BLOOD GROUPS

DR VIKAS JAIN
ASSISTANT PROFESSOR
SIARAM,BHOPAL
The membrane of human RBCs contains a variety of blood group
specific antigens,also called agglutinogens.More than 30 such
antigens are known but a few of them are of practical
significance.These antigens enable the blood group of different
indivisuals to be differentiated.

The chief blood groups are :

1.Classical ABO blood groups.
2.Rhesus (Rh) blood group.
3.M and N blood group.
Other blood groups include –
1.Auberger group,2.diego group,3.duffy group,
4.Lutheran group,5.kell group, 6.I group ,7.kidd group,
8.Sulter group. 9.Xg group.
ABO BLOOD GROUPS :
Austrian scientist karl landsteiner, discovered the blood groups in
1901,and he was honored with nobel prize in 1930 for this discovery.
Determination of ABO blood groups depends upon the
immunological reaction between antigen and
antibody.Landsteiner found two antigen on the surface of
RBCs and named them as A-antigen and B-antigen.These
antigens are also called agglutinogens because of their
capacity to cause agglutination of RBCs.He noticed the
corresponding antibodies or agglutinins in the plasma and
named them anti-A or alpha antibody and anti-B or beta
antibody.
However ,a particular agglutinogen and the corresponding
agglutinin can not be present together.If present,it causes
clumping of the blood. Based on this,carl landsteiner
classified the blood groups ,later it became the
‘landsteiner’s law for grouping the blood.
LANDSTEINER’S LAW :
Landsteiner’s law states that ;
1.If a particular agglutinogen(antigen) is present
in the RBCs of a person,corresponding
agglutinin(antibody) must be absent in the
serum.
2.If a particular agglutinogen is absent in the RBCs
,the corresponding agglutinin must be present
in the serum.
Though the second part of landsteiner’s law is a
fact,it is not applicable to Rh factor.
ABO SYSTEM :
Based on the presence or absence of antigen A and antigen
B,blood is divided into four groups ;
1. “A” group
2. “B” group
3. “AB” group
4. “O” group
• Blood having antigen A belongs to A group.this blood has β
antibody in the serum.
• Blood with antigen B and α antibody belongs to B group.
• If both the antigens are present,blood group is called AB group
and serum of this group does not contain any antibody.
• If both antigens are absent,the blood group is called O group
and both α and β antibodies are present in the serum.
Antigen and antibody present in ABO
blood groups :
GROUP ANTIGEN IN RBC ANTIBODY IN SERUM

A A Anti B(β)

B B Anti A(α)

AB A and B No antibody

O No antigen Anti A & anti B

Determination of blood group :(also called
blood grouping,blood typing or blood matching)
Blood typing is done on the basis of
agglutination.Agglutination means the
collection of separate particles like RBCs into
clumps or masses.Agglutination occurs if an
antigen is mixed with its corresponding
antibody which is called
isoagglutinin.Agglutination occurs,when A
antigen is mixed with anti-A or when B antigen
is mixed with anti B.
Requisites –
1.A suspension of her/his RBC -prepared by mixing blood drops with
isotonic saline(0.9%)
2.Testing antisera –
A.Antiserum A,containing anti-A or α-antibody.
B.Antiserum B,containing anti-B or β-antibody.

Procedure –
1.One drop of antiserum A is placed on one end of a glass slide and one
drop of antiserum B on the other end.
2.One drop of RBC suspension is mixed with each antiserum.the slide is
slightly rocked for 2 minutes.the presence or absence of agglutination is
observed by naked eyes and if necessary,it is confirmed by using
microscope.
3.Presence of agglutination is confirmed by the presence of thick
masses(clumping) of RBCs.
4.Absence of agglutination is confirmed by clear mixure with dispersed
RBCs.
RESULTS -
1.If agglutination occurs with antiserum A ;
The antiserum A contains α antibody.the
agglutination occurs if the RBC contains A
antigen.so the blood group is A.

2.If agglutination occurs with antiserum B ;

The antiserum B contains β antibody.the
agglutination occurs if the RBC contains B
antigen.so the blood group is B.

