Case Study Review

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Case Study Review

• Warm Autoantibody Identification

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Warm Auto-Antibody Study

• An 83 year old female comes into the emergency
  room complaining of fatigue and shortness of
  breath. Her medical history indicates that the
  patient has been receiving blood due to anemia
  for the last six months. Her last transfusion
  was two months prior to this admission. Blood is
  drawn and testing reveals that her current
  hemoglobin is 8.4 g/dL. She now has a positive
  antibody screen. Samples are collected and
  forwarded to the Reference Laboratory for
  evaluation.

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Warm Auto-Antibody Study

• Direct anti-globulin test results

An acid eluate is prepared and tested. Results
are on the following slide.
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The presence of a positive IgG DAT and
indications of anemia, along with a broadly
reactive eluate, are suggestive of a warm
autoantibody. However, the lack of reactivity of
some cells tested at PEG/AHG could indicate
either an allo-antibody or an auto-antibody with
an apparent specificity in the patients serum.
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• Since some auto-antibodies have specificities in
  the Rh system, a selected cell panel of e antigen
  negative cells is tested at PEG/AHG with the
  following results.

This selected cell panel indicates that all
allo-antibodies except anti-e are ruled out on at
least one cell. Our protocol is to rule out all
antibodies on at least two homozygous cells, when
possible. More selected cells are tested.
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• These cells rule-out all common allo-antibodies
  twice and confirm the presence of anti-e in the
  serum. At this point, a complete phenotype is
  performed. Having a complete phenotype is
  desirable due to the presence of a warm
  auto-antibody in the eluate AND to investigate if
  the anti-e in the plasma is allo- or auto- in
  nature.

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Warm Auto-Antibody

• In order to get an accurate phenotype on a
  person who has been transfused in the last three
  months, a cell separation must be performed.
  This separation can be accomplished using a
  micro-hematocrit centrifugation technique. Since
  neocytes are less dense than transfused (more
  mature) red cells, spinning the blood in a
  micro-hematocrit centrifuge leaves the patients
  own cells (the majority of the neocytes) at the
  top of the column of each capillary tube. Since
  the patient has a positive IgG DAT, the neocytes
  thus obtained are then treated with EGA to
  dissociate the antibody from the cells, allowing
  AHG testing to be performed. The treated cells
  are tested using a 6 albumin enhancement at AHG
  to confirm that reactivity is not observed at the
  AHG phase of testing.

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Testing the EGA treated cell separated cells gave
the following results
The negative IgG DAT, along with no reactivity
with 6 albumin indicates that the EGA treatment
was successful. The reactivity observed with the
patients plasma against the patients DAT
negative cells confirms that this is an
auto-antibody. When testing cells obtained by a
cell separation technique, great care must be
taken to watch for mixed field reactivity in all
testing performed. An error in reporting a mixed
field reaction as positive, could lead to
reporting an auto-antibody when in reality, the
antibody is allo- in nature.
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Warm Auto-Antibody

• The patient types as negative for c, E, S, K,
  Fya, and Jkb. In addition, the patient types as
  e antigen positive, which is consistent with a
  warm auto-antibody with apparent e-specificity.
  To confirm this, a differential adsorption is
  performed using e antigen negative cells. A warm
  auto-e can be adsorbed out using e-antigen
  negative cells, an allo-anti-e will not adsorb
  out the warm auto. Differential adsorptions were
  performed and tested against the adsorbing cells
  to confirm that the auto-antibody was fully
  adsorbed.

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• The X 3 adsorbed plasma is tested against the
  e-antigen positive cells with the following
  results

The lack of reactivity observed with the adsorbed
plasma indicates that the anti-e is auto in
nature.
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Warm Auto-Antibody

• A compatibility screen is performed using
  e-antigen negative units.

The crossmatch would be reported out as
incompatible with a comment that reactivity was
not observed using 30 minute/no enhancement.
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Conclusion

• This patient exhibits a warm auto-antibody with
  apparent e specificity. Different laboratories
  may use different nomenclature in reporting these
  antibodies. Warm-auto-anti-e and e mimicking
  auto-antibody are just two of the ways that
  auto-antibodies with a specificity have been
  described in the more recent literature. We
  routinely use the terminology of warm
  auto-antibody with an apparent x-specificity.
• Transfusion recommendations can be difficult to
  assess for patients with this type of
  auto-antibody. The initial thought is to give e
  antigen negative units since they may be
  crossmatch compatible. However, the
  auto-antibody often reacts more strongly with the
  fresher cells from a red cell unit than with the
  older cells found in screens and panels. Looking
  at the phenotype of this patient indicates that
  the patient can form anti-c and anti-E. Various
  studies have indicated that approximately 30 of
  patients exhibiting a warm auto-antibody have
  underlying allo-antibodies present. Transfusing
  this patient with e negative units means that
  they will be receiving cells that are positive
  for c and E. This could increase the possibility
  of the patient forming these allo-antibodies.
  Other studies indicate that, at best, the e
  negative units may have a slight increase n cell
  survival rate. Also, e antigen negative units
  may not be available as in when an O Negative
  individual has a warm auto-antibody with e
  specificity.

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Conclusion

• Warm auto-antibodies with apparent specificities
  are actually antibodies to antigens found on all
  red cells that serologically appear to be
  specific to one of the common allo-antibodies.
  The fact that they can be adsorbed out using the
  appropriate antigen negative cells demonstrates
  that the auto-antibody is e-like rather than an
  allo-antibody. Warm auto-antibodies have also
  been reported with specificities to antigens in
  the Kell, Duffy, and Kidd systems as well as
  others.