Reagents and Methods for Testing in the Blood Bank (P) Flashcards
What are the basic grps of blood bank rgnts?
1) Rgnts that contain RBCs w/ sp Ag
2) Antiglobulins
3) Potentiators
What are the fxns of antiglobulins?
These are rgnts that detect IgG and complement on RBCs
What are the fxns of potentiators?
1) These are rgnts that enhance Ab detection
2) Primarily, these rgnts are used to test pts and donors sxs before pt is transfused
What are the tests done on RBCs?
1) ABO / Rhesus typing
2) Direct Coombs’ test
What are the tests done on serum?
1) Ab screening
2) Ab identification
3) Compatibility testing
Where are ABO anti-sera used?
These are used in ABO typing
What is the fxn of Anti-A and Anti-B?
These are used to identify a persons blood type
What is the principle / mechanism done by anti-sera?
These anti-sera are directed towards sp Ag on the surface of RBCs. Agglutination occurs when Anti-A is added to cells of a person w/c has A Ag, hence, that person is blood type A.
What is forward typing?
It is the addition of commercial antisera to cells
Rh anti-sera is also called as what?
Anti-D
Rhesus blood grp system consists of many diff what?
Many diff Ags
Among the diff Ags present in the Rhesus blood grp system, what Ag is the most significant?
D Ag
What are the purposes (or actions) of D Ag?
It is able to cause:
1) Serious hemolytic rxn
2) Hemolytic Disease of Fetus and Newborn (HDNB / HDN) (HDFN)
What is the requirement when doing ABO typing?
The blood should also be typed for the D Ag (Rhesus type)
Where are rgnt cells used?
In reverse typing
Rgnt RBCs are used as part of what?
These cells are used as a part of ABO typing procedure
What is the principle or mechanism of reverse typing?
Rgnt cells are tested w/ pt’s serum to detect the presence of Abs w/c the Ag (from the pt’s blood type) lack
What is the purpose of reverse typing?
It is used as confirmation for the forward typing procedure
True or False
Both forward and reverse typing are done concurrently
True
What is the meaning of AHG?
Anti- human globulin
What is AHG?
It’s an antisera that contains Abs directed against human globulins
What are the exs of human globulins that are directed upon by AHG?
1) IgG
2) Complement
What are the 2 basic categories of AHG?
1) Monospecific
2) Polyspecific
What are fxns of AHG?
It is used in many testing procedures such as:
1) Cross matching
2) Blood typing
3) Autoimmune diseases testing
What is the fxn of polyspecific AHG?
It is used in direct antiglobulin testing to test for the attachment of IgG / complement on the surface of RBCs
What are the components of polyspecific AHG?
1) Anti-IgG
2) Anti-C3
What is the fxn of monospecific antisera?
To differentiate bet the IgG and C3 coated on RBCs when direct antiglobulin test is (+)
Coombs’ control cells are also referred to as what?
Check cells (cc)
What are the fxns of cc?
1) This is a rgnt used by the blood bank as a control system when the AHG is (-)
2) It converts (-) result into (+) result
3) These basically checks to ensure the procedure was done correctly
What are cc?
These are commercially preped grp O (+) human RBCs coated w/ IgG Abs
*What is the process (or steps) in relation to the utilization of cc?
1) Add Coombs’ control cells to any (-) AHG test
2) Centrifuge
3) Examine for agglutination
What is the result if after addition of cc, the rxn does not turn into (+)?
The test test is considered invalid
What are the causes of invalid test because the rxn after addition of cc, did not turn (+)?
Either:
1) No AHG was added
2) The cells were inadequately washed
3) The AHG is expired
What are the fxns of screening cells?
1) These are used to detect Abs rather than ABO Abs in a person’s serum
2) These are used to detect Abs that might have been produced as a result of previous transfusion or pregnancy
What type of screening cells are used?
Grp O cells
Why are grp O cells used?
Because they lack any ABO Ag on their surface. Therefore, will not react w/ A and B Abs
What is the characteristic of grp O cells?
They come in sets of 2 - 3 vials
Each vial (present in grp O cells) can be from a what?
Single donor or pooled donors
What is the fxn of the vial that came from single donors?
They are used for persons who are about to receive transfusion
What is the fxn of the vial that came from pooled donors?
They can be used for donor testing
What is the characteristic of each vial (for grp O cells)?
Each set of vial comes w/ sheets of papers called anti-gram
What is the purpose of anti-gram?
These shows the type of Ag present on each screening cells
Panel cells are same w/ what cells?
They are same w/ screening cells
Even though that panel cells and screening cells are the same, there is still a difference present, what is this difference?
Screening cells come in vials of more than 10
What is the fxn of panel cells?
These are used for identifying Abs in Ab panel procedure
What is the component of each lot of panel cells?
Each lot of panel cells also has an anti-gram w/ antigenic profiles of each vial
What is the fxn of potentiators?
These assists in the attachment of an Ab to the sp Ag on the RC
What are the exs of potentiators?
1) Bovine albumin
2) Low-ionic strength saline
3) Polyethylene glycol
4) Enzymes
What is the fxn of bovine albumin?
It is used during incubation
What is the characteristic of low-ionic strength saline?
It is what commercial test cells are in
What is the fxn of polyethylene glycol?
It concentrates Ab
What are the exs of enzymes that acts as potentiators?
1) Ficin
2) Papain
What is the fxn of enzymes (that act as potentiators)?
These reduces (-) charge
What are the Abs that are enhanced by enzymes (w/c acts as potentiators)?
1) Rh
2) Lewis
What Abs are destroyed by enzymes (w/c acts as potentiators)?
1) Duffy
2) M
3) N
4) S
What are lectins?
These are seed extracts that have Ab specificity
What is the characteristic of lectins?
They do not contain Abs, but instead they contain proteins that react similarly to Abs
What is the fxn of lectins (in relation for them to not contain Abs, but instead they contain proteins w/c react similarly to Abs)?
Hence, they are used to identify certain blood grp Ags when they bind to CHO determinants of the Ag resulting in agglutination
What are the exs of lectins?
1) Dolichos biflorus
2) Ulex europeans
3) Vicia graminea
4) Iberis amara
What is the fxn of Dolichos biflorus?
It binds A1 Ag
What is the fxn of Ulex europeans?
It binds H Ag
What is the fxn of Vicia graminea?
It binds N Ag
What is the fxn of Iberis amara?
It binds M Ag