2. Plasma Proteins
Dr. Sara Mariyum

4. Centrifuged Blood Sample
Add anticoagulants (heparin, potassium oxalate)
Centrifuged Blood Sample

5. Components of Plasma Blood plasma Consists of: Other components:
Water 90%
Plasma Proteins 6-8 %
Electrolytes (Na+ & Cl-) 1%
Other components:
Nutrients (e.g. Glucose and amino acids)
Hormones (e.g. Cortisol, thyroxine)
Wastes (e.g. Urea)
Blood gases (e.g. CO2, O2)

6. Separation of Components
Plasma = Less Dense
Platelets / WBCs
RBCs
More Dense

7. Plasma vs. serum Anticoagulated Clotted serum= plasma - fibrinogen
Plasma is the liquid, cell-free part of blood, that has been treated with anti-coagulants.
Serum is the liquid part of blood AFTER coagulation, therfore devoid of clotting factors as fibrinogen.
Anticoagulated
Clotted
serum= plasma - fibrinogen

8. Origin Liver ( except immunoglobulin's) Derived from dietary protein
Normal level
6.3 to 8 gm/dl

9. TOTAL PLASMA PROTEINS
The normal serum protein level is g/L. The type of proteins in plasma include: a. Albumin b. Globulins α− globulin: α1 & α2−globulins β− globulin: β1 & β2 globulins γ− globulins c. Fibrinogen

10. Under different pathological conditions the protein levels depart from the normal range
Over 300 proteins have been detected in plasma

11. General functions of plasma proteins include:
Tissue formation
Viscosity
Transport
Maintaining plasma osmotic pressure
Buffering pH changes
Immunity
Enzyme activity

12. Clotting
The acute inflammatory response
Precursors of active substances

13. Transport: Transferrin transports iron.
Ceruloplasmin transports copper.
Albumin transports fatty acids, bilirubin calcium, many drugs etc.
Transcortin transports cortisol and corticosterone

14. Retinol binding protein transports retinol.
Lipoproteins transport lipids.
Haptoglobin transports free haemoglobin.
Thyroxin binding globulin transports thyroxin

15. Tissue formation Dynamic equilibrium Continuously replenished
10 to 12 grams of albumin

16. Viscosity
Resistance to the blood flow
Hyper viscosity syndrome

17. Osmotic regulation:-
Plasma proteins are colloidal and non-diffusable and exert a colloidal osmotic pressure which helps to maintain a normal blood volume and a normal water content in the interstitial fluid and the tissues.

18. Albumin content is most important in regulation of colloidal osmotic or oncotic pressure. Decrease in albumin level results in loss of water from blood and its entry into interstitial fluids causing edema

19. Blood clotting:-
Many factors are involved in clotting mechanism and prevent loss of excessive amount of blood. e.g. clotting factors IX, VIII, thrombin, fibrinogen etc.
An excess or deficiency leads to a disease. e.g hemophilia, thrombus formation.

20. Anticoagulant activity (thrombolysis):
Plasmin breaks down thrombin and dissolves the clot
Buffering capacity: -
Proteins in plasma help to maintain acid-base balance

21. Immunity
Gamma globulins
Complement system

22. Precursors of active substances
Hydrolyzed to liberate active biological products
Kinin kininogen
Angiotensin angiotensinogen

23. Hormones Protein in nature circulate in plasma PTH, insulin, glucagon
GIT

24. Enzymes Diagnosing disease
Physiological importance ( ACE, renin , plasmin)

25. Cytokines Non antibody proteins Regulation of growth, development
Mediation of inflammatory response

26. Measurement of plasma proteins
A) Quantitative measurement of a specific protein:
by chemical or immunological methods
B) Semiquantitative measurement by electrophoresis:
Proteins are separated on the basis of their electrical charge.

27. In normal cases, electrophoresis separates the proteins into five broad fractions:
Albumin,
α1-globulin,
α2-globulin,
β-globulin
γ-globulin
Each of the globulin fractions consists of a mixture of several proteins

28. Amount of protein
Mobility
albumin
globulins + -

29. Protein Electrophoresis- +
Albumin a a b g
Electrophoresis pattern for normal serum proteins

30. C-Reactive Protein ( CRP)
Electrophoretic BAND
Proteins
Albumin
a1-globulin
a1-Antitrypsin
Prothrombin
a1-Fetoprotein (AFT)
a2-globulin
Ceruoplasmin
Haptaglobin
a2-macroglobulin
b- globulin
C-Reactive Protein ( CRP)
Transferrin
b2-microglobulin
g-globulin
Immunoglobulins
(A, G, M, D & F)

31. Prealbumin
Prealbumin migrates faster than albumin in the classic electrophoresis.
It is the transport protein for:
- Thyroid hormones
- Retinol (vitamin A)
Prealbumin is decreased in:
Liver disease
Nephrotic syndrome
Malnutrition

32. Albumin
Albumin is present in higher concentrations than other plasma proteins
Albumin is synthesized in the liver & has a half-life of 20 days.
Very small amounts of albumin cross the glomerular capillary wall.

