Blood Bank, test #3, Ab Identification, Fall 09

Antibody Identification

determining the specificity & clinical significance of a previously detected blood group antibody

Why ID Ab's in the plasma of transfusion candidates?

1. decide if its clinically significant 2. provide Ag neg RBCs if needed 3. perform long crossmatch if indicated

Why ID antibodies in the plasma of OB (pregnant) pts?

1. determine if the Ab is IgG 2. predict possibility of hemolytic disease of the newborn 3. be ready if blood needed at delivery

Why ID antibodies in the plasma of blood donors?

1. remove the plasma from component (not used for transfusion) 2. label the component w/ info about the Ab

5 Antigens you can cross out immediately b/c the incidence is so low??

V, VS, C^w, Kp^a, & Js^a

5 blood grp systems we can cross out w/o worrying about dosage (we dont care if cell is homo or hetero for Ags)??

Lewis, Lutheran, Kell, P1, Xg^a

4 systems we only cross out if they are HOMOZYGOUS for that Ag??

MNSs, Rh, Duffy, Kidd

What to look for in patient history??

1. History of transfusion 2. exposure to Ags foreign to pt 3.pregnancy 4. meds (some alter immune response)

Why are Ab panel cells all type O??

you want unexpected Abs to react...... you dont want anti-A or anti-B to react

Why do you have to FINISH testing b4 interpretation?

if you begin to interpret too early, you may cross out an Ag that would react later

what the point of the auto control?

if it reacts-->Ab is probably an AUTOANTIBODY & if it does NOT react-->ALLOANTIBODY


Ab produced by one individual of a species against Ags carried by other individuals in that species

If more than 1 possibility for an Ab left, how do you decide??

Look VERTICALLY for perfect match to rxns

When is Ab clinically significant??

If it reacts at 37C and/or at AGT

Potential problems if Multiple Ab's?

different rxns at different stages, some rxns may be stronger than others

Potential problems in Dosage??

phenomenon where Ab reacts more strongly w/ homozygous cells than w/ heterozygous (sometimes reacts only w/ homozygous)

Potential Problem-->Ab to a high frequency (public) Ag?

All cells react! (or most)

Potential problems w/ Ab to Low frequency (private) Ag??

only one cell reacts (or few)

Potential problem-->Ab to the reagents??

All cells except the AC react............ fix by washing reagent cells THEN add serum

Potential problems??

multiple Ab's, Dosage, Ab to public Ag, Ab to private Ag, Ab to the reagents

Why would you want to TITER an Ab??

HDN case......... semi quantitative test for How Much Ab is in pt sample....... see how dilute the serum can be b4 it STOPS reactign

Whats TITER??

reciprocal of the highest dilution of serum that gives a visible rxn

What's a score?

Assigned point value to each rxn: 4+ = 12, 3+ =10, 2+ +8, 1+ =5, +/- =2, H=10

How to score in Ab TITER?

add up all the scores

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