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Warm free auto antibody with weak auto control


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We have a female patient- group O R1r  (56) who has a high titre antibody. Still 2+ at 1/1024. The reaction by Gel IAT v neat plasma is 4+ with all cells apart from the pvp which is 3+.  By LISS tube IAT the reactions are 3+ v the screening cells but the pvp is markedly weaker. The differential IAT shows an IgG coating only. The allo absorbed plasma  was completely negative v panel by Gel IAT.  A RT direct tube screen gave 2+ reactions with all cellsincluding the pvp and Oi . I am concerend that there may also be an antibody to a high incidence antigen present and would appreciate any thoughts.

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1 hour ago, catm said:

The differential IAT shows an IgG coating only. The allo absorbed plasma  was completely negative v panel by Gel IAT.  A RT direct tube screen gave 2+ reactions with all cells including the pvp and Oi .

I presume by the first sentence above that you mean only IgG is on the patient's cells; no complement ?

I'm impressed that you could remove such potent, HTLA-ish antibody by allo-adsorption. How many adsorptions were needed? Did you use enzymes ? Is the RT direct tube test against the adsorbed serum or unadulterated ?

Do the patient's cells autoagglutinate, i.e., do they react in just saline or an albumin solution, either by RT or IAT ?

If the patient is currently untransfused, you could try autoadsorption. You may need to use ZZAP/WARM to treat the cells.

You can also try to make the DAT negative with Chloroquine or an acid elution. Testing DAT-negative cells back against the serum will allow you to confirm that there is an autoantibody present. 

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I am afraid that I am not totally convinced that what you have here is a "warm" auto-antibody.  I just wonder if, what you have is either a "cold" auto-antibody of wide thermal amplitude or, possibly, but seen less commonly, a case of a mixed "warm" and "cold" auto-antibody, however, having said that, I am not certain, from what you have written, whether or not the direct tube testing at room temperature was performed on allo-adsorbed plasma or "neat" unadsorbed plasma.  Please would you clarify this?  Please would you also try to tell us the patient's underlying pathology?

I would not worry too much about the patient's autologous red cells give slightly weaker reactions than those seen with panel cells or screening cells.  The autologous red cells will have been "bathed" in the high titre antibody in vivo, whereas the other red cells are, if you like, "meeting the antibody for the first time"!  It is likely, therefore, that there is a certain amount of "antigen blocking" going on with the autologous red cells.

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Thanks for your responses and suggestions.

In answer to your questions. The cells appear to auto agglutinate using CAT - all wells positive in ABO and Rh cards but typing by tube was fine- no false positive reactions.

We used NHSBT adsorption cells which are enzyme treated. We did the adsorption 6 times.

We do not have access to chloroquine so can't try removing the auto antibody.

 

The direct testing at RT was done with the neat unadsorbed plasma. The only information I have about the patient is that they have macrocytic anaemia.

 

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Thank you for the further information catm.  It has strengthened my feeling that what you have here is actually a "cold" autoantibody of wide thermal amplitude, despite the fact that the DAT appears to be positive with an anti-IgG, rather than anti-C3d.  Although most "cold-reacting" autoantibodies tend to be IgM, it must not be forgotten that some are IgG (as are some cold-reacting alloantibodies, such as ABO antibodies, anti-M, etc, and the classic DL autoantibody, anti-P), however, this could also point to a mixed "cold" and "warm" autoimmune haemolytic anaemia.  In addition, it could well be that the lady has no free complement in her system, because of consumption.

The ABO and Rh results in CAT are classic for cold agglutinin.

Again, the reactions at room temperature, performed on neat, unadsorbed plasma are classic, as is the macrocytic anaemia and the very high antibody titre.

May I suggest that, if you can, you treat the patient's plasma with dithiothritol, to see what happens, particularly in CAT?

Could I also suggest that the plasma is tested at strict 30oC?

Your comment, "We use NHSBT Adsorption cells..." suggests to me that you are not a Reference Laboratory (I am quite prepared to be slapped down if I am wrong!) and, if I am correct, I would strongly suggest that a sample is sent to a Reference Laboratory.

Lastly, may I ask that you keep us informed about this patient?

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  • 2 weeks later...

Just to update you on the outcome of this case. We tested the plasma against  Null cells by IAT and it was negative with an Rh null cell. We sent it for further testing.Our results were reproducible but they got a strong positive result with the enzyme auto (which we don't do) and concluded it was an auto antibody with Rh specificity. 

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11 minutes ago, catm said:

Just to update you on the outcome of this case. We tested the plasma against  Null cells by IAT and it was negative with an Rh null cell. We sent it for further testing.Our results were reproducible but they got a strong positive result with the enzyme auto (which we don't do) and concluded it was an auto antibody with Rh specificity. 

Thank you very much indeed for that catm.

I am happy that there was an Rh antibody (or Rh antibody-like antibody) there (which doesn't surprise me in the least), but the fact that there is a reaction with enzyme auto does NOT rule out a mixed warm and cold AIHA - if anything, it strengthens my suspicion.

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