AKA Polymorphs, PMNs, polymorphonuclear leucocyte
- 90% of Granulocyte and 75% of normal leucocytes
- Post-mitotic with dense nucleus with 2-5 lobes
- granules in cytoplasm with lysozymes for immediate action
Generated in the marrow from the common myeloid stem cell and myloblast that can divide into both neutrophil and monocyte.
Granulocyte kinetics? Regulation of granulopoiesis?
7-10 day maturation forming segmented nucleus and granules
When released they circulate for 6-10 hours before entering tissues to perform phagocytic functions.
Haematopoietic growth factors - eg. G-CSF is in clinical use in NZ (filgrastim) and increases commitment and maturation as well as release of segmented and band neutrophils into the blood.
- attracted to areas by a number of complement/inflammatory/bacterial products
- receptors for complement forming phagosome
Killing of Bacteria
- (oxidative and non oxidative)
Clinical relevance of neutrophils?
- feature of infection and inflammation (CBC done to check if its appendicitis)
- may be associated with a left shift (more immature forms in the blood)
Patients with a low neutrophil count
- Termed NEUTROPENIA
- At risk of infection (febrile neutropenia)
Neutrophil function defects (rare)
- unable to respond to infections properly
What are monocytes?
Large cells (bigger than neutrophils)
Central oval or indentef nuclei
Less than 10% of total WBC count
Mature in the bone marrow with a common precursor as neutrophil from monoblast to promonocyte to monocyte.
Monocytes circulate for 1-3 days before entering the tissue and transforming into macrophages. These macrphages are known as specific names based on location (Kupffer cells in liver, Langerhans cells in skin, Microglial cells in brain etc)
- Chronic infection, intracellular parasites eg. TB
- Opsonisation - receptors Fc and C3
- Phagocytosis and ingestion
- Killing of ingested bacteria by fusion with monocytic lysosomal ganules
Synthetic Function (they make components of:)
- cytokines eg. TNF, IL1, GF
Clinical relevance of monocytosis?
Reactive - chronic infection like TB or osteomyelitis
Malignant - acute myeloid leukaemia - (monoblast subtype), chronic myelomocytic leukaemia (CMML)
Similar to neutrophils but:
- Bilobed nucleus
- red stained granules
- In very small amounts compared to neutrophils and monocytes
- developmental stages similar to neutrophils
- Is an allergic or hypersensitivity reaction (eg. hayfever, asthma, drug reactions)
- A parasitic infestation (often gut) and can be totally asymptomatic
They are normally involved in dampening down these reactions. A chemotactic factor is released for eosinophils along with histamines etc.
Infrequently found cells in the blood that:
- stain deep blue granules over the nucleus (dont see the nucleus)
- have IgE binding sites
- are related to mast cells ith granules containing histamine, SRS-A and ECF-A and
- like eosinophils are involved in type 1 hypersensitive reaction
Small mature cells just slightly bigger than RBC with a large nucleus to cytoplasm with no granules.
65-80% T cells and 5-15% B cells with a small number of NK cells that are slightly larger and may have cytoplasmic granules
Bone marrow derived cells with a common lymphoid stem cell and lymohoblasts as precursors.
Primary lymphoid organs?
Lymphocyte bone marrow derived but maturation in these primary lymphoid organs
B cells = Bone Marrow
T cells = Thymus
This maturation is where they learn to recognise self from non-self.
Secondary Lymphoid organs?
Migration from the PLO to the SLO:
- Lymph nodes
- Lymphoid tissue throughout the body
- Bone marrow
Here they: Generate an adaptive immune response
Clinical relevance of lymph node enlargement? Lymphocytosis?
Reactive (eg. viral infection, local bacterial infection)
Malignant (eg. Of lymphoid tissue - Lymphoma - or metastatic spread)
- Reactive - viral infections
- Malignant - eg. chronic leucocytic leukaemia
HIV infection: CD4 pos T cells
- profound T cell defecit
- opportunistic infections
Others: congenital immune defects, steroid therapy, severe bone marrow failure.