We have a patient with an anti-K plus possible anti-Jsa (positive with 2/3 Jsa+ cells).  I noticed that the guidelines say we should provide Jsa neg units for this patient. As we are unable to Jsa type cells we cannot be 100% sure they are Jsa negative. I wondered if anyone knew why they have to be antigen negative when other antibodies to low incidence antigens are just IAT  compatible?

It all depends upon how many times the specificity has been implicated in a transfusion reaction, how significant was the reaction, and how frequent is the antigen in the donor population.

 

For example, anti-Wr^a has been implicated in transfusion reactions, and these have been deemed to be significant, but the frequency of the Wr(a) antigen is so low in most donor populations, and the reactions were only clinically significant when the avidity/titre of the anti-Wr^a was high, so that there would have been every chance that it should have been detected in the cross-match.

 

Therefore, in the UK, the screening cells and panel cells produced by the NHSBT are tested and are deliberately excluded if they turn out to be Wr(a+), and so we don't detect anti-Wr^a, which is far, far more frequent than the Wr(a) antigen.

OK. Thanks.. As I work in Scotland the frequency of Jsa+ donors will be lower than in NBS but I guess should he need blood we will have to discuss  with medical staff whether Jsa- blood should be sourced.