Autoimmunity Against Red Cells

RCI Investigations - Autoimmunity Against Red Cells

 

ABO and full Rh phenotype

ABO and full Rh phenotype are performed on all patients. Patients who have received recent multiple transfusions may be genotyped for the same antigens by RCI. 

The direct antiglobulin test

The direct antiglobulin test is performed with broad spectrum anti-globulin reagents and class specific reagents [anti-IgG, -IgM, -IgA, -C3d,-C3c]. 

Serological Investigation

Investigations include the detection and identification of allo-antibodies which might be masked by auto-antibody. If free auto-antibody is present auto- or allo-absorptions or titrations are used, depending on the circumstances, to reveal clinically significant allo-antibodies. Eluates are normally prepared and tested only if the patient has been recently transfused or has received haemopoietic stem cell or bone marrow transplant.

Transfusion advice

It is recommended that patients with autoantibodies reactive at 37°C are transfused with ABO compatible units which are antigen negative for any clinically significant allo-antibody present. Units should be K negative and of an Rh phenotype compatible with that of the patient, to prevent the formation of Rh and K alloantibodies. If haemolysis is very severe, blood compatible with an apparent specificity of the autoantibody could be transfused but clinical advice should be sought. Transfusion advice is given on a case by case basis and blood can be cross-matched by the reference laboratory if required.

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Drug associated auto-immune haemolytic anaemia

Haemolysis suspected to be associated with drug treatment can be investigated, but advice should be sought from the scientific or consultant staff at your local blood centre before sending samples.

Transfusion advice

Advice should be sought from the scientific or consultant staff in the NBS Red Cell Immunohaematology Department.

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Cold agglutinins/haemolysins and chronic haemagglutinin disease

A DAT is performed and the plasma is investigated for the presence of clinically significant red cell alloantibodies strictly at 37°C.  It is not necessary to warm separate samples unless titration studies are required or specifically requested to do so by the NHSBT laboratory.  Cold agglutinin titrations can be performed on request in Cold Haemagglutinin Disease patients.

Transfusion advice

SAGM-suspended cells that are ABO compatible, K negative and of a Rh phenotype matched with that of the patient are selected for transfusion. If the patient has clinically significant red cell antibodies units must also be negative for the relevant antigen(s).  The blood is crossmatched by a standard antiglobulin technique strictly at 37°C.  It is advised that units are transfused through a blood warmer

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Biphasic haemolysins and paroxysmal cold haemoglobinuria

Biphasic haemolysins as a cause of AIHA are extremely rare and mainly seen as a post-viral event in children. Routine investigations do not include the test for biphasic haemolysins, but where indicated, or on request the Donath-Landsteiner test can be performed if paroxysmal cold haemoglobinuria (PCH) is suspected. If positive the specificity of the antibody can be determined, to confirm the diagnosis.

Transfusion advice

The haemolysis in PCH is generally self-limiting. Transfusion requirements can be discussed on a case by case basis with an NBS Consultant.

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Paroxysmal nocturnal haemoglobinuria

If you require investigation of a suspected case of PNH the NHBTS laboratories will refer you to as specialist centre such as

  • Haematology Malignancy Diagnosis Service at Leeds Teaching Hospitals. Tel 0113 392 6285.
  • Hospitals may refer samples there directly for testing. 
  • Birmingham Heartlands: 0121 424 0706 Haematology dept King’s College Hospital, London 0203 299 3520

Transfusion advice

Previously washed red cells were recommended for PNH patients.  However, there is no evidence that the survival of washed red cells is better than that of those suspended in SAG-M. 

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