Bloodbank Reagents

hemagglutination

aggregation of particulate caused by a combination with a specific antibody

what are the two stages of agglutination

sensitization: antigen binds with antibody

lattice formation: aggregates develop (clumping)

what is the preferred sample used for blood bank testing

EDTA plasma (pink or lavender top)

why is EDTA plasma (pink/lavender top) the preferred sample for bloodbank

this tube lack the fibrin strands that cause false positives in the direct antibody test (DAT) and elution tests

prozone

too much antibody in relation to antigen

too little saline

equivalence

optimum amount of antibody to antigen

postzone

too mich antigen in relation to antibody

too much saline

what are the types of antibody reaction phases

immediate spin phase (cold, IgM) and antiglobulin phase (warm, IgG)

zeta potential

the salic acid that creates a negative charge between two RBCs so they don’t stick

how do IgG and IgM fcator into zeta potential

IgM is bigger so it gets stuck/can bind between the RBCs

IgG needs reagent so the RBCs become closer together so it can get stuck/bind to the RBC

4+ agglutination

one solid aggregate cell button, clear background

3+ agglutination

several large agglutinates, clear background

2+ agglutination

several medium-sized agglutinates, clear background

1+ agglutination

many small and medium sized aggluntinates, turbid background

+^w agglutination

many small but barely visible clumps, turbid background

0 agglutination

no visible agglutinates, turbid background

H agglutination

hemolysis, pinky-red background that looks like dye in water

where are antibodies found in patient specimen

patient plasma/serum

where is antigen found in patient specimen

on patient RBCs

non-traditional methods used in bloodbank

fluorescence-assisted cell sorting (FACS)

• compound absorbs light energy of one wavelength and emits light of a different wavelength

flow cytometry

• antibody is tagged with fluorescent dye (has direct and indirect)

what reagents are used for ABO antigen typing

(antisera) anti-A and anti-B (forward typing)

what reagents are used for Rh typing

anti-D (and patient cell suspension)

what reagents are used for screen cells

reagent screen cells I, II, and III (and patient plasma)

what reagents do panel cells use

reagent panel cells (and patient plasma)

how are reagent red cells used for serum testing

they are prepared for human donors (washed and suspended in 3-5% concentration

what does AHG stand for

antihuman globulins

what is AHG used for

enhancing immunoglobulin activity after a 37 degrees celsius incubation and washing stage

what are the two major types of antibodies AHG is used to detect

monoclonal and polyclonal antibodies (IgM and IgG)

what does DAT stand for

direct antibody testing

what does IAT stand for

indirect antibody testing

why is a DAT test preformed

to determine in vivo (in the body) sensitization of RBCs with IgG or complement components

is DAT or IAT required in pretransfusion testing

only IAT

what can cause sensitization of RBCs in vivo with the DAT test

hemolytic disease of the fetus and newborn

hemolytic trasnfusion reaction

autoimmune induced hemolytic anemia

drug-related hemolytic anemia

what does sensitization of RBCs mean

occurs when the body produces antibodies to attack foreign antigens on the RBCs

can occur when the body encounters a new blood type

DAT is also known as

direct coomb’s test

preferred sample for testing for DAT

EDTA to prevent complement from attaching non-specifically in vitro (in the tube)

DAT procedure

wash the RBCs to remove unbound antibody

polyspecific AHG is added and then centrifuged so the anti-IgG or anti-C3d will bind to the antibody or complement attached to the RBC

DAT involves what

RBCs and AHG

DAT is a one stage test, what does that mean

you don’t have to incubate it, you just wash and add AHG then centrifuge

IAT is also known as

indirect coomb’s test

antibody screening

why is IAT done

to detect in vitro (in a tube) sensitization of RBCs with antibody

procedure for IAT

antibody and RBC are incubated to allow attachment of antibody to corresponding antigen

RBCs are washed to remove any unbound antibody

AHG is added then the specimen is centrifuged so that anti-IgG binds to antibody bound to RBC causing agglutination

IAT involves what

RBCs and IgG

IAT is a two stage procedure, what does that mean

there is a incubation period, then washing, then centrifuging

polyspecific antibody contains

antibody to human IgG AND complement anti-C3d (maybe some anti-C3d)

monospecific antibodies contain

monospecific IgG contains either anti-IgG OR anti-complement (C3d, -C3b)

monospecific anticomplement contains anti-C3b, C3d which is reactive only with designated complement ocmponents

advantages of polyspecific

capable of detecting mnay different IgG varients

increased hyperimmunized to produce higher titer and avidity to IgG

polyspecific AHG perferred when preforming DAT

cheap

disadvantage of polyspecific

has the inabbility to determine potency of anti C3b, C3d individually

advantages of monospecific

can determine potency of anti C3b and C3d individually

it’s a higher titer antibody with well defined specificty to IgG + C3

identical in antibody structure and antigen specificity

pure uncontaminated AHG reagent

disadvantages to monospecific

only recognizeds a single epitope present on an antigen

more expensive

purpose of check cells

verifies that the wash stage was sufficient and that the AHG was added

check cells are also known as

coomb’s control cells

check cells should always be _________________

positive

check cells should only be used when AHG is ____________

negative

fcators that affect AHG testing

serum to cell ratio

reaction medium (albumin, PEG, LISS)

temeprature

incubation time

washing of RBCs

saline quality

addition of AHG immediately after washing

correct centrifugation

what different technology is used (other than a tube) for AHG

low ionic polybrene technique

enzyme-linked immunosorbent assays (ELISA)

flow cytometry

solid phase

gel test

purpose of lectin and source of it

seed extracts that have a specificity toward red cell antigens

they react like antibodies (IgM) and are used as antisera for antigen typing red cells, useful in ID-ing certain types of blood group antigens on patient or donor RBCs

what entitiy is responsible for blood bank reagents

liscensed by the FDA

which immunoglobulins react at room temp

IgM

which immunoglobulin react at body temp

IgG

what does SOP stand for

standard operating procedures

the reagent used for Rh typing (anti-D) is divided into two categories, what are they

high protein anti-D and low protein anti-D

high protein anti-D consist of

polyclonal antibodies in diluent

does high protein anti-D need an Rh control

yes, if that control is positive you can’t use D-typing

low protein anti-D consist of

monoclonal or monoclonal/polyclonal blend

does low protein anti-D require Rh control

no