ABO

Although there are over 600 known red blood cell antigens organized into 22 blood group systems, routine blood typing is usually concerned with only two systems: the ABO and Rh blood group systems. Antibody screening helps to identify antibodies against several other groups of red blood cell antigens.

Some of the other groups are the Duffy, Kell, Kidd, MNS, and P systems

2011YT   Cartwright

2010DI   Diego

3009JK   Kidd

6008FY   Duffy

3007LE   Lewis

21006KEL   Kell

18005LU   Lutheran

47004RH   Rh

1003P1   P

37002MNS   MNSs

4001ABO   ABO

BLOOD GROUP SYSTEMS

ANTIGENS    ISBT NUMBER    ISBT SYMBOL  CONVENTIONAL NAME 

*

*

BLOOD GROUP SYSTEMS

  ANTIGENS    ISBT NUMBER    ISBT SYMBOL  CONVENTIONAL NAME 

- -

- -

- -

2

5

10

7

1

1

9

3

3

5

3

1

026JMH   JMH

025RAPH   Raph

024OK   Ok

023IN   Indian

022KN   Knops

021CROMER   Cromer

020GE   Gerbich

019XK   Kx

018H   Hh

017CH/RG   Chido/Rogers

016LW   Landsteiner-Wiener

015CO   Colton

014DO   Dombrock

013SC   Scianna

012XG0   Xg

ABO blood group antigens present on red blood cells and IgM antibodies present in the serum

Why do we have Anti-A or Anti-B Antibodies???

Viruses transmitted from the respiratory tracts of humans to

other humans drag along various antigens including ABO blood

group antigens. Prime the newborn’s immune

system.Reduces transmissibility of viruses within a population.

Population Distribution ofMajor Blood Groups

O Rh pos38%O Rh neg 7%A Rh pos34%A Rh neg 6%B Rh pos 9%B Rh neg 2%AB Rh pos 3%AB Rh neg 1%

Red blood cell compatibility table

                       AB+

           AB-

           B+

     B-

           A+

     A-

     O+

O-

AB+AB-B+B-A+A-O+O-

DonorRecipient

  

Plasma compatibility table

           O

     B

     A

  AB

AB

BAO

DonorRecipient

Other Blood Groups

No naturally occurring antibodiesImmune response requires

previous exposureWeaker titers of univalent antibodies

Why do we care?

Compatibility testing is done to avoida hemolytic transfusion reaction

If the Host or Recipient recognizesthe donor RBC surface antigens as foreign,the host will mount an immune response

to the donor RBC’s

Major Blood Groups

Rhesus47 Antigens make up the

Rhesus Blood GroupThe most significant is the

D antigen

There is no naturally occurringAnti D Antibodies

Production of Anti D in theRH negative recipient

requires previous exposureto the D antigen

(in utero or by transfusion)

If red cells are administeredto an ABO- or D-incompatible recipient,

the recipient will mount anantibody response to the foreign

RBC surface antigens

IgM is polyvalentand fixes complement

Intravascular Clumping of Donor RBC’s

Clumps and extruded RBC stromaresult in organ dysfunction

and possible death

Incidence 1:38,000 – 1:70,000Mortality 1:30

Intravascular hemolysis of donor RBC’s

Donor RBC’s coated with host antibodies

Stiffer RBC membraneSusceptible to attack by

splenic macrophages

But nointravascular clumping

Bits of Donor RBC membranelost traversing splenic sinusoids

(extravascular hemolysis)

SpherocytesDecreased RBC survival

Delayed anemiaPriming for worse reaction

What is compatibility testing?Also called pretransfusion testingPurpose:

To select blood components that will not cause harm to the recipient and will have acceptable survival when transfused

If properly performed, compatibility tests will confirm ABO compatibility between the component and the recipient and will detect the most clinically significant unexpected antibodies

Patient IdentificationMust confirm

recipient’s ID from bracelet ON the patientFull patient name

and hospital numberName of physician

http://www.usatoday.com/tech/news/techinnovations/2006-07-17-chips-everywhere_x.htm

