Immunohematology (Blood
Bank)
CLS 245
What is Immunohematology?
• It is the study of Antigen-Antibody reaction as
they relate to blood disorder.
How can one donation help multiple
people?
• -In modern medical treatments, patients may
receive a pint of whole blood or just specific
components of the blood needed to treat
their particular condition.
• Up to four components can be derived from
donated blood. This approach to treatment,
referred to as blood component therapy,
allows several patients to benefit from one
pint of donated whole blood.
Cont
The main transfusable blood components are:
1. Whole blood.
2. Red cells.
3. Platelets.
4. Fresh frozen plasma
5. Cryoprecipitate AHF (Antihemophilic factors).
Blood components
Fig2: The whole blood is centrifuged to
separate the blood into red cell, plasma and
Buffy coat.
Fig1: A blood sample after separation shows
the main components of a blood.
1-Whole blood:
• Whole blood contains red cells, white cells,
and platelets (~45% of volume) suspended in
plasma (~55% of volume).
2-Red cells, or erythrocytes:
• Carry oxygen from the lungs to your body’s tissue
and take carbon dioxide back to your lungs to be
exhaled.
-Note: Buffy coat has leukocytes. Thus, they have
to be eliminated to avoid complication of a blood
transfusion.
3-Platelets, or thrombocytes:
• They are small, colorless cell fragments in the
blood whose main function is to interact with
clotting proteins to stop or prevent bleeding.
• They are prepared by 2 ways:
1- using a centrifuge to separate the platelet-rich
plasma from the donated unit of whole blood.
2-Platelets may also be obtained from a donor by a
process known as apheresis.
What is Apheresis?
• Apheresis is a medical technology in which
the blood of a donor or patient is passed
through an instrument that separates out one
particular component and returns the
remainder to the human blood circulation.
Fig3: Diagram illustrating the process of apheresis.
4-Plasma:
• It is a fluid, composed of about 92% water, 7%
vital proteins such as albumin, gamma
globulin, anti- hemophilic factor, and other
clotting factors, and 1% mineral salts, sugars,
fats, hormones and vitamins.
5-Cryoprecipitated Antihemophilic Factor:
• (Cryo) is a portion of plasma rich in clotting
factors,including Factor VIII and fibrinogen. It is
prepared by freezing and then slowly thawing
the frozen plasma.
What is self-antigens?
• These are antigens that are found on human
cells, and the Immune system doesn’t
normally attack these.
Fig4: Normal or self-antigens are not attacked
by the immune system.
ABO system
• A system for classifying human blood on the b
asis of the presence or absence of two antige
ns on the red cell membrane.
there are four blood types (A, B, AB, and O).
Which Antigen or Antibody is present
in each group?
Rh system
• Rh blood group system, system for
classifying blood groups according to the
presence (+) or absence (-) of the Rh antigen.
• This system has 5 different antigens but
antigen D is the most immunogenic.
• RH antibodies are NOT naturally occurring.
They are formed by immune stimulus due to
transfusion or baby red cell during pregnancy.
Q) What will happen if the mother is
Rh negative and the fetus is Rh
positive?
To detect a blood group:
• 1-Add anti A, anti B and anti D antibody
separately to the blood sample
• 2-If there is agglutination then the test is
positive.
This patient blood group is …?
-Determine the blood group of each
patient
Patient1
Patient 2
Pateint3
Patient 4
Patient 5
Patient 6
Patient 7
Patient 8
Patient 9
ABO and Rh blood type donation
showing matches between donor and
recipient types
Nucleic acid Testing
(NAT)
• Nucleic acid test, often called a "NAT is a
molecular technique used to detect a virus or
a bacterium in the donor blood.
• Examples of pathogen detected by NAT: HIV,
HCV and HBV.
Antibody screening (Indirect coombs
test)
• The purpose of the antibody screen is to
detect red blood cell antibodies other than
anti-A or anti-B.
• These antibodies are called “unexpected”
because only 0.3 to 2 % of the general
population have positive antibody screen.
• Antibody screening test involve testing
patient’s serum against two or three reagent
red blood cell samples called screening cells
Cross match
• Cross-match test, consisting of mixing the
patient’s serum with donor RBCs.
• The two main functions of the cross-match test
can be cited as:
1- It is a final check of ABO compatibility between donor
and patient.
2- It may detect the presence of an Ab in the patient’s
serum that will react with Ags on the donor RBCs but
that was not detected in the Ab screening because the
corresponding Ag was lacking from the screening cell.
Summary of blood bank work flow
1. Accurate ABO and Rh typing of the patient.
2. Accurate ABO and Rh typing of the donor.
3. Screening tests for antibodies in the donors
and patients serum.
4. In the presence of patient antibodies,
selection of appropriate units for each patient.
5. Cross matching.
6. Accurate completion of paperwork and labels