Plasma proteins part 2

Pre-albumin

• Transerythrin + Vit A

• Transports thyroxine and T3/T4

• Decreases during liver disease, acute phase inflammation, tissue necrosis

• Marker for poor nutrition

• seen in normal CSF electrophoretic pattern

Albumin ref range

• 3.5 - 5.0 g/dL

• Increases during dehydration

• Decreases during malnutrition

a1 globulins

• Increases during acute chronic infections, inflammation, neoplastic disease, pregnancy and contraceptive use

• Decreases alpha-1-antitrypsin deficiency, emphysema

a1-antitrypsin

• Acute phase reactant, protease inhibitor, major component of the fraction

a1-fetoprotein

• Increased levels indicate risk for spina bifida, neural tube defects

a1-acid glycoprotein

• Acute phase reactant, immune response

a1-lipoprotein

• transports lipids (HDL)

a2 globulin

• Increased during infection, inflammation, nephrosis

• Decreased during acute hemolytic anemia

• Haptoglobin

• Ceruloplasmin

• a2-macroglobulin

Haptoglobin

• Acute phase reactant binds hemoglobin

Ceruloplasmin

• Acute phase reactant, oxidase activity, transport copper

a2-macroglobulin

• Acute phase reactant, inhibits proteases, major component of the a2 band in protein electrophoresis

beta globulins

• Increased during inflammation, hypothyroidism, cirrhosis, obstructive jaundice, MM, diabetes mellitus, increased transferrin in iron deficiency anemia

• Decreased in hypocholesterolemia

beta globulins lists

1. Hemopexin

2. Transferrin

3. Complement

4. Fibrinogen

5. C-reactive protein

6. Beta-lipoprotein

Hemopexin

binds heme

Transferrin beta

Transferrin binds to iron ions (Fe3+) in the bloodstream

C-reactive protein

Acute phase reactant, increased with inflammation

Beta lipoprotein

transport lipids (LDL)

gamma globulins

• Infections, multiple myeloma, immunodeficiency

• IgG, IgA, IgM, IgD, IgE - antibodies in humoral immunity

• Synthesized in plasma cells

Myoglobin increases

• Heme protein found in skeletal and cardiac muscle

• Increased in myocardial infarctions

Troponin

• Complex of three proteins (TnT, TnI, TnC) bind to the thin filaments of striated muscle

• Regulate muscle contractions

• standard for acute coronary syndrome ACS

Brain Natriuretic Peptide BNP

• Neurohormone that affects body fluid homeostasis and blood pressure

• Marker for congestive heart failure CHF

Total protein ref range

• 6.5 - 8.3 g/dL

• Measure of all proteins in plasma

Hyperproteinemia

• Positive N2 balance

• More proteins than being bound

• Increased anabolism

• Dehydration increases all fractions

Hypoproteinemia

• Starvation

• Burns

• Malnutrition/malapsorption

• Catabolism increase

• Decrease in proteins

Kjeldahl total protein

• measurement of nitrogen content

Biuret routine method

• Cupric ions complex with groups in peptide bond

• violet color proportional to number of peptide bonds

Refractometry

• refractive index reflects the concentration of proteins

• Dye binding - research method

• Coomassie brilliant blue = serum electrophoresis

Methods for protein analysis

1. Turbidity/Spectrophotometry

2. Nephlometry = binding ability

3. Chromatography

4. Electrophoresis

Albumin analysis

• Anionic dye can bind albumin and create color

• Bromocresol green BCG = binds other proteins

• Bromocresol purple BCP = more specific to albumin

Albumin / globulin ratio

• A/G ratio

• Calculation of serum albumin compared to serum globulin level

• Determine over or under production of gamma globulin

Serum Protein Electrophoresis

• Migration of charged proteins 

• Positive to negative

• gel medium

• Buffer pH 8.6

SPE order

• Positive to negative

1. Albumin

2. alpha 1

3. alpha 2

4. beta

5. gamma

Serum collection

• Plasma causes an extra peak between the beta and gamma regions due to fibrinogen

• No hemolysis

  • cause an increase in a-2 region

Ionic strength buffer

• Greatly influences the velocity of protein movement

• Decrease of IS and movement increases - more diffused

• Increase of IS and movement decreases - tighter together

• Evaporation increases IS - cover during electrophoresing

Densitometry

• Similar to spectrophotometry

• Concentration of stain proportional to absorption

• Area beneath curve = proportional to conc. of protein

Monoclonal gammopathy MGUS

• Narrow needle shaped spike

• Of unknown significance

• Typically multiple myeloma

• IgG and IgA or Waldenstroms macroglubulinemia IgM

• Spike in IgG

• Reflex test needed

Polyclonal gammopathy

• Caused by reactive processes

• Broad asymmetric peak

• Chronic infection including HIV+/AIDS

• Autoimmune/collagen vascular disease: systemic lupus erythematosus SLE, rheaumatoid arthritis RA

• Chronic liver disease

Nephrotic pattern

• Long term loss of molecular weight proteins (albumin, IgG) and retention of higher molecular weigt proteins (alpha 2-macroglobulin)

• SLE (Lupus) 

• Decreased albumin

• Increased a2

Liver disease Cirrhosis SPE pattern

• End stage liver disease

• beta and gamma is blurred = beta-gamma bridge pattern

• Decreased albumin

• Increased gamma

Acute inflammation SPE pattern

• albumin decreased

• alpha 1 increased

• alpha 2 significantly increased

Chronic inflammation SPE pattern

• antigen activated B lymphs turned to plasma cells

• increased polyclonal gamma gland

• a1, a2, gamma increase

a-1 antitrypsin deficiency

• Congenital or acquired

• secondary to liver or pulmonary diseases

• Congenital = emphysema

• no a1 to normal values

Hypogammaglobulinemia

• Decreased amount of most or all immunoglobulins

• IgA / IgG or selective kappa / lambda deficiency

• Normal --> no gamma

• Requires immunofixation

• Prone to recurrent infections

Bence jones

• Multiple myeloma

• Increase in gamma region

• Protein found in urine electrophoresis

Immunofixation

• Reflex test coupled with electrophoresis and immunochemical

• Antibody serves to fix the antigen in the gel and identify antibody

• Antibody + antigen

• IgM spike = test needed

• light chains = monoclonal gammopathies

Monoclonal proteins

• Paraproteins or M-proteins

• Intact Ig/ light chain produced by clonal proliferation of plasma cells

• 1 spike

• Bence jones = needs immunofixation test

Biclonal gammopathy

• Rarely seen in multiple myeloma

• IFE = 2 M proteins to be IgG-k and IgA-lambda

• 2 spikes

Electroosmotic flow

• Movement of buffer ions

• buffers ions migrate toward cathode

• Gamma is most affected