P2: Blood Sample Preparation (Immunology)

What are the cellular components of blood?

erythrocytes (Red Blood Cells), leukocytes (White Blood Cells), and platelets.

What are the cellular components of blood suspended in?

(blood) plasma

What is the difference between blood serum and blood plasma?

blood serum is blood plasma without clotting factors

How is a blood sample taken?

venepuncture

Which veins are used for blood sampling in most large mammals?

jugular vein, caudal vein

Where are blood samples taken from in pigs?

vena cava veins, sinus retroorbitalis, jugular vein, caudal vein

Where are blood samples taken from in birds?

brachial vein (wing)

Where are blood samples taken from in laboratory animals?

vena auricularis, vena retroorbitalis, heart puncture

How is serum obtained?

from coagulated whole blood by centrifugation

What is blood serum used for in serological tests?

detect presence of specific antibodies;
detect presence of humoral components of the innate immune system;
investigate problems with the immune system

What humoral components of the innate immune system can be detected in the blood serum?

complement proteins, acute phase proteins (APPs)

What problems with the immune system can be investigated using blood serum?

autoimmune diseases; immunodeficiency disorders

What is antiserum?

serum prepared from blood of animals that have been exposed to a disease or have been immunised and developed specific antibodies

What is antiserum used for?

serological tests; treatment of an animal against a disease to which they have been exposed

What may cause haemolysis in blood serum?

pressure applied when drawing blood into the syringe through a needle may cause rupture of RBCs;
refrigeration of non-separated blood sample;
mechanical handling due to blood sample shaking

What colour is icteric serum?

dark to bright yellow

How are lipemic serum samples identified?

turbid or milky

What is the most common pre-analytical cause of lipemic serum samples?

inadequate time of blood sampling after feeding or parenteral administration of synthetic lipid emulsions

What is lyophilisation and what is it used for?

freeze-drying; best method for long-term storage of sera

How is serum depleted of complement activity?

heating to 56 C for 30 minutes

What is it called when serum is depleted of complement activity?

serum inactivation

What substances can be added to preserve serum?

sodium azide; merthiolate

What tests can be used to determine immunoglobulin concentration?

radial immunodiffusion kits, ELISA-based kits, glutaraldehyde coagulation test, zinc sulfate turbidity test

What is the glutaraldehyde coagulation test used for?

estimate the level of immunoglobulins and fibrinogen semi-quantitatively in whole blood; detects inflammatory conditions in individual animals

What happens in the glutaraldehyde coagulation test?

glutaraldehyde creates a clot with either fibrinogen or immunoglobulins in EDTA-stabilised blood by a chemical reaction between aldehyde groups in glutaraldehyde and free amino groups in fibrinogen and immunoglobulins

What is the glutaraldehyde coagulation test primarily used for?

screen neonates for possible failure to acquire colostral immunoglobulin

How are the results of the glutaraldehyde coagulation test interpreted?

reaction time is directly proportional to the concentration of fibrinogen and immunoglobulins

What is the zinc sulfide turbidity test based on?

precipitation of salts created by the chemical combination of heavier globulins and trace metal ions

How can the zinc sulfide turbidity test be interpreted?

visual assessment; spectrophotometry

How are the results of the zinc sulfide turbidity test interpreted?

degree of turbidity is directly proportional to the concentration of total immunoglobulins (not specific to IgG)