33. Accordingly, no more than traces of albumin
may normally appear in urine that can not be
detected by ordinary laboratory means.
Albuminuria :
In this case, albumin can be detected in urine by ordinary laboratory means due to physiological or pathological conditions.

34. 1- Osmotic pressure: Functions of albumin:
Albumin is responsible for ~ 80% of the
plasma osmotic pressure.
It is a major determinant of the distribution of
fluids between intravascular & extravascular
compartments.
Hypoalbuminemia leads to edema.
2- Buffering.

35. 3- Transport: bound to albumin e.g. Lipid-soluble substances
Many substances are transported in the blood
bound to albumin e.g.
Lipid-soluble substances
Hormones e.g. thyroid hormones & steroid hormones
Calcium
Drugs e.g. salicylates
Free fatty acids (FFA)
Billirubin

36. Colloid osmotic pressure
Low albumin, causing edema.

37. Causes of Albumin Deficiency
Liver diseases (cirrhosis) – decrease in the ratio of albumin to globulins
Protein malnutrition
Excessive excretion by kidneys (renal disease)

38. GLOBULINS
Heterogeneous group can be separated into different fractions on the basis of their electrophoretic mobility and sedimentation coefficient: α1-Globulin α1-Fetoprotein α1-Antitrypsin α2-Globulin α2-Fetoprotein Haptoglobin β-Globulin Transferrin Ceruloplasmin γ-Globulin Antibodies (immunoglobulins)

39. Positive Acute Phase Proteins
Stresses increases the levels of some of plasma proteins as occur in infection, inflammation , malignancy, trauma or major surgery.
These proteins are termed acute phase reactants and their synthesis is a part of body’s response to injury.
1-Antitypsin
Haptoglobin
Ceruloplasmin
Fibrinogen
C-reactive protein

40. Acute phase reactants (APRs)
Their levels change during acute inflammatory response
Cause conditions where there is:
the destruction of cells
the reversible cell damage and subsequent repair
the metabolic activation of certain cells (immune cells)
APRs concentration changes in:
infection
surgery
injury
cancer

41. α1-antitrypsin Main globulin of α1 fraction (90 %)
Synthesized in the liver in hepatocytes and macrophages
glycoprotein, highly polymorphous (≈75 forms)
Function:
Main plasma inhibitor of serine proteases (trypsin, elastase)

42. Haptoglobin (Hp) 2- globulin, tetramer a2b2 chains
Exists in 3 polymorphic forms
Functions:
binds free hemoglobin and delivers it to the reticuloendothelial cells
complex Hb-Hp is too large to pass through glomerulus  prevention of loss of free Hb (and Fe)
Free Hb passes through glomerulus, enters tubules and tends to precipitate there  kidney damage

43. Transferrin Transferrin is a β-globulin It binds free iron in serum
Normally it is about one third saturated with iron
Transferrin levels are decreased in:
liver disease (e.g. cirrhosis)
Chronic infections
Nephrosis
Congenitalatransferrinaemia
Increased serum transferrin levels occur during increased transferrin synthesis caused as a result of iron deficiency anemia

44. Fibrinogen
Synthesized in the liver.
Its function is to form a fibrin clot (when activated by thrombin)
Its level rises with pregnancy and the use of oral contraceptives
Decreased values generally reflects extensive coagulation during which the fibrinogen is consumed.

45. Ceruloplasmin Synthesized by the liver
Contains over 90% of serum copper
It is important in acute phase response as it is able to inactivate reactive oxygen species (ROS) that produce tissue damage
It is important for iron absorption from the intestine.
Plasma levels are usually low in Wilson’s disease in which copper is accumulated in the liver leading to cirrhosis , and in the basal ganglia of the brain.

46. C-Reactive Protein (CRP)
It is an acute-phase protein synthesized by liver
It precipitates the polysaccharide (fraction C) of pneumococcal cell walls
It is important for phagocytosis .
Very large increase in plasma CRP occurs in many inflammatory conditions e.g., rheumatoid arthritis.
CRP measurement with a sensitive assay (Ultra-sensitive CRP) is used for risk assessment of patients with ischemic heart disease.

47. Immunoglobulins Immunoglobulin(Ig)/antibody(Ab):
Glycoprotein molecules that are produced by plasma cells in response to an immunogen and which function as antibodies, mostly associated with γ fraction.

48. General Functions of Immunoglobulin
Antigen(Ag) binding
- Ig binds to a specific antigenic determinant
Effector functions
- Complement activation
- Binding to various cells such as phagocytic cells, lymphocytes, mast cells: antibody-mediated phagocytosis or antibody-dependent cell-mediated cytotoxicity (ADCC).

49. 1 Define origin of plasma proteins
2 Classify plasma proteins
3 Enumerate functions of plasma proteins