Antibodies Are Not Always What They Seem. Lindsay Peters MLS(ASCP)SBB Reference Laboratory Supervisor Mississippi Valley Regional Blood Center

Transcription

1 Antibodies Are Not Always What They Seem Lindsay Peters MLS(ASCP)SBB Reference Laboratory Supervisor Mississippi Valley Regional Blood Center

2 Case Study Patient: Mrs. Holmes is admitted to the ICU following a fainting spell. She has a hgb of 6.0 and it is discovered she has internal bleeding due to the fall. Transfused 2 weeks ago after hip replacement Pregnant 4 times over 30 years ago

3 Initial Results Anti-A Anti-B Anti-D Rh Cont A1 Cells B Cells GEL Screen Cell 1 2+ Screen Cell 2 2+ Screen Cell 3 2+ IgG C3b,-d Control

4 Plasma D C c E e K k Fya Fyb Jka Jkb Lea Leb M N S s Gel Auto Control 2+

5 Eluate D C c E e K k Fya Fyb Jka Jkb Lea Leb M N S s Gel

6 Transfusion Reaction?

7 Differentiating AUTO from ALLO in Recently Transfused Patients First step is to obtain a pure sample of patient s RBCs Retic or Sickle Test the patient s cells to see if coated with antibody DAT on Retics Negative with anti-igg

8 Differentiating AUTO from ALLO in Recently Transfused Patients DAT negative Retics Test with plasma Neg- Allo Positve- Auto Test with eluate Neg- Allo Positive- Auto

9 Plasma D C c E e K k Fya Fyb Jka Jkb Lea Leb M N S s Gel Retic Auto Control 0

10 Eluate D C c E e K k Fya Fyb Jka Jkb Lea Leb M N S s Gel Retic Auto Control 0

11 Further Down the Rabbit Hole Now that we have established it is alloantibody present in the plasma and eluate there are more?s Is it one high incidence allo? If so which one? Is it clinically significant? Is it multiple allos?

12 R1R1 Adsorbed Plasma D C c E e K k Fya Fyb Jka Jkb Lea Leb M N S s Gel

13 R2R2 Adsorbed Plasma D C c E e K k Fya Fyb Jka Jkb Lea Leb M N S s Gel

14 rr Adsorbed Plasma D C c E e K k Fya Fyb Jka Jkb Lea Leb M N S s Gel

15 How Does This Help?? The differential adsorption may not have told us what the antibody IS, but it has told us what the antibody ISN T Not multiple common allos Can use the adsorption to rule out Now what Time to start fishing for antibodies to high incidence antigens

16 High incidence Antigens Usually defined as any antigen absent in less that 2% of the population Some common Highs Coa, U, Fy3, k, Kpb, Jsb, Joa, Hy, JMH, Ch/Rg, Sla, Ge, Kn How can we figure out which one? Run a bunch or rare ag neg cells Use the properties of the antigens Treatment with Enzymes/ Chemicals

17 Enzymes Cleave all or part of some antigens leaving them non-reactive with the respective antibody Ficin/ Papain Trypsin Bromelin Pronase Alph-chymotrypsin

18 Chemicals Most commonly used 0.2M DTT (Dithiothreitol)/ 2-ME (mercaptoethanol) Sulfhydryl Compound Breaks disulfide bonds of some antigens Kell Blood Group (K, k, Jsa, Jsb, Kpa, Kpb) Others

19 Enzymes/ Chemicals Since there is information available about how each antigen responds when treated with the different Enzymes/ Chemicals, we can use that information to narrow down the possibilities Most commonly used is Ficin 0.2M DTT

20 Enzymes/ Chemicals Ficin/ Papain 0.2 M DTT Possible Specificty Negative Positive M, N, S, s, Ge2/4, Fya, Fyb, Ch/Rg Negative Negative Indian, JMH Positive Weakened Knops. Lutheran, Dombrock Positive Negative Kell, LW Positive Positive P1, Rh, Lewis, Kidd, Fy3, U, Co, I, Vel, Sda Positive Enhanced Kx

21 Plasma D C c E e K k Fya Fyb Jka Jkb Lea Leb M N S s Gel Ficin DTT

22 Antigens and Race High Incidence Ag Absent Oh (Bombay), Inb Population Indian U, hrs, hrb, Jsb, Fya-b-, Fy3, Hy, Joa, Sla Black JK3 Polynesian k, Kpb, Kna White Dib Yta Jra South American Arab/ Jewish Japanese

23 Only a Few Remain Most likely based on Race hrs, hrb, Fy3, U hrs/ hrb- look like anti-e Fy3- RARE specificity for Aby because of GATA Could also be Vel, Sda, Co, Lea/b Vel- Should be greatly enhanced by enzyme Sda- Usually IgM, agglutinates usually small and refractile in a sea of free RBCs

24 Time to Get Out the Big Guns Now its time to find some rare cells to run

25 Rare Cells D C c E e K Fya Fyb Jka Jkb Lea Leb M N S s Gel Eluate Fy Lea-b U U Coa

26 U Antibody Part of the MNS Group Present in 99.9% of the population S-s- 99% in the Black population 80% U- 20% U+ U variant- weaker U expression, not all the same