LECTURE 4
HEMATOLOGICAL DISORDERS DIAGNOSIS AND
TREATMENT
HEMATOLOGICAL DISORDERS
These are disorders associated with the blood or blood cells or
blood factors.
There are numerous hematological disorders and they can be
grouped as follows:
i.Transfusion and blood group incompatibility
ii.Anaemia – different types
iii.Blood cancers e.g. Leukaemia
iv.Genetic disorders of the blood system – e.g. sickle cell and
thalassaemia.
TRANSFUSION AND BLOOD GROUP INCOMPATIBILITY
DISORDERS
These disorders occur as a result of:
Immune-mediated lysis of RBCs (haemolysis) due to mismatch
in the ABO blood groups of donor and recipient.
Incompatibility of Rh blood factor in donor/recipient or
mother/foetus, leading to immune mediated lysis of the RBCs
(haemolysis).
Bacterial infection at the time of transfusion, leading to
inflammation reaction and bacterial sepsis.
Transfusion and blood group reactions may be acute or delayed
i.e. they may manifest as immediate reaction or delayed
reactions.
75
, IMMUNE-MEDIATED HEMOLYSIS OF RBCS DUE TO ABO
AND RH INCOMPATIBILITY
ABO or Rh incompatibility between donor/recipient or
mother/foetus is characterized by antigen-antibody reaction
e.g. “anti-A” antibodies of a recipient binding to “A” antigens in
donor RBCs during a transfusion
Therefore, antibodies will bind to corresponding antigens on the
RBC surface.
Consequently, this induces antibody-mediated (immune-
mediated) destruction or lysis of the.
Antibody-mediated haemolysis occurs via two mechanisms:
a.Intravascular
b.Extravascular
INTRAVASCULAR AB-MEDIATED HEMOLYSIS
Antibody-bound RBCs are lysed within the vascular system i.e.
in the blood vessels, leading to the release of haemoglobin into
the vascular system.
In this reaction, IgM and IgG antibodies bind “A” and “B” antigens
on the RBCs when there is ABO blood group incompatibility.
The resulting antigen-antibody complexes activate the classical
complement pathway.
C5b–C9 lytic complex of the complement destroys the integrity of
the RBC membrane leading to entry of ions into the RBC
The RBC eventually swells and ruptures, thereby releasing
haemoglobin into the plasma.
The haemoglobin may combine plasma proteins and excess
haemoglobin is excreted in urine.
76
HEMATOLOGICAL DISORDERS DIAGNOSIS AND
TREATMENT
HEMATOLOGICAL DISORDERS
These are disorders associated with the blood or blood cells or
blood factors.
There are numerous hematological disorders and they can be
grouped as follows:
i.Transfusion and blood group incompatibility
ii.Anaemia – different types
iii.Blood cancers e.g. Leukaemia
iv.Genetic disorders of the blood system – e.g. sickle cell and
thalassaemia.
TRANSFUSION AND BLOOD GROUP INCOMPATIBILITY
DISORDERS
These disorders occur as a result of:
Immune-mediated lysis of RBCs (haemolysis) due to mismatch
in the ABO blood groups of donor and recipient.
Incompatibility of Rh blood factor in donor/recipient or
mother/foetus, leading to immune mediated lysis of the RBCs
(haemolysis).
Bacterial infection at the time of transfusion, leading to
inflammation reaction and bacterial sepsis.
Transfusion and blood group reactions may be acute or delayed
i.e. they may manifest as immediate reaction or delayed
reactions.
75
, IMMUNE-MEDIATED HEMOLYSIS OF RBCS DUE TO ABO
AND RH INCOMPATIBILITY
ABO or Rh incompatibility between donor/recipient or
mother/foetus is characterized by antigen-antibody reaction
e.g. “anti-A” antibodies of a recipient binding to “A” antigens in
donor RBCs during a transfusion
Therefore, antibodies will bind to corresponding antigens on the
RBC surface.
Consequently, this induces antibody-mediated (immune-
mediated) destruction or lysis of the.
Antibody-mediated haemolysis occurs via two mechanisms:
a.Intravascular
b.Extravascular
INTRAVASCULAR AB-MEDIATED HEMOLYSIS
Antibody-bound RBCs are lysed within the vascular system i.e.
in the blood vessels, leading to the release of haemoglobin into
the vascular system.
In this reaction, IgM and IgG antibodies bind “A” and “B” antigens
on the RBCs when there is ABO blood group incompatibility.
The resulting antigen-antibody complexes activate the classical
complement pathway.
C5b–C9 lytic complex of the complement destroys the integrity of
the RBC membrane leading to entry of ions into the RBC
The RBC eventually swells and ruptures, thereby releasing
haemoglobin into the plasma.
The haemoglobin may combine plasma proteins and excess
haemoglobin is excreted in urine.
76
