Antigen and Antibody Reactions (Agglutination Tests | P)

Question 1

What is the principle of direct agglutination?

Answer 1

The pt’s serum is tested against large, cellular Ags to screen for the presence of Abs

Question 2

In connection to direct agglutination, Ag is present on what?

Answer 2

Ag is naturally present on the surface of the cells

Question 3

What is the result of direct agglutination?

Answer 3

The Ag-Ab rxn forms an agglutination w/c is directly visible

Question 4

Slide agglutination test is used for what?

Answer 4

It is used for serotyping (ex. ABO)

Question 5

In the slide agglutination test, what is the Ag and where is it present?

Answer 5

The Ag is the isolated RBC w/c is present in the suspension

Question 6

In the slide agglutination test, where is the Ab present?

Answer 6

This is present in the sp antisera used against RBC Ags

Question 7

What is the process (or steps) of slide agglutination test?

Answer 7

1) Add a drop of antiserum to various drops of blood present in the slide
2) Mix
3) Rock the slide for approx 1 min
4) Examine for the presence of agglutination

Question 8

What is the principle of hemagglutination?

Answer 8

It detects Ab to erythrocyte Ags

Question 9

What are the principles of rxns for hemagglutination?

Answer 9

1) Sufficient concentration of Ab present -> Ab cross-link = agglutination
2) Non-reactive / insufficient Ab present = no agglutination

Question 10

*What is the general principle of rxn of hemagglutination?

Answer 10

Binding diff Ags on the RBC surface = detect Abs to Ag other than those present in the cells

Question 11

*What is utilized in Coombs (antiglobulin) tests?

Answer 11

Incomplete Abs

Question 12

What is the principle of direct Coombs test?

Answer 12

It detects Abs on RBCs

Question 13

What is the principle of rxn of direct Coombs test?

Answer 13

*Pt’s RBCs + Coombs rgnt (antiglobulin) Ag-Ab rxn

Question 14

What is the principle of indirect Coombs test?

Answer 14

It detects anti-erythrocyte Abs in serum

Question 15

*What is the process (or steps) of indirect Coombs test?

Answer 15

1) Pt’s serum + target RBCs Ag-Ab rxn

2) The present Ag-Ab rxn + Coombs rgnt (antiglobulin) more Ag-Ab rxns

Question 16

What is the importance of complement?

Answer 16

It takes part in many of the immunological rxns

Question 17

What happens to complement during the combination of Ags and Ab?

Answer 17

It gets absorbed

Question 18

What is the meaning of CF (or CFT)?

Answer 18

Complement fixation test

Question 19

What is the property of Ag-Ab complex that is used in CFT and what is its purpose?

Answer 19

The property of Ag-Ab complex to fix the complement for the identification of sp Abs

Question 20

What are the components of the hemolytic system?

Answer 20

1) Sheep RBCs

2) The corresponding Ab (amboceptor) for sheep RBCs

Question 21

What is the fxn of amboceptor?

Answer 21

It is used as an indicator w/c shows the utilization or availability of the complement

Question 22

What are the results for CFT?

Answer 22

1) If the complement is fixed = no lysis of sheep RBCs; denoting a (+) test
2) If the complement is available = hemolysis of sheep RBCs is present; denoting a (-) test

Question 23

*What is the property of complement?

Answer 23

Hemolysis

Question 24

What is the principle of CF?

Answer 24

Ab and Ag are allowed to combine in the presence of complement

Question 25

What happens if the complement is fixed by sp Ag-Ab rxn?

Answer 25

It will be unable to continue w/ indicator system

Question 26

What are the precautions that must be observed in CF?

Answer 26

1) The serum must be heat-activated
2) Stored serum becomes anti-complementary
3) Extensive QC / standardization is required to be done
4) IgM Abs should only be used

Question 27

What are the components of CFT?

Answer 27

1) Test system
a. Ag
b. Ab
c. Complement
2) Indicator system (Hemolytic system)
a. Erythrocytes
b. Amboceptor (Hemolysin)

Question 28

What is the characteristic of Ag (being present in CFT)?

Answer 28

It may be soluble or particulate

Question 29

What is the source of Ab (present in CFT)?

Answer 29

It can be found in the human serum, however, the human serum may or may not contain Ab towards sp Ag

Question 30

What is complement (present in CFT)?

Answer 30

It is pooled serum that is obtained from 4 - 5 guinea pigs

Question 31

What should be the considerations (in relation to complement) that should be considered for CFT?

Answer 31

1) The complement should be fresh or specially preserved

2) The complement activity should be initially standardized before using in the test

Question 32

Why should the complement be fresh or specially preserved for CFT?

Answer 32

Because the complement activity is heat labile

Question 33

What is the storage temp for complement since it is heat labile?

Answer 33

It should be stored at -30 DC in small fractions

Question 34

What are the erythrocytes used for CFT?

Answer 34

Sheep RBCs

Question 35

*What is the amboceptor used in CFT?

Answer 35

Rabbit Ab

Question 36

Where do the amboceptor react?

Answer 36

It reacts w/ sheep RBCs

Question 37

*How can rxn bet rabbit Ab and sheep RBCs occur?

Answer 37

In terms of preparation, the sheep RBCs are inoculated into the rabbit Ab under std immunization protocol

Question 38

What is the process (or steps; or principle) for a (+) CFT test?

Answer 38

1) Ag + Ab + complement (from serum) -> complement gets fixed (at 37 DC in 1 hr)
2) Fixed complement complex + hemolytic system -> there will be no hemolysis (at 37 DC in 1 hr) -> w/c denotes a (+) CFT test