SLIDE NO.3b

1. Blood Types
Blood of different types has antigenic and immune properties
Antibodies of one blood in plasma will react with antigens on surface of red cells
of another type cause agglutination and hemolysis of RBCs
Donor and recipient are same then transfusion can occur
30 commonly occuring antigens and 100s of rare antigens found in human blood
cells
ABO and Rh system are the most common types and more likely to cause blood
transfusion reactions and hence well studied

2. ABO system A and B Antigens are agglutinogens and are inherited
A antigen present: A type
B antigen present: B type
A and B both present: AB type
A and B both not present: O type
2genes, one on one of the paired chromosomes determine ABO blood group
O is functionless as agglutinogen
A and B cause strong agglutination
OO, OA, OB, AA, BB, AB
Agglutinin: when type A is not present then it contains anti-A agglutinins to develop in plasma
OO anti A and anti B
OA,AA anti B
OB,BB anti A
AB -
Agglutinins are gamma globulins and produced in bone marrow and lymph glands. IgG and IgM
antiA and antiB can enter thro food and bacteria to initiate development of anti A and B
Agglutinogen: substance acting as an antigen or stimulates production of agglutinin
Agglutinin: is a substance that causes particles to coagulate to form a thickened mass,
Antibodies

3. ABO system
Agglutination reactions occurs if blood type is not matched and transfused
Agglutinins attach to RBCs; IgG (2 binding sites) and IgM (10 binding sites)
Cause clumping (agglutination) which plug circulatory system, physical distortion
Or attack by phagocytic cells, rupture RBCs cause hemolysis
Rh system
Consists of 50 blood group antigens among which C,c,D,d, E,e are most important ones
Commonly used Rh factor, Rh +ve and Rh -ve refers only to D antigen, it is a relevant
cause of hemolytic disease of newborn or erythroblastosis foetalis
C antigen: c is absent
c antigen C is absent
Same for D-d and E-e antigens
D is more prevalent and more antigenic than others
When D antigen is present Rh+ve (85%)
When D antigen is absent Rh-ve (15%)
H antigen is precursor to ABO; Chromosome 19; encodes fucosyl transferase
ABO gene on 9th chromosome

4. Rh system
Anti Rh:
RBCs (Rh+ve) injected into Rh-ve -----> anti Rh develops---> agglutination
2-4 months later
Multiple exposure----> sensitization to Rh factor
Delayed response
Again exposure
Heightened response----> agglutination
Erythroblastosis Foetalis
Agglutination of foetus blood
Hemolysis, release of Hb in blood
Fetus macrophage degrade RBCs
Release bilirubin
Skin yellow (jaundice)
Attack other cells of body
Anaemia
Enlargement of liver and spleen
More RBCs produced
Nucleated blastic red blood cells formed and released in circulatory system
Death…if survive permanent mental damage due to precipitation of bilirubin in neuronal
cells called kernicterus

5. Erythroblastosis Foetalis: prevention
Rh immunoglobulin globulin and anti D antibody is administered to mother
At 28-30 weeks of gestation to prevent sensitization of mother to D antigen
present in fetus
Reduces risk during second pregnancy

6. EFFECTS OF TRANSFUSION REACTIONS:MISMATCHING BLOOD TYPES
HEMOLYSIS
PHAGOCYTOSIS
BILIRUBIN
JAUNDICE
KIDNEY FAILURE: within minutes to few hours
Ag-Ab reaction
Release of toxic substances from hemolysing blood
Renal vasoconstriction
Loss of circulating RBCs; immune reaction
Circulatory shock
Arterial blood pressure falls low
Decr renal blood flow
Decr urine output
Hb precipitation
Blockage of kidney tubules
Acute renal shut down
Death within week to days----unless treated with artificial kidney
Hb (more) + Haptoglobin
Tubular Hb rises

7. TISSUE AND ORGAN TRANSPLANTATION
Tissues have additional complement of antigens
Transplantations result in immune reactions
Organ /tissue from One animal to same animal: AUTOGRAFT
From one twin to another twin: ISOGRAFT
One human to another human or animal to another animal: ALLOGRAFT
(same species) (same species)
Lower animal to human or animal (one sp.) to human (diff sp): XENOGRAFT
Autografts and Isografts same antigens are present hence normal
Xenografts always cause immune reactions causing death in 1day to 5 weeks
Skin
Kidney
Heart
Liver
Glandular tissue
Bone marrow
Lung
Success rate for 5-15yrs for allograft and for liver and heart 1-15 yrs

8. TISSUE AND ORGAN TRANSPLANTATION
Tissue typing
HLA antigens
SIX are present on tissue cell membranes
150 different antigens---trillion combinations
Difficult for 2 persons to have same six HLA antigens except identical twins
Immunity against any one can cause graft rejection
HLA antigens are present on WBCs and tissue cells
Tissue typing is done for lymphocyte membranes from persons blood
Lymphocyte + anti sera +complement----> incubation----> membrane damage check
Trans membrane
Uptake of dye by cell membrane
Best possible match is done
Siblings, parent-child, identical twins (best; never rejected)

