PRINCIPLES OF SEROLOGIC REACTIONS

Question 1

Aggregation of PARTICULATE/INSOLUBLE antigens

Answer 1

Agglutination

Question 2

Aggregation of SOLUBLE antigens

Answer 2

Precipitation

Question 3

Cells carrying antigenic molecules on their surfaces

Answer 3

Particulate Antigens

Question 4

Clumping of particles; Presence of lattice formation

Answer 4

Agglutination

Question 5

2 Stages of Agglutination

Answer 5

1. Sensitization

2. Lattice formation

Question 6

Initial binding of Ab-Ag complex; No visible reaction

Answer 6

Sensitization

Question 7

TRUE or FALSE: Sensitization is dependent on the nature of Ab&Ag surfaces and on the binding of the antibodies to the epitopes.

Answer 7

TRUE

Question 8

TRUE or FALSE: Sensitization is irreversible.

Answer 8

FALSE

Question 9

Factors affecting Sensitization:

Answer 9

1. Particle charge
2. Antibody type
3. Antigen-to-antibody ratio
4. Antigenic determinants
5. Physical conditions (pH, temp., duration of incubation)

Question 10

This refers to the net negative charge on the surface of inert particles (RBCs, latex, bacteria)

Answer 10

Zeta potential

Question 11

Clustering of ions present in the cellular environment around antigens
Neutralizes the opposite charges of Ab & Ag

Answer 11

Ionic cloud

Question 12

Decreases the ionic strength of the reaction and the zeta potential of inert particles

Answer 12

Low ionic strength saline

Question 13

Charges of ions are remedied by ______; promotes Ab-Ag binding

Answer 13

Centrifugation

Question 14

Promotes cross-linking of Ab & Ag

Answer 14

Enzymatic treatment

Question 15

Best agglutinin because of their large size and multi-valency

Answer 15

IgM

Question 16

Too small to overcome the electrostatic forces present in the ionic cloud

Answer 16

IgG

Question 17

Used to enhance the reaction for IgG-mediated agglutination

Answer 17

Anti-human globulin (AHG) methods

Question 18

TRUE or FALSE: The fewer the antigenic sites, the more effective in stimulating sensitization.

Answer 18

False

Question 19

TRUE or FALSE: The number and placing of antigenic sites affect sensitization.

Answer 19

True

Question 20

pH of medium used during sensitization

Answer 20

6.5-7.5

Question 21

At _____ pH, high electrolyte conc. will act on the net negative charge of particles, thus leading to binding.

Answer 21

Neutral

Question 22

Cold-reacting antibodies

Answer 22

IgM

Question 23

Warm-reacting antibodies (37 deg. Celsius)

Answer 23

IgG

Question 24

15-60 mins.

Answer 24

Range of incubation time

Question 25

Visible phase of agglutination

Answer 25

Lattice formation

Question 26

Establishment of cross-links (interchange of hydrogen bonds) between sensitized cells and antibodies, resulting in agglutination

Answer 26

Lattice formation