Serum Proteins and associated disorders - Part 2 Flashcards
Objectives: i.Describe how plasma proteins can be separated by electrophoresis and classify plasma proteins based on electrophoreticmobility ii.Describe the functions of serum albumin and globulins iii.Indicate the role of proteins of the complement system iv.Predict the common causes of hypoalbuminemia(liver disease, nephroticsyndrome, protein malnutrition) and explain the biochemical basis for the occurrence of edema in hypoalbuminemia v.Distinguish the functions of proteins that are foun
What is alpha fetoprotein (AFP)?
an a1globulin that is abundant in fetal plasma and may have a function similar to albumin in fetal life.
Describe AFP in adults.
- AFP is low in healthy adults but is used as marker for liver cancer or ovarian cancer
- In pregnant women it is used as marker for fetal abnormalities
Low maternal serum AFP is an indicator of what?
Down Syndrome
High maternal serum AFP levels is an indicator of what?
Fetal neural tube defects
In areas of inflammation, what happens to transcortin binding?
Binding is reduced and more cortisol is taken up into cells
What is the role of Retinol Binding Protein (RBP)?
- transports retinol (vitamin A) in blood from the liver to the peripheral tissues.
- Retinyl esters are stored in the liver.
What is one of the largest serum proteins? What does it act as?
-Alpha2 Macroglobulin
-acts as Protease inhibitor
(Proteases such as: Plasmin; Thrombin)
What type of activity does Ceruloplasmin, an alpha 2 globulin, have?
- Ferroxidase activity
- thus helps in the oxidation of Fe2+ to the Fe3+ form and its incorporation into transferrin
Haptoglobin, an alpha 2 globulin, binds what?
Free hemoglobin in circulation
How is the alpha 2 macroglobulin levels in nephrotic syndrome? Why?
- 10 fold elevated;
- Nephrotic syndrome leads to protein loss in urine. Albumin levels decrease but a2-macroglobulins are retained due to large size.
What is ceruloplasmin?
a copper containing a2-globulin plasma protein
What is characteristic of ceruloplasmin levels in WIlson’s disease?
Low
What causes Keyser-Fleischer rings?
Due to less attachment of copper to ceruloplasmin, copper accumulates in tissues.
Can Haptoglobin-Hemoglobin complex be excreted by the kidneys?
No, thus preventing loss of hemoglobin (iron and globin)
When do you find low serum free haptoglobin levels?
In patients with acute hemolysis (as haptoglobin complexes to hemoglobin) and can be used to monitor patients with hemolytic anemia.
What is transferrin?
- a b-globulin which transports iron in the ferric form
- transports iron between intestine, liver, bone marrow and spleen
How many Fe3+ atoms can each transferrin bind?
2
What is Hemopexin?
a b-globulin that binds to free heme in blood circulation and prevents the loss of iron by the kidneys.
In regards to acute phase proteins, what change is found as response to injury, like infection, extreme stress, burns, major crush injury, or allergy
Acute phase proteins:
are groups of serum proteins that are
•increased in serum (“positive” acute-phase proteins, acute-phase reactants)
or
•decreased (“negative“ acute phase proteins, like albumin) in response to any inflammatory disorders.
What can lead to an increase of the a2-globulin fraction?
- Ceruloplasmin facilitates ferritin action and
- haptoglobin binds serum hemoglobin.
- Both proteins lead to inhibition of iron uptake by microbes.
What can lead to an increase of the alpha1-globulin fraction?
Increased synthesis of the inhibitor of neutrophil elastase, a1-antitrypsin
What are normally not found in the serum but are synthesized and released during inflammation?
- C-reactive protein (CRP)
- serum amyloid A
What are gamma globulins and what are they produced by?
immunoglobulins or antibodies which are produced by activated B lymphocytes (plasma cells)
When are gamma-globulins elevated?
in liver disease, especially cirrhosis
What is the first antibody to be produced in response to an antigen?
IgM
When is IgG produced?
IgGis the antibody produced on repeated exposure to the same antigen and also crosses the placenta and confers immunity to the fetus and newborn
Which immunoglobulin is secreted in response to an allergen?
IgE
What is multiple myeloma?
a tumor of the plasma cells (activated B lymphocytes)
What is multiple myeloma characterized by?
presence of high amounts of a single type of immunoglobulin (monoclonal Ig)
