Blood and Immune Flashcards
Major Components of Blood
- Red Blood Cells (40%)
- Buffy Coat, containing white cells (10%)
- Plasma, containing soluble proteins, lipids, platelets (50%)
Plasma
Liquid fraction of uncoagulated blood
- Serum remains after coagulation and is normally straw yellow
- Fibrinogen is absent
Serum Separation
Serum separates in an electric field into:
- Albumin (50%)
- Alpha 1
- Alpha 2
- Beta
- Gamma
Albumin
- 50%
- Functions to maintain colloidal osmotic pressure
- Binds and transports small molecules and proteins
Fibrinogen
- 17%
- Involved in clotting in the coagulation cascade
Immunoglobulin
- 10%
- Found in gamma fraction and are responsible for humeral immunity
- Produced by plasma cells
- Elevated in diseases such as multiple myeloma
Complement (C’)
- Group of zymogens (inactive substance which is converted into an enzyme when activated by another enzyme)
- Essential for phagocytosis
- Stable as zymogens but break down quickly when cleaved
Coagulation
- Set of 13 protein that initiate cleavage of Fibrinogen to Fibrin
- Thrombin is central enzyme
Myeloid Cells
Provide innate immunity
- Neutrophils
- Basophils
- Monocytes (macrophages)
- Eosinophils
Lymphoid
- Provide adaptive immunity
Produces B-lymphocytes (antibodies) and T-Lymphocytes (cellular)
Haematopoiesis
- All blood cells begin as Hematopoietic stem cell (HSC) food in bone marrow - characterised by CD34 marker antigen
CD34+ HSC
Gives risk to myeloid or lymphoid progenitors
Myeloid Progenitor
Gives rise to:
- Erythrocytes
- Mast Cells
- Megakaryocytes (To Throbocytes)
- Myeloblasts (give rise to myeloid cells)
Lymphoid Progenitor
Gives rise to:
- Natural Killer Cells (Large granular lymphocytes)
- Small Lymphocytes (give rise to lymphoid cells)
Erythropoietin (EPO)
- Drives production of RBC
- Mainly in Kidneys in adulthood (liver in perinatal)
Granulocyte Macrophage Colony-Stimulating Factor (GM-CSF)
- Stimulates production of myeloid cells
- Produced by macrophages, T-Cells, endothelial cells, fibroblasts
- Administered to repopulate WBC in cancer patients
Granulocyte Colony-Stimulating Factor (G-CSF)
- Stimulates production of granulocytes
- Acts to mature neutrophils
- Produced by multiple cells
- Administered to repopulate WBC in cancer patients
Complement Cascade
Set of 9 plasma proteins that lead to opsonisation and phagocytosis of foreign organisms
- Proteolytic activation cascade
Classical/Antibody Mediated Complement Cascade
- Antibody (IgM, IgG) binds to an antigen on the microbe thus recruiting C1 to bind to the antibody
- Activation of C2 and C4 molecules which are cleaved (forming C4a, C2a) forming a convertase
- Convertase is covalently bound to the surface of the microbe and recruits C3 which is cleaved to C3b
- More C3 is generated and the surface of the microbe is covered with C3 Convertase forming opsonins
Lectin Complement Cascade
Lectins are carbohydrate binding proteins that bind unusual carbohydrates to the microbe and this activates the convertase pathway
Alternative Complement Cascade
Complement C3 is activated and cleaved just by being close to the surface of the microbe, activating another type of C3 Convertase to form opsonins
End Stage Complement
Convertase activates C5 to cleave and for C5b to form a lytic pore with C6, 7, 8, and 9.
- Pore inserts into a bacterial membrane causing its lysis
- Membrane Attack Complex (MAC)
Anaphylatoxins
Small polypeptides C2a, C4a, C5a which are powerful chemoattractants that recruit and activate phagocytes to engulf the bacteria
- Neutrophils and Macrophages rapidly engulf opsonised bacteria but ignore ones without
Coagulation Cascade
- Proteolytic activation cascade
- Calcium ion essential for clotting
Intrinsic Coagulation Cascade
- Caused by blood contact with surfaces other than the body
- Uses Factor XII, XI, IX, VIII along with the common factor X to form Factor Xa
Extrinsic Coagulation Cascade
- Caused by tissue damage
- Uses Tissue Factor, V, VII along with common factor X to form Factor Xa