Dr Q Sedick

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 1. Chemotaxis-phagocytes are attracted to bacteria by chemotactic substances released from the damaged tissues/by complement or by leucocyte adhesion molecules 2. Phagocytosis-neutrophils & monocytes have FC and C3B receptors which aid in opsonization of bacteria

Neutrophil/monocyte function 3. Secretion of growth factors & chemokines- aid in pro-inflammatory processes 4. 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 1. Bacterial infections, e.g. : periodontitis 2. Inflammation and tissue necrosis, 3. Metabolic disorders 4. Neoplasm's 5. Acute haemorrhage/ haemolysis 6. Drugs e.g. :lithium

Leucocytosis… 7. Haematological malignancies: CML/myeloproliferative disorders/polycythaemia vera/myelofibrosis/AML 8. Treatment with myeloid growth factors 9. Asplenia 10. 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: 1. Allergy / atopy 2. Parasitic disease 3. Skin diseases- urticuria 4. Drug-induced 5. Asthma & pulmonary syndromes- association with nasal polyps

Urticuria

Eosinophilia 6. Vasculitidis-polyarteritis nodosa 7. Malignancies-metastatic and haematological 8. Chronic eosinophilic leukaemia 9. 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 1. Chronic bacterial infections 2. Protozoan infections 3. Collagen vascular disease-SLE 4. Lymphoma 5. Myelodysplasia

Neutropaenia <2,5 x 10^9/l 1. Infections of the mouth & throat(bacterial/viral) 2. Immune-SLE,hypersensitivity,anaphylaxis 3. Drug-induced 4. Congenital - Kostmanns syndrome 5. 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 1. Acute infections-infectious mononucleosis/rubella/pertussis/mumps/herpes/CMV/ HIV 2. Chronic infections-TB/brucellosis/syphillus 3. Chronic lymphocytic leukaemias 4. Acute lymphoblastic leukaemia/NHL

Infectious mononucleosis