anti S gives false neg with TSEN+ cells

[Mabel Adams]

The package insert with our new lot of anti-S includes a statement that TSEN+ S+ cells may give a false negative reaction with this anti-S. How concerned should I be that we could miss an S antigen in our occasional use of it for typing patients and screening units?

[Rh-fan]

The frequency of the TSEN antigen is very low. Also in donortyping the problem is is not that big because you always perfom a cross-match after you have typend the donor (you can see that as a second typing with a polyclonal anti S (made by the patient)).

In patient typing it is no problem at all. When you type the patient "fals" S negative, you think the patient can make an anti S. No problem.

Peter

[Malcolm Needs ☆]

AS ever, Peter is completely correct, but, to give you some idea about just how rare are TSEN+ individuals, Reid, ME, Lomas-Francis C, Olsson ML, The Blood Group Antigen FactsBook, 3rd edition, 2012, Academic Press quote the frequency of TSEN+ individuals as <0.001%! You would, therefore, be VERY unlucky to come across a TSEN+, S+ individual, but, of course, unlucky doesn't mean you won't!!!!!!!!!!!!!

[Mabel Adams]

That's what I had concluded, but I wanted to hear some other people say the same thing. The only risk with donor screening would be for the patient with the weak or historic only anti-S and they probably are not as likely to have a serious reaction due to low titer or anamnestic response. All of these things happening at once would be extremely, extremely rare. Thank you for supporting my conclusion.