Coombs Test Flashcards
Sensitization of red cell can occur
in vitro or in vivo
The use of AHG serum to detect sensitization of red cell in vitro can be
DAT and IAT
Sensitization of rbc may be with
Igg or complement
In prder for agglutination to occur an additional of
Anti antibody or anti complement
In order for agglutination to occur up addition of anti ab or anti compelemnt which reacts with
Fc portion of igg ab or with c3b or c3d component of compelement
This will form a bridge between the Ab or complement coating the red cell causing what
Agglutination
The coating of red cell can occur in vivo or in vitro incubating at and with what
37 deg and with serum containing Ab
Injecting human serum or purified globulin into rabbits goats or sheep
Classic method or hyperimmunization of rabits
The rabbits produce what
Ab to human globulin or anti Igg or against human complement or anti complement
This results to the production of polyclonal Ab which recognize different epitopes
Classic method or hyperimmunization of rabbit
This can be used to produce monoclonak ab which are derived from one clone of plasma and recognize a single epitope
Hybridoma technology or kohler and milstein echnique
Lab animals in hybridoma techniques used what
Rats
These rats are immuniEd with
Purofied human globulin
After suitable immune response i hybridoma technique mouse spleen containing ah secreting lymphocytes are fused with
Myeloma cells
Are scree for ab with the required specificity and affinity
Hybridomas
The ab secreti clones are then propagated in tissue culture or inoculating into mice in which case the ab is collected as
Ascites
Types of AHG Rgt
Polyspecific anti human globulin
Monospecific rgts
Anti igg alone or anti c3b-c3d alone
Monospecific rgt
Blend of anti igg and anti c3b c3d
Polyspecific anti human globulin
Strong complement activator
Igm
Igm coating of cells comes from the presence of
C3 coating the cells
In dat cells are coated
Invivo
Cells are washed to remove
Unbound globulin
Addition of anti human globulin promotes
Agglutination after centri
Detects in vivo sensitization of rbc with igg or complement components
Dat
Clin condition that can cause invivo coaating of rbc with ab or complements are
Hdn
Htr
Autoimmune HA and drug induced HA
When recipient ab coat donor rbc
Htr
Where auto ab coat individual rbc
Autoimmune HA
When the maternal ab coat fetal rbc in mothers circulation
Hdn
Ex of alloimmune hemolysis
Htr and hdn
Warm and cold ab
Under htr of alloimmune hemolysis are
Rhesus D, abo, anti kell, rhesus c, E
Other blood groups incompatibility
RhC, Rhe. kidd, duffy, MN, P
Under autoimmune HA ARE
Warm an and cold Ab
Under warm Ab
Idiopathic
SLE
Evans syndrome
Antiplatelet ab and HA
Evans syndrome
Cold ab
Idiopathic and hemagglutinin syndrome
Infectious mononucleosis
Pch
Drug induced immune mediated hemolysis
Methyldopa
Penicillin
Quinidine
Igg mediated type ii hypersensitivity drug
Methyldopa
Igm mediated activation of classical act and membrane attac complex
Quinidine
Blood tube used in dat
Edta or citrate
If its not reactive this would occur it
Rgt deteriorated in storage
The rgt contaminated by serum
The cells insufficiently washed and serum had neutralized Ahg rgt
To determine the presence of sensitizationof red cells with igg and complement in virro
IAT
IAT done complement in vitro in the ff condition
Compatibility testing
Screening and detection of unexpected ab in serum
Determination of red cell phenotype K, Lea, Fya, Fyb, Jka, Jkb and subgroup rh by know pn sera
One stage method additive method in iat
Bovine albumin 22%
Pricedure of one stage method
2 drops of BVA and added in step 2 of sakine
Incubate 20-30mins at 37
As saline iat procedure
false neg results in dat and iat
Failure to wash rbc Improper storage Not adding AHH Improper centri No of cells present
Too many cells will give
Weak reaction
Few dells will give
Impair reading of agglutination
Globulins are not bound to rbc will neutralize
Ahg rgt
The optimum ratio is
80 parts ab to 1 part ag
Ab saturating all ag sites, no ab forming cross linkages between cells no agglutination
Prozone ab excess
Ab and ag present in optimum ratio agglutination formed
Zone of equivalence
Too many ag, any agg is hidden by masses of unagglutinated ag
Zone of Ag excess post zone
In dat, all samples neg at ahg phase should be
Incubated at room temp for 5’ins to maximal sensitivity needed for compliment
Iat serum or rbc loss reactivity if
Improperly stored
Plasma used instead of serum can kead to failure to
Detect ab depending kn the presence of active complement anti jka and jkb
In iat this can affect attachment of ab or complement
Temp and incubation
In iat an optimal prep of serum to cells should be achieved by
2-3 drops pf serum to 1 drop 5% rcs
In fp ditry glasswares may cause
Clumping of cells
A positive dat from a clotted sample should be
Repeated on edta sample
In fpa datSamples collected from infusion line may have
Complement present on cells
Cells with a posituve dat will give a pos reskt in any
IAT procedure
To show thta test were washed and no neutralization or rgt deterioration gas occur
Coombs cells
It is used as as posituve indicator in coombs test
Ab coated cells
Failure of igg sensitized cells to agglutinate inducated
Original neg antiglobulin test result is not valid and must repeated
Uwed to detect red cell semsitized with igg alloAb, igg autoAb or complement components
Antiglobulin test
