Lecture 7: Serum Proteins Flashcards
(41 cards)
What are the 2 major types of proteins in the blood and where are they synthesized?
- Albumin - liver
- Globulins are also synthesized in the liver except for Igs and complement
Light chains that are not bound to heavy chains are called?
Free light chains
Free light chains in urine are called?
Bence Jones proteins
What are the most common to least common serum Ig?
IgG > IgA > IgM > IgD > IgE
What is bad about cross-reactivity?
With polyclonal antibodies, there is a high chance of finding imposters a.k.a false positives
What are the structures of the different types of immunoglobins?
IgG = monomer
IgA = monomer in serum, dimer in secretions
IgM = pentamer
IgD = monomer
IgE = monomer
What are the functions of IgG?
- Activates the classical pathway of the complement system
- Binds and neutralizes viruses and toxins
- Ab-dependent cell-mediated cytotoxicity (ADCC) & intracellular Ab-mediated proteolysis
- Type 1 and 2 hypersensitivity reactions
IgG participate predominantly in which immune response?
Secondary
What are the structural differences between IgG subclasses?
Number of disulfide bonds and length of hinge region
Which IgG subclass fixes complement (most to least)?
IgG3 > IgG1 > IgG2
IgG4 does not fix complement
Which IgG subclass binds to Fc receptor (strongest to weakest)?
IgG1 = IgG3 > IgG4 > IgG2
Which IgG subclass crosses the placenta?
IgG1, IgG3 and IgG4
IgG2 does not cross placenta well
List the IgG subclasses from most to least in quantity.
IgG1 > IgG2 > IgG3 > IgG4
What are the half-lives of the IgG subclasses?
IgG1, IgG2 and IgG4 = 21 days
IgG3 = 7 days
Give 4 clinical situations of when IgG increases.
- Acute and chronic infections
- Inflammation
- Autoimmune disease
- Liver disease
Give 4 clinical situations of when IgG decreases.
- Secondary IgG hypogammaglobulinemia
a. Malignancies: lymphoproliferative disease can occupy and suppress normal bone marrow development of stem cells
b. Renal failure
c. Drugs - Abnormal loss (ex. nephrotic syndrome)
- Selective Ig deficiencies
- Combined failure of Ab and cell-mediated immunity
What is the function of IgA?
Prevents colonization by pathogens
Give 4 clinical situations of when IgA increases.
- Chronic infection
- Cirrhosis of liver
- Autoimmune disease
- Wiskott-Aldrich syndrome
Give 4 clinical situations of when IgA decreases.
- Secondary Ig deficiency ex. malignancies
- Heriditary ataxia telangicctasia
- Malabsorption syndromes
- Lymphoid aplasia
What is the function of IgM?
- 1st Ig made by B cells in fetus
- Agglutination
- B cell surface Ig that functions as a receptor for Ags on B cells
Give 4 clinical situations of when IgM increases.
- Primary biliary cirrhosis
- Viral infections
- Intrauterine infections
- In newborns, > 0.2 g/L is indicator of utero stimulation of the immune system
Give 4 clinical situations of when IgM decreases.
- Malignancy
- Selective Ig deficiency
- Primary immune deficiency
- Abnormal loss
What is the function of IgD?
Ag receptor on B cells that have not been exposed to Ag which can activate basophils and mast cells to produce antimicrobial factors
Does not bind complement
When does IgD increase?
- Chronic infections
- IgD myelomas