Blood Bank Immunology Principles & Application

Question 1

Immunology as it relates to Blood Banking

Answer 1

involves the immune response to transfusion of cellular elements containing antigens and/or antibodies

Question 2

Immunohematology

Answer 2

the study of blood group antigens and antibodies

Question 3

Blood Banking

Answer 3

originally referred to as the storage of blood and blood products for later transfusion

Question 4

Transfusion Medicine

Answer 4

medical field that deals with the transfusion of blood and blood products

Question 5

Innate Immunity Overview

Answer 5

includes phagocytic cells, chemical mediators, and promotion of the inflammatory system
NO MEMORY

Question 6

Physiologic responses leading to inflammation

Answer 6

vasodilation: increased blood flow & increased temp
edema: increased capillary permeability w/ an increase in fluid
phagocyte migration into tissue

Question 7

Symptoms following transfusion

Answer 7

most common - raised, red, itchy skin rash (urticaria)
swelling of hands, feet, arms, etc
dizziness
headaches

Question 8

Acquired immunity overview

Answer 8

specific immune response w/ memory involving antibodies and complement etc

Question 9

immunogen

Answer 9

any antigen that causes a detectable immune response

Question 10

epitope

Answer 10

part of an antigen that is recognized and bound by specific antibody

Question 11

haptens

Answer 11

low molecular weight molecules that are only antigenic when combined with a carrier

Question 12

relative antigenicity

Answer 12

proteins > CHO > lipids /DNA
glycoproteins > CHO
lipoproteins > glycolipies > lipids

Question 13

Immunogenicity

Answer 13

more foreign 
3D structures
over 10,000 daltons
greater the dose
intravenous > other routes of administration

Question 14

Red Cell antigens

Answer 14

over 250

proteins (RhD), CHO (A,B) or glycolipids (P family)

Question 15

Platelet Antigens

Answer 15

90% of platelet antibodies are to HLA proteins on the surface of platelets
10% are to platelet proteins
can cause post transfusion purpura in which the platelets are destroyed following transfusion

Question 16

Relevance of IgG antibodies

Answer 16

IgG can cross the placenta! & can cause destruction of fetal RBC in HDNB

Question 17

Anamnestic Response

Answer 17

also called the secondary immune response - the characteristic short lag phase that occurs within 1-2 days of exposure
bc of memory cells from primary exposure, the concentration of circulating antibody is much higher (IgGs)

Question 18

RBC antibody production

Answer 18

depends on : 
person must lack the antigen
immunocompetence 
survival of antigen in circulation
antigenicity of the antigen
number of antigenic exposures

Question 19

‘Naturally Occuring Antibodies’

Answer 19

present in people not sensitized by RBC antigen exposure

produced by environmental substances that contain antigens similar to RBC antigens

Question 20

Immune-Stimulated Antibodies

Answer 20

produced in response to exposure to specific RBC antigens through TRANSFUSION or PREGNANCY
most are IgG
most common are Rh, Kell, Duffy, Kidd, and Ss

Question 21

Affinity

Answer 21

the binding between a single antibody and epitope of an antigen

Question 22

affinity is effected by

Answer 22

goodness of fit (size & shape)

strength of molecular forces leading to binding

Question 23

avidity

Answer 23

overall strength of reactions between antigen-antibody complexes

Question 24

avidity is effected by

Answer 24

valency of antibody

affinity

Question 25

Antigen-antibody reactions

Answer 25

high Ag & Ab drives reaction forward (form complexes) low Ag & Ab drives the reverse reaction when Ab is IgG - at 37 AgAb complexes are favored when Ab is IgM - at 25 AgAb complexes are formed

Question 26

hemagglutination

Answer 26

agglutination of RBCs to form a visible clump antibodies bind to antigens on RBC surface 0, +/-, 1+,2+,3+.4+

Question 27

RBC hemolysis

Answer 27

occurs when complement is activated, membrane is damaged, intracellular fluid is released & supernatant becomes red

Question 28

Sensitization phase

Answer 28

``` first stage of in vitro antibody antigen binding usually not visible influenced by : cell: serum ratio temp incubation time pH & ionic strength ```

Question 29

Effect of Temperature

Answer 29

cold antibody vs warm antibody

Question 30

effect of pH

Answer 30

6.5-7.5 is usually best some antibodies (anti-M) react better in more acidic pH

Question 31

effect of Incubation time

Answer 31

longer time enhances lattice formation

Question 32

effect of ionic strength of medium

Answer 32

reducing ionic strength by using LISS will enhance some antigen-antibody reactions

Question 33

second stage of agglutination

Answer 33

formation of aggregated RBCs or lattice formation that are visible important factors : immunoglobulin class # of antigen sites on RBCs location & proximity of antigen sites on RBC zeta potential

Question 34

Zeta Potential

Answer 34

force of repulsion between RBCs in a normal saline suspension RBC have - charge & + cations form an ion cloud around RBC preventing 2 RBCs from getting close enough to agglutinate LOWER zeta potential = better

Question 35

Enhancing Agglutination in vitro

Answer 35

physical methods & enhancement media/ potentiators

Question 36

physical methods of enhancing agglutination

Answer 36

centrifugation temperature pH AHG

Question 37

Potentiators for enhancing agglutination

Answer 37

PEG LISS Albumin Enzymes

Question 38

Anti-Human Globulin(AHG)

Answer 38

anti-human antibodies bind to sensitizing globulin antibodies and form bridges between antibody coated red cells resulting in visible agglutination strength of reaction is proportional to the amount of globulin coating the RBC

Question 39

DAT: direct antiglobulin testing

Answer 39

looks for antibody bound 'in vivo' for hemolytic immune diseases looks for anti-IgG & anti C3b/d

Question 40

IAT: indirect anti-globulin testing

Answer 40

looks for antibody bound 'in vitro' - detect IgG bound to RBC in vitro read for agglutination

Question 41

Antibody Detection

Answer 41

uses screening cells to detect antibodies w/ specificity to RBC antigens

Question 42

Antibody ID

Answer 42

IDs specific RBC antibodies

Question 43

Crossmatch

Answer 43

determines serologic compatibility between donor and patient

Question 44

Antigen typing

Answer 44

IDs specific RBC antigen in patient or donor

Question 45

sources of false positive results

Answer 45

contaminated specimen or inappropriate specimen over-reading spontaneous agglutination sample storage can be caught through the use of an autocontrol

Question 46

sources of false negative results

Answer 46

``` failure to adequately wash cells delay in reading under reading excessive shaking of tube inoptimal temperature can be caught through the use of check cells (IgG sensitized RBCs) ```

Question 47

IgG Sensitized cells : Check Cell

Answer 47

ensures all negative AHG tests that in fact AHG was added, cells were washed sufficiently, & AHG would be able to react CHECK CELLS SHOULD GIVE A POSITIVE reaction