3.If agglutination occurs with both antisera A

and B ;
The RBC contains both A and B antigens to
cause agglutination. And the blood group
is AB.
4.If agglutination does not occur either with
antiserum A or antiserum B ;
The agglutination does not occur because RBC
does not contain any antigen. So the
blood group is O
Rh factor :
Rh factor is an antigen present in RBC.This antigen was
discovered by landsteiner and wiener in 1940 .It was first
discovered in Rhesus monkey and hence the name “Rh
factor”. There are many Rh antigens but only the ‘D’ antigen
is more antigenic in human.
The person having D antigen are called Rh-positive and those
without D antigen are called Rh-negative .Among indian
population ,85% of people are Rh positive and 15% are Rh
negative.
Rh group system is different from ABO group system because
,antigen D does not have corresponding natural
antibody(anti- D) .however ,if Rh positive blood is transfused
to a Rh negative person anti-D is developed in that person.
On the other hand ,there is no risk of complications if the Rh
positive person receives Rh negative blood.
• The Rh antigen is called ‘D’, and its antibody is called anti-D.
• In Rh system ,Rh antibodies are of the IgG type and antigen-antibody
reaction occurs best at the body temperature,therefore the Rh antibodies
are called warm antibodies.
• These antibodies being IgG type can cross the placenta.
• Blood group antigens are the results of the action of genes which are
present in the chromosomes.
• The gene corresponding to the antigen D is also called D,when D is absent
from a chromosome,its place is occupied by the alternate
form(allelomorph) called ‘d’
• Rh gene is inherited from both the father and the mother.
• If gene D is carried by both sperm and ovum,the resulting gene
composition(genotype) of the offspring is DD.if the gametes carry D and d
respectively the result is Dd.if both gametes carry d the result is dd.
• DD (homozygous) and Dd(heterozygous) are both Rh positive ; dd
(homozygous) is Rh negative.
• Of 85% Rh positive -35% are DD,48% are Dd and 2% have some other
genotype containing D.
•Rh negative indivisuals (whose RBCs contain no D
agglutinogens),anti-D antibodies(agglutinins) are not
naturally present in the plasma,but the production of
anti-D antibodies in these Rh negative indivisuals may
be evoked by ;
1.transfusion with Rh positive blood .i.e. D-positive RBCs(0.5 ml
may be sufficient)
2.entrance of D-positive RBCs from Rh positive foetus into the
maternal circulation of Rh negative mother.
Note ; C,D and E are three common types of Rh antigens(Rh
factor).The type D antigen is widely prevalent in the population
and is more antigenic than the other Rh antigens.
Rh factor and hemolytic disease :
• the child of a Rh
negative mother
(genotype dd) and a Rh
positive
father(genotype DD)
must be Rh
positive(Dd). If Rh
positive father is Dd the
offspring may be Rh
positive (Dd) or Rh
negative(dd).
If mother is Rh negative and foetus is Rh positive ;
Serious complications may occur.RBCs containing
‘D’antigen may pass the placenta from the foetus
to the mother,either during pregnancy or small
amount of foetal blood leaks into maternal
circulation at the time of delivery. The mother
responds by forming anti-D ,which return to fetal
circulation and tends to destroy fetal RBCs.
The degree of damage done to the fetus depends on
the magnitude of maternal anti-D response and
the ability of maternal Rh antibodies to cross the
placenta.
Since sensitization of Rh negative mother by carrying an Rh
positive fetus generally occurs at birth,the first child is usually
normal ; however ,serius results may occur in the second or later
pregnancies depending on the degree of sensitivity of the mother.
If the mother has been immunized previously by a Rh
positive transfusion at any time,even in childhood,a
dangerously high response may occur during the
first pregnancy.
The changes in the fetus are termed hemolytic
disease,because ,they are due to the destruction of
RBCs by maternal anti-D.
ABO incompatibilities rarely produce hemolytic
disease of newborn,because alpha and beta
antibodies are of IgM and can not cross the
placenta.
The various forms of hemolytic disease of the newborn are ;
1.hydrops foetalis - the foetus is grossly oedematous,it either dies in utero or
if born prematurily or at term,it dies within a few hours.

2. Icterus gravis neonatorum ;

features -
(1) The infant born at term is jaundiced or becomes so in
24 hours,due to excessive destruction of
RBCs(hemolytic jaundice).
(2) There may be no anaemia at birth ,but develops in a
few days .because at birth ,excessive destruction of
RBCs is compensated for by an intense normoblastic
response of the marrow ,associated with high
reticulocyte count and presence of many nucleated
RBCs in the circulation.(erythroblastaemia or
erythroblastosis foetalis)
Free anti-D(derived from the mother) is present in the
infant’s blood for at least one week after birth and
continues to destroy the infant’s cells,though at
diminished rate at this time.
(3) There may be serious neurological lessions involving
basal ganglia.as blood brain barrier is not developed
in foetus and newborn infants,bile pigments enter the
brain and they secondarily become stained bright
yellow with bile pigments(kernicterus).it usually
develops when serum bilirubin level exceeds
18mg/dL.
(4) Liver may also be severely damaged and death may
occur from liver failure.
Treatment –exchange blood transfusion soon after birth
i.e.removing small quantities of infant’s blood successively from
IVC(by passsing a polyethylene catheter along the umbilical vein )
and replacing an equal volume of compatible Rh negative blood.
Thus,infant Rh positive RBCs prone to destruction are removed
from the circulation.

