Quiz 4: Proteins and the Renal System Flashcards
(25 cards)
Proteins in Urine
- Albumin (mw 66 000) is too large for reabsorption.
* Proteins with mw 15,000 to about 40,000 pass freely into the urine when they are not conserved through reabsorption.
Proteinuria
• Albumin in urine suggests defects in glomerular filtration. (RI = 20 - 250 mg/day)
- Detected via dipstick (albumin binds to pad)
- Confirmed with: Test for renal tubular function, Immunoassay (ELISA, EIA)
Tubular Proteinuria
• Low mw (15k - 40k) proteins in the urine reflect defects in reabsorption
Globulin Detecting Methods
• Alpha1 antitrypsin: acute phase protein that neutralizes trypsin proteins that can damage tissues.
- Important genetic deficiency leads to severe lung disease.
• Alpha1 fetoprotein: protective in the fetus and an important tumor marker in adults.
Globulin Proteins
• Alpha1 acid glycoprotein (orosomucoid) • Alpha2 macroglobulin • Beta2 microglobulin • Complement • Fibrinogen • C-Reactive Protein • •
Alpha1 acid glycoprotein (orosomucoid)
Increased during inflammation
Alpha2 macroglobulin
Increases in serum in kidney disease due to its large size.
Beta2 microglobulin
Small size, freely cleared by renal glomerulus and 99% reabsorbed
Sensitive indicator of kidney damage when levels in serum are elevated
Complement
Group of proteins involved in the immune response (see immunoglobulins)
Fibrinogen
Involved in clot formation, found between beta and gamma bands on electrophoresis of plasma, not found in serum.
C-Reactive Protein
Inflammatory response protein
• CRP binds to bacteria (opsonization) which promotes binding of complement which leads to phagocytosis of bacteria.
• One of the first acute phase proteins to rise in infections and immune response diseases (RA, viral infections etc)
Bence Jones Proteins, Detection
- Light chains of Ab in urine, found in multiple myeloma patients
- Methods for detection: electrophoresis and/or specific immunoassays for light chains.
Paraproteins (Myeloma Detection)
- Abnormal light chains
* Lower mw of light chains compared to full immunoglobulins results in their secretion into the urine.
Ab Breakdown (Papain and Pepsin)
1) Reduce and Pepsin: Fab’
2) Papain: Fab and Fc
3) Pepsin: F(ab’)2 and pFc’
Immunoglobulin Detection
- Electrophoresis (including various forms of Immunoelectrophoresis)
- nephelometric
- turbidimetric
- EIA
- RID
Locations of Immunoglobulins in the Body
IgG: major function is neutralization of toxins like virus, bacteria etc
IgM: first early response to an antigen.
IgE: trace amounts in serum, mostly from Mast Cells’ histamine release during immune response
IgA: present in secretions
IgD: auto-regulation
Conditions Causing Immunoglobulin Deficiency
Defective Synthesis
Lymphoid malignancies
Toxic reaction to drugs
Renal failure Diabetes
Conditions Causing Immunoglobulin Increase
- B-lymphocyte lymphomas
- Lymphocytic leukemia
- Waldenstrom’s macroglobulinemia
- Multiple Myeloma (neoplasm of plasma cells)
Polyclonal: Normal response to infections
Monoclonal (Paraproteins):
Single clone of plasma cells produce immunoglobulin of identical structure.
Plasma cells also may produce increased amounts of light chains (lambda chains) and rarely heavy chains (kappa chains)
Electrophoretic Spread of Globulins
(-) Gamma Globulins - Beta Globulins - Alpha Globulins - Albumin (+)
Moving toward the Anode
Nephrotic syndrome
In which albumin is lost, giving low Alb staining and alpha2/ beta bands in SEP are increased due to retention of proteins like alpha2 macroglobulin.
Acute-Phase Reactant Pattern in SEP
Seen when albumin is decreased and alpha and beta bands are increased. CRP found in beta band.
Liver Disease in SEP
Shows decreased albumin, and increase in gamma globulin band.
High Resolution Electrophoresis (HRE)
Increases the number of bands from 5 to 12. Uses modified buffer, agarose, temperature control and high voltages.
Capillary Electrophoresis (CE)
Separates proteins inside thin capillaries (< 1 micron) under high voltage (> 20 000 vdc).
24hr Urine Testing
Quantitatively tested using Sulfsalicyclic Acid, Trichloroacetic Acid, Benzethonium chloride and Coomassie Brilliant Blue
