eosinophilia >0,4 x 10^9/l Causes are as follows: • Allergy / atopy • Parasitic disease • Skin diseases- urticuria • Drug-induced • Asthma & pulmonary syndromes-association with nasal polyps
Urticuria
Eosinophilia • Vasculitidis-polyarteritisnodosa • Malignancies-metastatic and haematological • Chronic eosinophilicleukaemia • Hypereosinophilic syndrome
Allergy/atopy
Basophilia • >0,1 x 10^9/l • Causes include reactive and malignant • Reactive: infections like small pox & chicken pox • Myeloproliferative disorders-Chronic myeloid leukaemia
Monocytosis >0,8 x 10^9/l • Chronic bacterial infections • Protozoan infections • Collagen vascular disease-SLE • Lymphoma • Myelodysplasia
Neutropaenia <2,5 x 10^9/l • Infections of the mouth & throat(bacterial/viral) • Immune-SLE,hypersensitivity,anaphylaxis • Drug-induced • Congenital - Kostmanns syndrome • Bone marrow failure
Lymphocytes • Lymphocytes are the immunologically competent cells that assist the phagocytes in defense of the body against infection • They are involved in processes such as antigen specificity and immunological memory
Lymphocyte development • Consists of T and B cells • B cells: Derives from the stem cell,matures in the bone marrow and circulates in the peripheral blood until antigen recognition On activation B cells secrete immunoglobulin and is known as plasma cells
B cells/plasma cells
T cells T CELLS: • Derive from the thymus and differentiates into mature T cells during its passage to the bone marrow • Involved in immunological processes such as cell mediated cytotoxicity
Lymphocytosis • Acute infections-infectious mononucleosis/rubella/pertussis/mumps/herpes/CMV/HIV • Chronic infections-TB/brucellosis/syphillus • Chronic lymphocytic leukaemias • Acute lymphoblastic leukaemia/NHL
Infectious mononucleosis
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