9. Hemostasis and Blood Coagulation
Hemostasis is prevention of blood coagulation when rupture occurs
1. Vascular constriction
2. Platelet plug
3. Blood clot due to blood coagulation
4. Growth of fibrous tissue into clot to close hole permanently
A. VASCULAR CONSTRICTION
Myogenic spasm
Factors from tissues and platelets
Nervous reflexes
More vasoconstriction
Blood flow decr
Platelets----> Thromboxane A2
(vasoconstrictor substance)

10. B. PLATELET PLUG Platelets 150,000-300,000 per ul
No nucleus and cannot reproduce
Cytoplasm has active substances
1. Actin myosin molecules
2. Thrombosthenin (cause platelet contraction)
3. ER and golgi bodies to synthesisze enzymes and Ca++
4. Mitochondria (ATP, ADP formation)
5. Prostaglandins (for vascular local tissue reactions)
6. Fibrin stabilizing factor
7. Growth factor: for repair of vascular walls
Responsible for closing several ruptures in minor blood capillaries and endothelial cells
If platelet count is low: hemorrhagic areas under skin

11. B. PLATELET PLUG Mechanism of Platelet Plug
Damaged vascular wall
Collagen fibres + platelets
Swelling of platelets
Irregular shape with pseudopods
Contractile proteins
Release of grannules (active factors)
Become sticky (protein; von Willbrand factor leaks into traumatized tissue)
Secretion of ADP + thromboxane A2
No. of platelets are formed; stick
Platelet plug

12. C. BLOOD COAGULATION: BLOOD CLOTTING
•15-20 sec (major cut) and 1-2 min (minor cut) to form blood clot
•Clotting factors are released
•Opening is filled with clot
•After 20min clot is retracted; closes vessel even more
1. Severed vessel 2. Platelets agglutinate
4. Fibrin clot forms 5. Clot retraction
3. Fibrin appears

13. C. BLOOD COAGULATION: MECHANISM
NORMAL
VESSEL RUPTURE
Cascade of blood clotting factors and formation of PROTHROMBIN ACTIVATOR
Fibrinogen Fibrinogen monomer
Thrombin Activated Fibrin
stabilizing factor
Fibrin Fibres
Cross linked Fibrin fibres
Ca++
PROTHROMBIN
THROMBIN
Ca++
1
2
3

14. C. BLOOD COAGULATION: MECHANISM
2 PROTHROMBIN TO THROMBIN
Plasma protein
Alpha2 globulin
MW 68,700
15mg/dl
Unstable protein
Made in liver
Needs Vitamin K
Vit K def --> bleeding
3 FIBRINOGEN TO FIBRINOGEN MONOMERS
MW 340,000
100-700mg/dl
Formed in Liver
1dl = 100ml
Polymerize to form long fibrin fibres
Initially weak bonds; clot is weak
Fibrin stabilizing factor
Covalent bonds
Cross linking; meshwork formed
Clot retraction
Activated by thrombin

15. C. BLOOD COAGULATION: MECHANISM
Clot retraction:serum is formed; does not coagulate (lacks coagulation factors)
Occurs because of platelets which release fibrin stabilizing factor, contractile proteins
(actin, myosin) cause contraction and compresses the clot [activated by thrombin and Ca
released from golgi and mito. of platelets]----> hemostasis
Cascade of blood clotting factors and formation of PROTHROMBIN ACTIVATOR
1
Viscious cycle relying on +ve feedback mechanism
Thrombin is very important
Triggers
1. Trauma to vascular wall
2. Trauma to blood
3. Contact of blood with endothelial cells,
collagen or tissue outside blood
PROTHROMBIN ACTIVATOR
Activation of several clotting factors and prothrombin to thrombin
Inactive proteolytic enzymes

16. CLOTTING FACTORS SYNONYMS
Fibrinogen -------> Factor I
Prothrombin -------> Factor II
Tissue factor -------> Factor III; thromboplastin
Ca -------> Factor IV
Factor V -------> Proaccelerin; labile factor ; Ac-globulin (Ac-G)
Factor VII -------> Serum prothrombin conversion accelerator (SPCA)
Factor VIII -------> Antihemophilic factor (AHF); AHG; Antihemophilic factor A
Factor IX -------> Plasma thromboplastin component (PTC); Christmas factor;
Antihemophilic factor B
Factor X -------> Stuart factor
Factor XI -------> Plasma thromboplastin antecedent (PTA); Antihemophilic factor C
Factor XII -------> Hageman factor
Factor XIII -------> Fibrin stabilizing factor
Prekallikrenin -------> Fletcher factor
HMW kininogen -------> Fitzgerald factor; HMWK
Platelets