COMPATIBILITY TESTINGCOMPATIBILITY TESTINGProcessing the specimen:Processing the specimen:

ABO Group determined (forward and ABO Group determined (forward and reverse)reverse)

D typing determinedD typing determinedAntibody screen will be performedAntibody screen will be performedABO/Rh identical or compatible blood ABO/Rh identical or compatible blood

will be made availablewill be made available

Sample IdentificationThe sample should

also have the full patient name, hospital number, and physician

Date and time of collection, phlebotomist’s initials

All of this should be on the request form and the sample

Specimen Tubes

Pink Top - EDTA Red Top – no additives

Serological Testing3 tests:

ABO/RhAntibody detection/identificationCrossmatch

ABO/Rh TypingIn the ABO typing, the forward and reverse

MUST matchIn the Rh typing, the control must be

negativeBoth of these will indicate what type of blood

should be given

Front or Front or forwardforward type using monoclonal type using monoclonal anti-A and anti-B (commercial)anti-A and anti-B (commercial)

The sample is diluted to Hct 0.08, the The sample is diluted to Hct 0.08, the commercial antibodies added & the commercial antibodies added & the test tube is centrifugedtest tube is centrifuged

The RBC’s are then examined for The RBC’s are then examined for clumping (gross observation, gel clumping (gross observation, gel suspension)suspension)

Front or Front or forwardforward type using monoclonal type using monoclonal anti-A and anti-B (commercial)anti-A and anti-B (commercial)

The sample is diluted to Hct 0.08, the The sample is diluted to Hct 0.08, the commercial antibodies added & the commercial antibodies added & the test tube is centrifugedtest tube is centrifuged

The RBC’s are then examined for The RBC’s are then examined for clumping (gross observation, gel clumping (gross observation, gel suspension)suspension)

ABO TYPINGABO TYPING

Anti A Anti B Anti A Anti B

Anti A Anti B Anti A Anti B

A B

OAB

ABO TYPINGABO TYPING

Back or Back or reverse reverse type with A and B cellstype with A and B cellsCommercially available A and B cells are Commercially available A and B cells are

added to two tubes of plasmaadded to two tubes of plasma

ABAB BB AA OO

A B A BA BA B

How do we know whether or not the host (or How do we know whether or not the host (or recipient) has antibodies to minor blood group recipient) has antibodies to minor blood group antigens?antigens?

How do we know whether or not the host (or How do we know whether or not the host (or recipient) has antibodies to minor blood group recipient) has antibodies to minor blood group antigens?antigens?

Add commercial RBC’s with known Add commercial RBC’s with known important minor antigens on their important minor antigens on their surface to host (or recipient) plasma surface to host (or recipient) plasma and centrifuge. Then incubate at and centrifuge. Then incubate at body temperature for 15-30 minutesbody temperature for 15-30 minutes

Then add rabbit antiglobulinThen add rabbit antiglobulin

Add commercial RBC’s with known Add commercial RBC’s with known important minor antigens on their important minor antigens on their surface to host (or recipient) plasma surface to host (or recipient) plasma and centrifuge. Then incubate at and centrifuge. Then incubate at body temperature for 15-30 minutesbody temperature for 15-30 minutes

Then add rabbit antiglobulinThen add rabbit antiglobulin

Antibody screenAlso called the Also called the indirect Coombs testindirect Coombs test or the or the

indirect antiglobulin testindirect antiglobulin testThe antibody screen will detect the

presence of any unexpected antibodies in patient serum

If antibodies are detected, identification should be performed using panel cells (with an autocontrol)IS37° (LISS)AHG

If recipient antibodies have coatedcommercial RBC surfaces

Rabbit antiglobulin will bind to theAntibodies and the RBC’s will clump

ANTIBODY SCREENINGANTIBODY SCREENING

Detection of unexpected clinically Detection of unexpected clinically significant antibodies against the minor significant antibodies against the minor blood group system antigensblood group system antigens

Positive in between 0 - 8% of samples Positive in between 0 - 8% of samples depending on the populationdepending on the population

