1
Etymology
The name "white blood cell“ is derived
from the fact that after centrifugation of a
blood sample, the white cells are found in
the buffy coat, a thin, typically white layer
of nucleated cells between the sedimented
red blood cells and the blood plasma. The
scientific term leukocyte directly reflects this
description, derived from Ancient Greek
λευκό (white), and κύτταρο (cell).


Leukocyte content of whole blood
averages two billion ( 2 x109 ) leukocytes
per 500 mL of whole blood.
During blood component preparation :
• 90% of leukocytes fractionate with the red
blood cells (RBCs).
• 8% is retained within Platelet concentrates.
• 2% are present in the plasma before
freezing.
Leukocyte reduction can be achieved by
various techniques, including :
 Centrifugation
 Leukocyte filtration
 Sedimentation
 Washing
 Freeze-thawing
 Apheresis
Leukocyte Reduction Filters
Generation
Pore Size
Mechanism
First
170–260 um
Screen filter
Purpose
No leukocyte filtration;
“standard” blood filter
Micro-aggregate filter;
Second
20–49 um
Screen filter
leukocyte filtration,
90%
Adsorption filter;
Third
Not applicable
Adhesion filter
leukocyte filtration
99.9%
Leukocyte
Filters
Adverse Effects Associated
with Donor Leukocytes
Nonhemolytic febrile transfusion reactions
Transmission of leukocyte-associated viruses
cytomegalovirus
3. Alloimmunization
4. Immunomodulatory effects
5. Cancer recurrence
6. Postoperative infections
7. Transfusion storage time for red blood cells
8. Transfusion storage time for platelets
9. Transfusion-related acute lung injury
10. Transfusion-associated graft-versus-host disease
1.
2.
1. Febrile Nonhemolytic
Transfusion Reactions
Definition : as a temperature increase of 1°C
after an allogeneic blood transfusion.
Cause : alloantibodies in the recipient’s
plasma against antigens present on donor
leukocytes and/or platelets
Incidence:
0.5% in patients receiving a first transfusion
60% in Chronically transfused patients
2. Transmission of leukocyteassociated viruses
(e.g.cytomegalovirus)
 Transfusion-associated
CMV
infection
is
a
significant cause of morbidity and mortality in
immuno-compromised patients and especially in
organ transplant recipients.
 After either kidney or liver transplants, more
than 60% of patients develop antibodies against
CMV.
3. Platelet Refractoriness
and Alloimmunization
 Alloimmunization can reduce the clinical
effectiveness of platelet transfusions by
50%. Especially prevalent among those :
- Patients receiving pooled random donor
platelet concentrates.
- Who are Pregnant.
4. Immunomodulation and
Postoperative Infectious Complications
Contaminating leukocytes in RBC transfusions
might be responsible for down-regulation of :
 Natural-killer (NK) cell activity,
 T cell proliferation
 T lymphocyte antitumor activity
 CD-4 helper to CD-8 suppressor ratio
 Lymphocyte blastogenesis
5. Cancer Recurrence
 An
association between allogeneic blood
transfusion and colorectal cancer recurrence after
surgery.
 Blood transfusions in colorectal surgery patients
have been reported to increase cancer recurrence
by 37%also have been associated with increased
recurrence of breast, lung, kidney, prostate,
stomach, cervical, laryngeal, soft tissue, and bone
malignancies.
6. Postoperative infections
 Transfusion
of
blood
components
containing bacteria may lead to potentially
fatal sepsis.
 Cause : inadequate skin preparation
before venipuncture.
 Common pathogens : include Gramnegative endotoxin producing organisms
such
as
Yersinia
enterocolitica,
pseudomonas and enterobacter
6. Postoperative infections
Optimal storage time before filtration to
allow for maximal leukocyte ingestion of
bacteria appeared to be between 2 and 12
hours.
 The beneficial effect of leukocyte reduction
may lie in removal of leukocytes containing
ingested bacteria.

7. Transfusion storage
time for red blood cells
 Decrease ATP.
 Glucose consumption.
 Increase lactate and k+ production.
 The presence of leukocytes in blood
components reduces glucose availability.
 leukocyte lysis leads to release of
cytokines that reduce RBC survival.
8. Transfusion storage
time for platelets
 Decreases in pH
 Increases in glucose consumption
 Lactate production
 Lactic dehydrogenase release
 Platelets stored with leukocytes express
decreased quantities of glycoprotein Ib
(GPIb) receptor, resulting in a bleeding
disorders.
9. Transfusion-related
acute lung injury
 Stored
blood contains micro-aggregates
degenerated leukocytes, platelets and fibrin
of
 These micro-aggregates have been associated
with
pulmonary
insufficiency
due
to
agglutination of donor leukocytes by recipient
antibodies.
 C/P
: severe dyspnea,
pulmonary edema.
non-cardiogenic
10. Transfusion-associated graftversus-host disease (GVHD)
GVHD is a potentially lethal condition.
Cause : donor T lymphocytes.
Mechanism : immunocompromised recipients, host defense
mechanisms fail to suppress viable transfused donor
lymphocytes, which engraft within the recipient’s marrow,
ultimately resulting in death.
Occurrence :
1. when the donor and recipient share an HLA haplotype.
2. Use of directed-donor blood from first degree relatives.
Prophylaxis : gamma-irradiation.
Adverse Effects of
Leukocyte Reduction
Few side effects have been reported
1. Hypotension : due to release of bradykinin like
vasoactive substance esp. in patients receiving
ACEI
prolong intravascular half life of
bradykinin : by decreasing bradykinin
degradation.
2. Complement activation and formation of
platelets aggregate
2%-8% decrease in potency of cellular
components of blood.
3. Red eye syndrome ( allergic conjunctivitis).
- Erythema 100%.
- Periorbital edema 16%
- Eye pain 15%
- Itching
Symptoms resolve 48 hours but erythema may
require up to 3 weeks.