17. Cascade of blood clotting factors and formation of PROTHROMBIN ACTIVATOR
1
Extrinsic Pathway
Starts with damage
to vascular walls and
tissues and it comes
in contact with blood
Intrinsic Pathway
Starts in blood itself
Exposure of blood to
collagen
Contact activation pathway
Tissue factor pathway
Tissue factor
VII ------> VIIa
X-------> Xa
Ca
Prothrombin activator
Prothrombin ----->
Ca
Fibrinogen -----> Fibrin -----> cross linked clot
FSB
Trauma
Ca
XII -------> XIIa
XI -------XIa
IX -----------> IXa
X --------> Xa
Ca
VIII
VIIIa
Ca; platelet
phospholipid
Va <---- V
HMWK
prekallikrenin
Thrombin

18. FSB
Tissue factor
pathway inhibitor

19. Interaction between Extrinsic and Intrinsic pathway
•Tissue factor initiates extrinsic factor and contact of factor XII,
platelets with collagen initiates intrinsic pathway
•Speed of pathways is regulated by amount of tissue factor (traumatized
tissue) and Factor V, VII, and X in blood.
•Intrinsic pathway is slower (1-6min) than extrinsic (15sec)

20. Prevention of Blood Clotting
• smoothness of endothelial cells; prevents contact with collagen and intrinsic
pathway
•Layer of glycocalyx which repel clotting factors
•Protein thrombomodulin on endothelial membrane binds to thrombin and
slows clotting and also forms protein C which inactivates Factor VIII and V
•On trauma endothelial wall and glycocalyx-thrombomodulin layer is damaged
and factor XII and platelets are activated they come in contact with collagen
and intrinsic pathway starts

21. Prevention of Blood Clotting
Anticoagulants in blood
1. Fibrin fibers (remove thrombin from blood by binding to it; prevents
spread of clot)
2. Alpha globulin; antithrombin III or antithrombin heparin cofactors’
binds to fibrin not bound to thrombin
3. Heparin: conc. in blood is low;used as an intravascular coagulant.
Combination with antithrombin it becomes a coagulant. In presence of
heparin, thrombin is removed and blood clotting factors cannot act.
Also produced by mast cells and basophils and prevent formation of
clots.

22. Plasma produces t-PA
Plasminogen (pro fibrinolysin )-------------> Plasmin (activated; fibrinolysin)
Plasmin is like trypsin; digests fibrin fibres, fibrinogen, Factor V,
VIII, prothrombin, Factor XII.
Injured tissue release t-PA (tissue plasminogen activator). It is
released when clot stops bleeding, plasminogen to plasmin; removes
unnecessary clots from tiny peripheral vessels.
Lysis of Blood Clot

23. BLEEDING DISORDERS
1. Vitamin K deficiency
2. Hemophilia
3. Thrombocytopenia (platelet deficiency)
1. Vitamin K deficiency: causes decreased Prothrombin, Factor IX, Factor X, Factor VII
All blood clotting factors are formed in LIVER
HEPATITIS,
CIRRHOSIS, bleeding tendency due to depression of clotting
ACTUTE YELLOW ATROPHY factors
Vit K involved in formation of clotting factors in Liver (Factor VII, X, IX, prothrombin,
Protein C)
Vit K def leads to bleeding tendency
Vit K is synthesized by intestinal bacteria. Gastrointestinal disease fats are poorly absorbed
and so is vit K since its fat soluble.
Liver disorder: failure of Bile secretion; poor fat digestion and absorption hence poor Vit K
absorption

24. BLEEDING DISORDERS
2. Hemophilia: caused by abnormality or deficiency of Factor VIII; hemophilia A;
classical hemophilia (85%)
1 in 10,000 males in US have classical hemophilia
15% caused by deficiency of Factor IX
Female is always carrier;transmits it to male offspring ; one X chromosome is
protective hence always males have hemophilia
Bleeding occurs only after trauma and sometimes bleeding is so mild and
unnoticiable
Factor VIII
Large
component
Small
component
Important for intrinsic pathway
Von Willebrand’s disease
Loss of large component
Purified Factor
Expensive

25. BLEEDING DISORDERS
3. Thrombocytpenia:low level of platelets; bleeding tendency from small venules or
capillaries rather than large vessels like hemophilia
Hemorrhages throught the body tissues
Small purplish blotches: Thrombocytopenic purpura
platelets fall below 50,000/ul [normal 150,000-300,000]
below 10,000/ul are lethal
Fresh whole blood transfusion or splenectomy
THROMBOEMBOLIC CONDITIONS
THROMBUS: abnormal clot in blood vessel
EMBOLI: free flowing clot in blood
Roughendothlial surface:
Arteriosclerosis, infection, trauma
Slow movement of blood causes
formation of clots when thrombin and
procoagulants are formed
Anticoagulants for commercial use: HEPARIN and COUMARINS (warfarin)