2011YT   Cartwright

2010DI   Diego

3009JK   Kidd

6008FY   Duffy

3007LE   Lewis

21006KEL   Kell

18005LU   Lutheran

47004RH   Rh

1003P1   P

37002MNS   MNSs

  

*

Possibly significant minor blood groups

SCREENING TEST RESULTS

A negative antibody screen allows blood to be dispensed using an immediate spin X-match or an electronic X-match, either of which confirms ABO compatibility

A positive antibody screen requires a full antiglobulin phase X-match

CrossmatchingPurpose:

Prevent transfusion reactionsIncrease in vivo survival of red cellsDouble checks for ABO errorsAnother method of detecting antibodies

Crossmatches According to the AABB Standards:

The crossmatch “shall use methods that demonstrate ABO incompatibility and

clinically significant antibodies to red cell antigens and shall include an antiglobulin

phase”

Donor RBCs (washed)

Patient serum

No agglutination ~ compatible

Agglutination ~ incompatible

The procedureDonor cells are

taken from segments that are attached to the unit itself

Segments are a sampling of the blood and eliminate having to open the actual unit

Crossmatch Procedure if antibodies are NOT detected:

Only immediate spin (IS) is performed using patient serum and donor blood suspension

This fulfills the AABB standard for ABO incompatibility

This is an INCOMPLETE CROSSMATCHIf antibodies ARE detected:

Antigen negative units found and X-matchedAll phases are tested: IS, 37°, AHGThis is a COMPLETE CROSSMATCH

WillVerify donor cell ABO compatibility

Detect most antibodies against donor cells

Will NotGuarantee normal survival of RBCs

Prevent patient from developing an antibody

Detect all antibodies

Prevent delayed transfusion reactions

Type and Screen

Determines the ABO-Rh of the patient and the presence of the most commonly found unexpected antibodies(elimination of the crossmatch ).

Type and Screen

If an emergency transfusion is required after type and screen alone, an immediate-phase crossmatch is performed.

Blood given in this manner is more than 99% effective in preventing incompatible transfusion reactions due to unexpected antibodies.

Is the Crossmatch Really Needed?If the correct ABO and Rh blood type is

given, the possibility of transfusing incompatible blood is less than 1 chance in 1000.

ABO-Rh typing alone results in a 99.8% chance of a compatible transfusion,

The addition of an antibody screen increases the safety to 99.94%, and

A crossmatch increases this to 99.95%.

Physician responsibility in ordering uncrossmatched blood

In an emergency (ER or OR), there may not be enough time to test the recipient’s sample

It is your judgment that the risk of the patient dying from from anemia is greater than the risk of transfusing the patient without pre-transfusion testing

What can be given in an emergency?

Type-Specific, Partially Crossmatched Blood An ABO-Rh typing and an immediate-phase

crossmatchAn abbreviated format Macroscopic agglutination. This takes 1 to 5 minutes

What can be given in an emergency?Type-Specific, Uncrossmatched Blood

The ABO-Rh type Most ABO type-specific transfusions are

successful. Caution should be used for patients who have

previously received transfusions or have had pregnancies.

What can be given in an emergency?Type O Rh-Negative (Universal Donor),

Uncrossmatched Blood Type O blood lacks the A and B antigens Type O Rh-negative, uncrossmatched packed

RBCs should be used in preference to type O Rh-negative whole blood.

More than two units of type O Rh-negative, uncrossmatched whole blood, the patient probably cannot be switched to his or her blood type .

Specific Recommended Protocol1. Infuse crystalloids or colloids.2. Draw a blood sample for typing and

crossmatching.3. If crossmatched blood is not ready to give,

use type-specific or type O Rh-negative cells or type O Rh-positive cells for males or postmenopausal females without a history of transfusions.

SummaryThe crossmatch “shall use methods that

demonstrate ABO incompatibility and clinically significant antibodies to red cell antigens

If an emergency transfusion is required after type and screen alone, an immediate-phase crossmatch is performed before transfusion (an abbreviated format )

If crossmatched blood is not ready to give, use type-specific or type O Rh-negative cells