bloodbank exam 3 LSU resource

Lewis

Plasma antigens that adsorb onto RBCs, not alleles

not present on cord cells therefore does not cause HDN. Antibodies: IgM (can be hemolytic), usually only seen in Le(a-b-) persons, often seen in pregnant women who may temporarily become (a-b-)

I, i

I is absent/ weak on cord cells

i converts to I as an infant matures due to branching of carbohydrate chains (not alleles)

infants are i postive, I negative. Adults are I positive, i negative

antibodies: anti- I, IgM cold antibody. reacts with all adult cells except for rare i in adult. may mask clinically significant alloantibody. Remove anti-I to detect underlying antibodies by autoadsorption, RESt, or prewarming serum and using IgG AHD instead of polyspecific

P

P1 antigen strength deteriorates upon storage

antibodies: IgM cold antibody,

Anti-P1 can be neutralized to reveal other clinically significant alloantibodies

Anti-P frequently the specificity of the biphasic Donath-Landsteiner antibody found in Paroxysmal Cold Hemoglobinuria, Reacts with all P or P1 cells

MNSs

M and N are codominant alleles

Antibodies: Anti-M and Anti-N

usually cold IgM, no HDN. Often show dosage (property whereby antibody reacts strongest with cells having a homozygous expression of antigen as opposed to heterozygous

Will NOT react with enzyme-treated cells (M and N antigens are destroyed by enzyme)

Anti-M: many examples are IgG and can cause HDN, may require acidification of serum to identify

Anti-S, anti-s: IgG (warm, can cross placenta)

Anti- U: IgG formed by black individuals who lack S, s, and U

Kell

K and k (cellano) are codominant alleles

K antigen is second most immunogenic (next to D), 91% of people are K negative, antigens inactivated with 2-ME, DTT, or AET

Antibodies: IgG

Kidd

Jk a and Jk b are codominant alleles

Antibodies: IgG, react STRONGER with enzyme treated cells, titers rise and fall rapidly, associated with delayed transfusion reactions

Duffy

Fy a and Fy b are codominant alleles

68% African Americans are Fy(a-b-), antigens are destroyed by enzymes, Antigen typing - Fy(a+b-) : white population homozygous for Fya (FyaFya), black population usually heterozygous for Fya (FyaFy-)

Antibodies: IgG, weak examples may show dosage, negative reaction with enzyme treated cells

Paternity Testing

Maternity is assumed, You may have problems that include ABO and/or D grouping, In paternity testing, there is a legal chain of custody, Molecular testing is starting to replace serological testing

Direct / Indirect testing

RBC blood groups with codominant alleles can be used for parental testing along with HLA systems and DNA analysis, Maternity is assumed,

Direct exclusion- marker present in child, absent from father and mother

Indirect exclusion- child lacks a marker that the alleged father must transmit

Screening Cells and Panels

Commercially prepared group O red cells with specific distribution of blood group antigens (screening cells contain 2-3 different cells: panels vary from approximately 10-20 cells)

Patient serum

added to the cells

Serum-cell mixture is tested at various temperatures, with different enhancement media, and with antiglobulin reagent (IAT)

Patient serum may also be tested against his own cells (autocontrol) to determine the presence of an autoantibody

Indirect antiglobulin test

antibody attached to corresponding antigen on red cells at 37C

excess serum/ antibody removed by saline washes

antiglobulin is added and will bind to antibody on the cells

Positive reaction is indicated by agglutination

IgG sensitized check cells are added, and should have a positive reaction

Enzymes

Ficin, Papain, Trypsin, Bromelin

used to compare with panel results of untreated cellsPan

Panel results

Compare enzyme- treated and untreated cells

If autocontrol is positive, may indicate a delayed transfusion reaction: if positive along with all panel cells, autoantibody may be indicated

enzyme enhanced cells

Kidd, I, P1, Lewis and some Rh (not D)E

Enzyme destroyed cells

Duffy, M, N, S

Dosage

Rh (other than D), M, N, S, Kidd and Duffy

Prewarming technique

After proving no clinically significant antibodies are also present, eliminate reactions due to cold antibodies

warm serum and cells separately to 37 before mixing together, wash with warm saline prior to further testing

Albumin/ Bovine

net negative surface charge, only increase antibody uptake if under low ionic conditions, Rh antibodies may show at 37 C

Low Ionic Strength Saline (LISS)

Increased antibody uptake which allows decrease in incubation time

Enzymes (BFPT)

Removes sialic acid which decreases negative surface charge and promotes cell agglutination, increases reactivity of Rh, Kidd and Lewis antibodies, usually increases warm and cold autoantibodies, destroys M, N, S, Fya and Fyb

Polyethylene glycol (PEG)

increased antibody uptake

removes water which increases antibody concentration which promotes antibody uptake

Kidds and Duffy the Rh Monkey eat lots of M&Ns

Kidds (Jk), Duffy (Fy) and Rh Monkey (C, c, E, e) destroy anti M, N, S, s