Neil Blumberg

Thanks Malcolm. Never say never :).

"I'm sorry Neil, but Geoff Daniels quotes some HTR's caused by anti-N reacting at 37oC," These are, if I remember correctly, fairly ancient reports and I have never seen nor heard of a case of hemolytic transfusion reaction or HDFN due to anti-N despite having had hundreds of patients with anti-N in our service over the last half century. I've never heard of anyone else seeing one. So this is very possibly a case of old reports of hemolysis due to other causes (undetected antibodies for example). Methodology for antibody detection in the 1940s and 1950s, and even 1960s, was significantly less sensitive and accurate than currently. There are reports mentioned in Mollison and other comprehensive texts such as Daniels of hemolytic reactions due to antibodies (e.g., anti-P1, anti-Leb, etc.) that have never been reported in modern literature (the last 30-40 years). This makes me suspicious that these old reports are mistaken as to the cause of hemolysis. If the mother has an anti-N and the infant is not hemolyzing, and the antibody is undetectable I would not transfuse N negative blood. If the infant is hemolyzing, that is another story, obviously. A positive DAT, hemolysis and anti-N in the mother would dictate prudence and transfusing N negative blood. But I will stand by my original comment, which is that anti-N almost never causes clinically significant hemolysis in transfusion recipients nor in affected fetuses. Absent clinical and laboratory evidence for anti-N causing the infant's anemia, there is no reason to transfuse N negative blood when the antibody is not detectable in the fetus/infant.

Anti-N does not cause hemolytic Transfusion reactions nor hemolytic disease of the newborn and fetus. So I would not give N negative blood in general, nor if the cross match is negative.

Not an approach we would use. Alloimmunization rate in autoimmune diseases is generally quite low, including aplastic anemia.

Also, were any of the transfused units antigen positive? This is the quickest way to get a negative indirect antiglobulin test ;).

Was the patient transfused? If not, hyper hemolysis is less likely. Sounds like mechanical causes are most likely.

Patient should be monitored for a delayed hemolytic transfusion reaction for about 10-14 days, not necessarily in hospital. Most common signs are fever and progressive anemia. sometimes dark urine or jaundice. Patient education before discharge if earlier than this is essential.

No, not an error.

If the donor passes your screening questions and seems clinically fine overall, there is literally no need to worry about these issues, either in terms of donor or recipient safety. The history and physical exam are by far the most important information in evaluation of patients or donors.

Not yet available. Being developed by Grifols. Probably months to a year away from FDA approval. You can contact them about becoming a testing site for licensure I'd guess. Until it's licensed you won't be able to use it in patient care, just research/validation.

Thanks Malcolm. Not pedantry at all. These exceptions are relevant and potentially important, particularly for ABO.

Ideally one avoids infusing plasma containing antibodies to recipient antigen. Of course it’s always a bad idea to transfuse antigen to which the recipient has antibodies. We often forget that after transplant all of the recipient cells except the blood cells and immune cells are of the original phenotype. We often forget that after transplant all of the recipient cells, except the blood cells and immune cells are of the original phenotype. In this case group AB cells might be safest with no incompatible antigen or antibody. Group A would be my next choice and I would wash or plasma reduce to get rid of the anti-B which will interact with the recipients endothelial cells, soluble antigen and all non-hematopoietic cells of the recipient. Some folks would use group O red cells which I think is probably the worst possible choice given the potential anti-A and anti-B. Washing or volume reduction would minimize this risk.

When you have incompatible antigen or antibody, low level hemolysis occurs, probably with complement activation. This is not at levels clinically evident, but inflammation occurs. Inflammation potentiates (increases) B cell activation and provides one mechanism by which ABO non-identical red cell transfusion (without washing) increases rbc alloimmunization to other antigens being presented. It is known to the case, both from clinical observations (referenced in my previous post) and from animal models which provide evidence that the presence of inflammation increases alloimmunization to red cells and other antigens. It's the mechanism by which adjuvants in vaccines increase immunization to microbial antigens in vaccines, by the way. Inflammation. Not a good thing if you are not infected and receiving transfused antigen :). But useful if you are trying to get a beneficial immune response to an antigen.

Whole blood only makes sense for patients with life threatening bleeding. Red cells are safer for patients who have major anemia/minor and/or slow bleeding. Whole blood will put many patients who are not hypovolemic into cardiac failure/pulmonary edema, and are, in general more toxic than red cells alone.

If you need copies of these reprints or have further questions, happy to help.