Leucocytes and plasma proteins Flashcards
Learning outcomes
• list the different types of leucocytes
• list the defining characteristics of the different types of leucocytes
• list the components of plasma and their functions and explain the
difference between plasma and serum
• list the types of proteins in plasma
• describe the function of plasma proteins
White blood cells (leucocytes)
<1% Total Blood Volume
Important clinical information can be derived
from
-White cell count (WBC) (total number of
leucocytes) and
-Differential white cell count (relative amounts
of different kinds of leucocytes)
White cell count- Normal range: 4 - 11 x 109 L-1
Increases during infection or inflammation
What are the functions of white blood cells?
- Immune response
- Inflammatory response
- Disposal of damaged and ageing cells
What are the 2 groupings of white cell classification?
Polymorphonuclear granulocytes • irregular, multi-lobed nuclei • possess cytoplasmic granules • These are: basophils, eosinophils, neutrophils
Mononuclear agranulocytes
• large, regular nuclei
• lack cytoplasmic granules
• These are: lymphocytes, monocytes
Remember- never let monkeys eat bananas
Neutrophils
- Multi-lobed nucleus
- Inconspicuous cytoplasmic granules
- Specialists in destroying bacteria
- Short life span
- Migrate to areas of infection (chemotaxis)
- Phagocytic
What are the events leading to phagocytosis?
- activation of resting phagocytes by inflammatory mediators
- movement of phagocytes towards chemical attractants – chemotaxis
- margination, rolling and adhesion- leucocytes assume marginal positions in the blood vessels. They stick to the walls of the venules and roll along them until they become firmly attached to the vessel wall (adhesion).
- diapedesis- the passage of blood cells through the intact walls of the capillaries, typically accompanying inflammation.
- recognition-attachment: attachment of phagocyte to pathogen: opsonins- mark molecule for phagocytosis
- Ingestion
- Pathogen killing and degradation- 6+7 refer to lecture 1
Neutrophils are activated by inflammatory mediators- chemicals released by damaged tissue that attract phagocytes/ pathogens, macrophages can also release these
Eosinophils
• Bi-lobed nucleus
• Red cytoplasmic granules
• Migrate to areas of infection (chemotaxis)
• Less active as phagocytes when compared to neutrophils
• Degranulation releases toxic substances aiding defense against larger
parasites
• Increased in allergic disease e.g. asthma, hayfever
• Prolonged elevations lead to tissue damage
Basophils
• Bi-lobed nucleus
• Large purple cytoplasmic granules
• Less active as phagocytes when compared to neutrophils & eosinophils
• Release chemicals at site of infection
- histamine & other mediators of inflammation
- heparin, an anticoagulant
• Involved in allergic responses
• Involved in parasitic responses
• Attract other WBCs
• Migrate to areas of infection (chemotaxis)
• Similar to tissue mast cells
Lymphocytes
• Spherical nucleus
• Pale blue cytoplasm
• 20-40% WBCs
• BUT, small percent of total lymphocytes in body
• Others are outside blood vessels within the body
• Non-phagocytic
• Mount immune response by direct cell attack or via antibodies
3 main types
• T Cells
• B Cells
• Natural Killers (NK)
Type 1. T-Cells
- coordinate immune response
- attack foreign cells directly
- increase/decrease other lymphocytes
- cytotoxic T cells- destroy virus infected and tumour cells, and are implicated in transplant rejection
- Helper T cells- assist other WBCs in immunologic processes, including B cell maturation into plasma and memory B cells, as well as activation of cytotoxic T cells and macrophages
- Regulatory T cells, crucial for maintenance of immunological tolerance
- Memory T cells- subset of antigen specific T cells that persist long term after infection is resolved
Type 2. B-Cells
- Provide humeral immunity (A.B Mediated)
• Attachment of antigen to receptor on surface of
B cell leads to activation
• Become plasma cells - secrete antibodies (γ-globulins)
• Become memory B cells (requires T-helper cell collaboration)
Type 3. Natural Killer (NK) Cells
- Kill infected/cancerous cells
- Cytoplasmic granule contents released
- Perforate cell membrane (perforins)
- Cause cells to initiate apoptosis
If it contacts a ligand on a tumour cell (not expressed in healthy cells), communication pathway occurs inside cell and lysis occurs.
Monocytes
• U- or kidney-shaped nucleus • Blue cytoplasm • Phagocytic • Attract other WBCs and fibroblasts • After 72h enter tissues & become macrophages • Tissue-specific macrophages - Alveolar and peritoneal macrophages - Kuppfer cells - Osteoclasts - Microglial cell in brain - Histiocytes (pyrogens lead to fever)
What are the main types of plasma protein?
Plasma proteins are produced by the liver
Albumin (around 60% total PP)
- Fats, AAs, Enzymes
- Drugs, e.g warfarin
- Non- specific
- Exert plasma oncotic pressure
Globulin (around 35% total PP)
- Ions
- Hormones
- Vitamins- different classes carry diff. substances, e.g iron binding globulin (transferrin), copper binding globulin(ceruloplasmin); thyroxine binding globulin, steroid binding globulin (transcortin)
- Gamma globulins act as antibodies (plasma cells)
Fibrinogen (around 4% total PP)
- Functions in blood clotting
Too large to diffuse through most capillaries: will not mix between plasma and interstitial fluid
