Patient, 57 year old male presenting with SOB due to chronic anemia. Crit of 21% Last transfusion was in 2000 and he received six units for a GI bleed. History of a non specific cold auto- agglutinin in 1999 and 2000. "don'Tcheat......Try and decide how you would proceed!

Current reactions: Front types as an A pos (R1R1), Back types as a group O.

Gel - all cells are 4+ and auto control is negative, Liss panel demonstrates

some reativity at IS, all cells are 3+ at 37'C and 3-4+ at IgG.

Peg---All cells are 4+ and auto control is neg

Ficin treated cells are 3+ at 37'C and 4+ at IgG, Auto control is 2+ at 37'C

and 1+ at IgG

DAT.....AHg (neg), IgG (neg) C3b, C3d(neg)

Cold panel......(three O cells, Cord, I neg adult, Auto and A1, A2, B cells)

All cells except auto are 3+ at R.T., 4+ at 18'C and 1-2+ at 4'C

auto is neg until 4'C then it reacts only 1+

ok............put your thinking caps on........what would you do next???????

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Well, I tried VEL neg, Bombay, Para-bombay and they all reacted !!!!!! REST absorbtion was a waste of time..... it weakened it by about one degree.

I phenotyped the patient and ran matching cells, they all reacted the same.

I then took and performed a differential absorption to rule out all "common" allo-antibodies.

It took five passes, four at 37'C and one at 4'C.

There were no commom allo antibodies present.

________________________________________ok!!!!! So we know it must be a high freq, but which ones would like IS,37; and IgG? and remember the patient has not been transfused in four years?

Ok...throw out some ideas......Please respond and I'll tell you what it is and how I finally figured it out!

You know Melanie, you make me happy that the tough ones we send out. We can do Differential absorptions (but rarely).

So what is your answer?

So, Now I had already DTT treated some cells the day before and thought, what the heck, I'll give it a try,,, can't hurt? The three DTT treated cells were negative!

AHHHHHHHHHHHH HAAAAAAAAA!

What is destroyed by DTT? You guessed it..... the K system!

I then typed the patient for Kpa, Kpb, Jsa, Jsb and k. The patient was Kpb neg.....

Who would have thought this???? Not me.

To confirm this, I thawed out some Kpb neg cells and ran them in Liss and Peg and ruled out all other common allo's . :mrgreen:

I would not have thought of that one. Very Rare.