Hi all, 

Considering that recently transfused/pregnant patients may potentially be developing a new antibody which may still be of the IgM type. How important is it to test sample @ RT (or use polysecific AHG reagent) especially for transfusion-dependent patients? 

Thank you 

Most developing clinically significant alloantibodies still react at 37^oC, and so trying to detect them at room temperature is more or less futile as, in most cases, all you will detect are antibodies that  you do not want to detect, such as cold-reacting anti-M, anti-N, anti-P₁, etc, which would be a waste of time, reagents and, most importantly these days it would seem, money.

Most polyspecific or broad-spectrum AHG reagents these days are a mixture of anti-IgG and anti-C3d (particularly in the UK).  They do not contain anything but the merest hint of an anti-IgM (certainly, they would not be CE-marked for anti-IgM).  The other thing is that I am prepared to bet quite a lot of money that your laboratory is using EDTA-anti-coagulated samples.  This means that the Ca⁺⁺, Mg⁺⁺ and Mn⁺⁺ ions are all chelated from the plasma, which means that the complement pathway cannot be initiated in vitro, so, even if the de novo antibody was capable of "fixing" complement, the anti-C3d would not detect such an antibody anyway.

Therefore, as the number of recently transfused patients who are developing antibodies not yet detected by normal serological techniques who have been fatally affected by a further transfusion hasn't been great (zero in fact) and the same applies to pregnant ladies, stick to trying to detect clinically significant antibodies at 37^oC using monospecific anti-IgG.

GOOD QUESTION THOUGH - SHOWS YOU ARE THINKING!

17 minutes ago, Malcolm Needs said:

The other thing is that I am prepared to bet quite a lot of money that your laboratory is using EDTA-anti-coagulated samples

Yes, you are right sir.