Prevention of Rh hemolytic disease –

Destruction of Rh positive foetal cells in the maternal
blood can be brought about by administering a single
dose of anti-Rh antibodies in the form of Rh-
immunoglobulin soon after child birth .this prevents
active antibodies formation by the mother.
Physiological basis of blood groups/
uses of blood grouping tests ;
1.In blood transfusion.
2.In pregnancy( Rh incompatibility).
3.Investigating cases of paternity dispute.
4.Medicolegal value.
5.Blood group antigens help in cell recognition.
BLOOD TRANSFUSION –
1.Blood loss : accidents,surgical operations
2.Blood disorders : haemophilia,purpura,clotting defects.
3.Blood diseases : severe anaemia,leukaemia,blood dyscrasias.
4.Poisoning e.g. carbon monoxide poisoning.
5.Acute infections or fever,when gamma –globulins are needed.
6.Pre or post –operatively in building up and making up the loss.
7.shocks.
 Basic rules to be observed ;
1.The plasma of the donor which contains the agglutinins can usually be
ignored,because;
(i) The donor’s plasma in the transfusion is usually diluted so by the much larger
volume of recipient’s plasma that is rarely causes agglutination even when the
titre of agglutinins against the recipient’s cell is high.
(ii) Donor’s agglutinins are also neutralized by soluble agglutinogen which are
found free in the recipient’s body fluid.
However,when the recipient plasma has agglutinins against the donor’s RBCs,the
cells agglutinate and hemolyse. Therefore,account need only be taken of the
effect of the serum agglutinins of the recipient on the cells(agglutinogens) of
the donor.
2. No Rh negative female at any age before menopause should ever be given a Rh
positive blood transfusion,otherwise she becomes sensitized by the injected Rh
positive blood and forms anti-D antibodies( she is likely to destroy
subsequently any Rh positive fetus.).in other words ,the transfusion may make
her permanently childless.
3.For effect of transfusing cell of any group into a recipient of any group( intra-group
–transfusion)
Conclusion ;
1.Group A and group B can only safely receive blood
from their own group and group O.
2. Persons of group AB have no circulating
agglutinins and can,therefore be given blood of
any type without developing a transfusion
reaction,called universal recipients.
3.Persons of group O contain no agglutinogen and
their blood can be given to anyone,therefore ,its
RBCs are not agglutinated by the members of
group,called universal donors.
 Dangers / hazards ;
1.Effect of incompatible ( mismatched) blood transfusion – signs and
symptoms occur because the recipient serum contains
antibodies(alpha,beta,or anti-D) which agglutinate the donor’s RBC.
The RBCs are first agglutinated and then undergo hemolysis. The
following types of clinical reaction occur :
(i) Inapparent hemolysis : injected RBCs are rapidly destroyed , the
recipient’s blood returning within a week or less to it’s pre-
transfusion state.
(ii) Post -transfusion jaundice-hemolysed RBCs cause increased release
of haemoglobin which gets metabolised to bilirubin producing
“haemolytic jaundice”.
(iii) Severe reaction with haemoglobinuria and renal failure.
(a) After few ml of blood has been introduced ,patient complains of
violent pain in the back or elsewhere and tightness in the chest ;
because ,agglutinated RBCs forms clumps which block capillaries.
(b) oliguria(decreased urinary output) due to ; fall in arterial blood
pressure below 70mmHg, and local vascular disturbances in kidneys.
These cause marked fall inglomerular filtration rate(GFR).
 If urine is acidic and GFR is slow,the haemoglobin which passes through
glomeruli is precipitated in the tubules as ‘acid haematin’. This obstruct the lumen
of tubules producing renal tubular damage. Later anuria sets in ( complete
absence of urine output) due to vascular disturbances involving the glomeruli.

still later,
Renal failure
Increase nitrogenous
substances and
potassium in the
body(uraemia)
(within 8-10 days)
Lethargy,coma,death
(death occurs,if more than
350 ml of incompatible
blood is transfused).
2.Mechanical overloading-of circulation produces
‘hypervolemia’specially in patients with cardiac damage.
3. chemical risks –
(i) as stored blood cells lose K+ to the external plasma,therefore
,after excessive transfusion e.g. replacement transfusion for
erythroblastosis foetalis ,death occurs due to hypercalaemia.
(ii) tetany
(iii) alkalosis-defective kidney functions.

4.Pyrogenic reactions-like fever with chills and rigors.

5.Allergic reactions-rash,anaphylactic
shock,angioneurotic edema,urticaria,serum sickness.
6.Transmission of diseases like
malaria,syphilis,AIDS,jaundice(viral hepatitis) etc.