Screening Antigen Negative Units??

[Johnny]

Can someone tell me what the requirements are for performing antibody identification. We want to do a ten cell panel and finalize it with the Fishers Exact method to confirm antibody using a 3 positive 3 negative cells. Wondering if this enough. Thanks:)

[FRahman]

Yes. There is a site called MCN Healthcare. Visit this site homepage and look under policy and procedure. then look under clinical laboratory procedres. You will find blood bank policies and procedure. Unfortunately it is not free. You can buy the whole pkage. Hope this help.

1) I'm simply curious if it is an acceptable practice to save patients' plasma with a known Antibody to SCREEN for antigen negative units, then confirm (Test of Record) the antigen typing with our commercially purchased antiserum? If this an acceptable practice, how do we verify and control the screening plasma for use? I was thinking of running two positives and one negative qc with each run. The positives would be one heterzygous cell and one homozygous cell, where the graded results must be at least a 2+. Then my next question is how long is would this screening plasma be good for? I was thinking 2 months, or until the qc is not valid, which ever comes first. Any help with this process would be greatly appreciated. Any procedures that I could use as references, would also be greatly appreciated. This idea has cost saving benefits, but I'm just not sure how to implement it properly.

2) Is there a web site (bloodbanktalk.com or elsewhere) that Blood Banker can swap and share policies and procedures? I'm always looking for references, to help write policies or procedures.

thanks for everyones willingness to share!!! Have a GREAT DAY!

[Malcolm Needs ☆]

This, of course, is of no relevance to people in the USA, but in the UK we are "governed" by Guidelines issued by the British Council for Standards in Haematology. In respect of antibody identification, these state that to positively identify the specificity of an antibody, the plasma must react with two examples of red cells expressing the antigen (usually as a "double dose"), and not react with two examples of red cells that lack expression of the antigen. In addition, antibody specificities against other clinically significant atypical alloantibodies directed against the major blood group antigens must be excluded.

This can be exceedingly difficult on occasions (e.g. when the antibody is directed against a very high frequency antigen, such as Rh29, or when there is a complex mixture of "common" antibodies). In such cases, it is worth remembering the usefulness of adsorption and elution to elucidate the case.

One word of caution. If you are faced with identifying the specificity of an antibody against a low frequency antigen (although this exercise is usually esoteric, rather than useful!) be aware that many red cells labelled as positive for a particular low frequency antigen may, in fact, NOT be positive for this antigen. Unless they have been typed using antisera that are known to be monospecific, or have been checked at a molecular level, they may have reacted with a second specificity within the grouping reagent, as individuals making an antibody directed against a low frequency antigen often produce a "soup" of antibody specificities against low frequency antigens.

[Ellen Zeigler]

As several have said, patient plasma/serum is acceptable for screening purposes. If you have enought to aliquot and freeze (best the lower you go temperature wise). You can use controls if you choose, however, as you need to repeat with licensed antisera (and controls) why bother unless over time the serum has become unreliable...

[Malcolm Needs ☆]

I couldn't agree more with Ellen Zeigler. The use of controls, particularly negative controls, with such antisera as an anti-U, whilst just screening, is a criminal waste of a very precious reagent cell.