We have a 28 yr old female African American patient who reacted with all red cell samples tested, except for Fy(a-b-) cells. Auto controls were only positive with GEL and saline.

DAT + W/AHG,IgG. Eluate was negative.

Her reactivity was weaken by ficin. Original thought was anti-Fy3 and not Fya and Fyb since anti-Fya and Fyb would be destroyed by ficin. This patient has a typical Black type Ro K-Fya-Fyb-Jkb-S-.

We're sending the sample out for genotyping. If she has GATA mutation, she can still make anti-Fy3 and anti-Fya. It's extremely rare for a Black patient to make anti-Fy3. It's usually mistaken for anti-Sl^a.

We decided to perform testing against DTT treatment of red cells and checked against the patient's serum-

Result was negative. This information tells us it might be something in the Knops system. We are still validating trypsin so can't test that. Sl^a would be sensitive to Trypsin while anti-Fy3 is resistant.

Are we heading in the right direction? What are your thoughts?

The fact that the patient has the GATA mutation will not say that the patient can not make anti Fy3, we have had several samples of anti Fy3 in patients from Africa.

But the weakening with ficin and the negative reactions with DTT, and the negative eluate, point more to anti Sla, I would go for that.

Peter

I agree with both of Peter's points.

We've had three cases of anti-Fy3 in patients homozygous for the GATA-1 gene.

Thank-you both Rh-fan and Malcolm. This is why I am active on this site, to get inputs from experts like you:)

Can anyone tell me what the - sign (ex. Scianna -1, -2 or -3) in antigen system means? thanks

The "-"sign means that that antigen is absent.

Sc-1,2 means Sc1 negative anti Sc 2 positive. In this case there is no information about the Sc3 antigen.

Sc-1,-2,-3 means that Sc1, Sc2 and Sc3 are negative.

Thank you

One more question,

Our Fy(a-b-) cells came up with ficin. That's odd. Fy3 is resistant to ficin but it should not come up if it's not there to begin with. Any thoughts.

One another subject, if you have a typical WAA but is reacting at IS and 37 and RT and 4C, do you call it WAA broad thermal amplitude or mix of cold and warm?

Do you report of cold antibody based on 4C testing only? AKA, no other reactions at IS or RT.

Do you report of cold antibody based on 4C testing only? AKA, no other reactions at IS or RT.

4C is not a good temp to test, almost anybody has antibodies at that temp. So it will not give enough information.

16C to RT is a better temp. Antibodies that are reactive at that temp have a link to something clinical in the patient (mostly a kind of infection) and can couse problems in your antibody testing, becouse you put your serum and cells together at that temp (cold antibodies could bind and stay even when you incubata at 37C).

Cold antibodies that are reactive at 30C can couse red cell destruction in vivo.

One more question,

Our Fy(a-b-) cells came up with ficin. That's odd. Fy3 is resistant to ficin but it should not come up if it's not there to begin with. Any thoughts.

One another subject, if you have a typical WAA but is reacting at IS and 37 and RT and 4C, do you call it WAA broad thermal amplitude or mix of cold and warm?

a test with ficin treated cells is always stronger than with normal cells (when the antigen is not destructed). The expression of FY (and Kell) antigens is not realy enhanced but antibodies to these antigens (for Fy only 3 and 5) can be detectable with ficin treated cells when untreated cells are not. For Rh, Jk and Le it is alsways much stronger but for te other it can also be a little bit.

The problem with multiple temp amplitudes is that you have to be sure that you are testing only one temp at a time. So pre-warm or pre-coling is needed, and even centrifugation at that temp. I fit is stil that case we say there is a mix of cold and warm

I agree with Peter that mixed-type autoimmune haemolytic anaemia is one of the hardest to prove unless you perform all the testing required.

I would cite Mayer B, Yurek S, Kiesewetter H, Salama A. Mixed-type autoimmune hemolytic anemia: differential diagnosis and a critical review of reported cases. Transfusion 2008; 48: 229-2234, as an excellent paper to read to see what is required in the way of testing to prove this condition.

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