Plasma proteins

Question 1

Serum

Answer 1

Commonly used for analysis

Blood is allowed to clot naturally and therefore the serum will be devoid of clotting factors

Question 2

Plasma

Answer 2

Occasionally used for analysis

Blood is collected with an anticoagulant and therefore cells and clotting factors remain intact

Question 3

Factors affecting plasma proteins

Answer 3

• Use of a tourniquet
• Posture
• Pregnancy
• Disease

Question 4

Protein synthesis

Answer 4

Liver = synthesises most plasma proteins

Macrophages = synthesise complement proteins

B-Cells = synthesise immunoglobulins

Question 5

Acute phase response

Answer 5

Follows inflammation, infection or injury

Leads to increased blood clotting, increased leucocytosis and plasma protein synthesis

Question 6

Acute phase proteins

Answer 6

The production of acute phase proteins is triggered by pro-inflammatory cytokines

• C-reactive protein
• a1 antitrypsin
• Ferritin
• Albumin
• Transferrin

Question 7

C-reactive protein

Answer 7

Produced during the acute phase response

Binds to bacterial capsular polysaccharide (opsonin) and activates complement

Used to assess the severity of conditions and measure the response to treatment

Question 8

a1-antitrypsin

Answer 8

Produced during the acute phase response

Binds to and inhibits proteases in the blood

Genetic deficiencies of AAT= increase risk of emphysema and liver disease

Acquired deficiencies of AAT = occur due to protein-losing disorders or pancreatitis

Question 9

Haptoglobin

Answer 9

A positive acute phase protein

Synthesised in the liver, kidney and lung

Binds to haemoglobin and sequesters iron to protect the kidney

Used to investigate haemolytic diseases and chronic liver disease, these cause a decrease in haptoglobin production

Question 10

Transferrin

Answer 10

Transports Fe3+ in the blood and facilitates cell uptake of Fe3+

Levels increase during iron deficiency

Levels decrease during malnutrition, liver disease and iron overload

Used to investigate anaemia

Question 11

Ferritin

Answer 11

Positive acute phase protein

An iron storage protein

Levels increase during iron deficiency, iron overload and liver disease

Used to investigate anaemia and monitor iron stores

Question 12

Caeruloplasmin

Answer 12

A positive acute phase protein

Binds to copper in the plasma

Converts Fe2+ to Fe3+

Levels increase during pregnancy

Levels decrease in Wilson’s disease

Used to screen for Wilson’s disease

Question 13

A-fetoprotein

Answer 13

Synthesised by the foetal liver

Absent in adults

Increases during hepatocellular carcinoma and other cancers

Used for diagnosis and monitoring of cancer

Question 14

Hypogammaglobulinaemia

Answer 14

A decrease in immunoglobulin leveles

Causes = pregnancy, haematological malignancy, protein-losing states, drugs (e.g. chemotherapy)

Can lead to recurrent infections

Severe forms of the disease include bubble-boy disease

Question 15

Hypergammaglobulinaemia

Answer 15

An increase in immunoglobulin levels

Causes = infection, liver disease, autoimmune disease, inflammatory bowel disease

Question 16

Hyperproteinaemia

Answer 16

An increase in total protein

Causes = dehydration, immunoglobulin increases