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 & monocytes2.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 functions1. 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 function3. 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/L1.Bacterial infections, e.g. :

periodontitis2.Inflammation and tissue necrosis, 3.Metabolic disorders4.Neoplasm's5.Acute haemorrhage/ haemolysis6.Drugs e.g. :lithium

Leucocytosis…

7. Haematological malignancies: CML/myeloproliferative disorders/polycythaemia vera/myelofibrosis/AML

8. Treatment with myeloid growth factors

9. Asplenia10.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/lCauses are as follows:1.Allergy / atopy2.Parasitic disease3.Skin diseases- urticuria4.Drug-induced 5.Asthma & pulmonary syndromes-

association with nasal polyps

Urticuria

Eosinophilia

6. Vasculitidis-polyarteritis nodosa7. Malignancies-metastatic and

haematological8. Chronic eosinophilic leukaemia9. 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/l1.Chronic bacterial infections2.Protozoan infections3.Collagen vascular disease-SLE4.Lymphoma5.Myelodysplasia

Neutropaenia

<2,5 x 10^9/l1.Infections of the mouth &

throat(bacterial/viral)2.Immune-

SLE,hypersensitivity,anaphylaxis3.Drug-induced4.Congenital - Kostmanns syndrome5.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