(4) If the autoantibody shows clear specificit, (for example, anti-hr "(e)),
blood should be selected lacking that particular antigen; there is evidence that such
cells will survive much better than the patient's own cells. If partial specificity is
indicated (for example, titration technique revealing higher scores with hr"(e)-positive
than hr"(e)-negative blood), the use of hr"(e)-negative blood is debatable. Limited data
suggest that such blood may survive longer than the patient's own cells. In many cases
of AIHA, no specificity is obvious, the patient's serum reacting with all normal cells
tested (but perhaps marked variation is noted with cells of different donors). In cases
such as this, many workers carry out compatibility tests on a large number (for example,
8 to 12) of donor units and select those units that give the weakest reactions "in vitro."
Although there are no data to prove significantly better RBC survival of such
comparatively weaker reactive units, it is at least esthetically pleasing for the blood
transfusion laboratory personnel to issue the least incompatible units.
(5) Some investigators recommend ignoring the "specificity" of the
autoantibody and, after excluding the presence of alloantibody, giving blood that is the
same Rh phenotype as the patient, if feasible, in order to avoid the subsequent
development of Rh alloantibodies. Such investigators emphasize that data regarding
the "in vivo" significance of autoantibody specificity are scanty; however, it is also true
that a significant minority of warm autoantibodies will react quite specifically with one or
another of the Rh antigens, and no data exists to prove that such specificity is
insignificant.
(6) Even though all blood tested is incompatible with autoantibody,
transfusion may be indicated and may be a life-saving measure in cases with severe
and progressive anemia. The warm auto antibody is unlikely to cause an acute
hemolytic transfusion reaction and, although RBC survival may not be normal, the
temporary benefit may be of great value until other therapy (for example,
corticosteroids, splenectomy) is effective in producing more lasting benefit.
(7) In summary, transfusion therapy should be employed only in life-saving
situations with the realization that responses are palliative and that incompatible blood
is being employed. An attempt should be made to differentiate autoantibody from
alloantibody in the serum. If specificity is obvious, appropriate donor blood should be
selected.
NOTE:
Blood should never be withheld from patients with severe life-threatening
nemia because of incompatibility resulting from autoantibodies.
MD0846
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