Case study of a patient with both red cell autoantibodies and alloantibodies

A transfusion medicine physician in Massachusetts reports on an Rh(D) positive, C-positive, c-positive, E-negative patient whose serum currently demonstrated anti-E. The patient had not been transfused for several years, but had a positive direct antiglobulin test (DAT) on 1/13/03 that was 1+ with anti-IgG AHG and negative with anti-C3d AHG. An eluate demonstrated auto anti-c, which was NOT detected in the patient's serum using standard techniques employed by the inquiring blood banker's laboratory. The question raised by the Massachusetts blood banker is, "In the event transfusion becomes medically necessary, which Rhesus phenotype would colleagues select?"

BEFORE the inquiring physician's laboratory discovered that the patient was in fact both "big C" and "little c" positive, they reasoned that it would be important to avoid the possible action of auto anti-c on transfused c-positive donor red cells, but if the patient was 'big C' negative they would also be concerned that the transfusion of c-negative R1R1 blood (to 'honor' both the auto anti-c and the allo anti-E) might cause the development of allo anti-C (since R1R1 RBCs are C-antigen positive). Others argued that because the serum did not show auto anti-c reactivity, it would be safe (and preferable) to ignore the auto anti-c and simply use E-negative units, and merely honor the alloanti-E.

Followup for the above case was interesting and perhaps instructive. The patient received two units of E-negative RBCs; however one unit was c-positive and the other was c-negative. Although neither transfusion was associated with a reported reaction, the patient's hematocrit only rose from 28.6 to 30.0 following transfusion. Four days post-transfusion the patient's hematocrit fell to 25.1. The inquiring physician did not feel bleeding was a complicating clinical factor. A specimen submitted on the fifth post-transfusion day (1/18) showed anti-c in the serum, along with the anti-E. The DAT on this sample (5 days following the transfusion of the c-pos and c-neg units) was still 1+ for IgG and negative for C3.

How would other colleagues address this case? When responding to this query, please provide a scientific basis for your input.

The following response was received.

ADDENDA Jan. 28, 2003

1. A colleague currently working for the English National Blood Service in Liverpool reports that at their red cell reference department they have many patients known to them with both auto & allo-antibodies. According to the responding colleague, it is their current practice to give ABO/ D and K antigen-matched blood in cases such as these. In the described case their approach would have been to ignore the autoantibody regardless of whether or not it was demonstrable in the serum. Indeed, they often find that autoantibodies appear, disappear and reappear depending on the patient's state of health. The responding coleague would be interested to see if the patient's autoantibody goes on to become panagglutinating in the near future (in their experience, the autoantibody rarely stays specific, usually becoming strongly panagglutinating). The biggest problem they report having in cases such as these is that patients are often transfused before they get the chance to phenotype them. This makes distinguishing auto from allo very difficult!! It is interesting that the reported patient's autoantibody had anti-c specificity, because they personally have only seen autoantibodies with anti-e specificity.

ADDENDA Jan. 29, 2003

2. A blood banker from a major university in Ohio (that has a national champion football team, at least for now) reports that at his institution they would approach the case under discussion by transfusing RBC units that lack both the E and c antigens, until such time as the auto-anti-c is no longer demonstrable in the eluate. Apparently their policy is to respect the specificity of a warm autoantibody, if possible, until the autoantibody no longer exists. Iin this case they would avoid challenging the anti-E (because it is an alloantibody), and avoid challenging the autoanti-c, (until it is no longer detectable in both eluate and serum). The responding blood banker did not provide a scientific reference to support this approach, but did comment that it was based on personal experience.

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