I am looking for a recipe for a dilute antisera that can be used in daily QC. This standard says using antiserea of 1+ or greater avidity.

I am relatively new to a hospital that makes 50 ml of dilute anti-D. It degrades over time and is then 'spiked' to give acceptable results. Needless to say, I am not comfortable with this and am wondering what other places do. At my previous job we only made up 5 ml at a time and the strength of reaction held throughout.

So, any recipe and also expiration of the dilute antisera would be great!

Any help would be appreciated.

Thank you.

We make up a pretty good-size batch of diluted Anti-D that is tested and demonstrates the desired strength of reaction (ie: 1+.) Then we label a big batch of 10 X 75 mm tubes and put 2 drops of the diluted antisera in each tube, parafilm the tubes & freeze. So everyday the tech pulls out however many tubes are needed to do the QC each day, thaws them (only takes a few minutes), and performs the QC testing. Our frozen batches never seems to lose its strength during storage in the freezer.

Donna

What is 'good sized'? And, do you have a recipe you would be willing to share?

Thank you for your help.

Our formula: Add one drop of Anti-D to 10 ml of normal human serum that is known to have a negative antibody screen. Perform your regular Antibody Screening on this dilution.

If the dilution demonstrates a strength too weak or too strong, add more Anti-D or more normal human serum and retest; repeat until you get the desired antibody strength. (Ours is usually spot-on.)

Divide this diluted antisera into 2-drop aliquots in 10 x 75 mm tubes, parafilm, and store the tubes in the freezer to use for the next several weeks.

Why are you making a dilution? The standard used to be a rx of 1+, now it is 1+ or greater. I guess it goes a long way. If you use a 3 cell screen how do you qc your rr cell? Can't do the positive with anti-D.

The 3-cell screen we use is R1R1, R2R2, and rr. We have 2 positives and 1 negative.....is that what you mean? I do see the 1+ or greater avidity. So, David, what are you currently doing?

Thank you for your help.

Why are you making a dilution? The standard used to be a rx of 1+, now it is 1+ or greater. I guess it goes a long way. If you use a 3 cell screen how do you qc your rr cell? Can't do the positive with anti-D.

I like to know that our rotating techs will detect a 1+ when they perform the daily reagent QC. (ie: You could have an unacceptable forceful resuspension technique and still detect a 3+ rxn.)

As Ardele wrote in her post above, our rr screening cell is expected to be Negative when we test it with our diluted Anti-D.

Donna

Why are you making a dilution? The standard used to be a rx of 1+, now it is 1+ or greater. I guess it goes a long way. If you use a 3 cell screen how do you qc your rr cell? Can't do the positive with anti-D.

We do a mix of anti-D and anti-c (or anti-e). We get the antibodies from plasma that the blood center finds in their donor population. You could use other high frequency antibodies for your rr cell, but they may be less willing to part with those. A donor antibody is often naturally at the strength you are looking for.

A donor antibody is often naturally at the strength you are looking for.

As I have said elsewhere on this site, many times before, this is exactly what is need in terms of antibody strength. Antibody/antigen reactions follow the Law of Mass Action, and so the equilibrium constant of the reaction is different for a "real" weak antibody and that of a diluted strong antibody, and the latter will give you a false sense of security, and is a "false" positive control.

The standard is" "Each cell for antibody detection must be checked each day of use for reactivity of at least one antigen using antisera of 1+ or greater avidity". Weak anti-D does not allow for compliance if you use a 3 cell screen . . . I know - it is the reactivity you would expect, and I agree, but the standard is as it is. I believe the CFR also requires demonstration of reactivity - not non-reactivity (unless you use gel in which case you have to run positives and negative). I do absc in gel . . . I use the CorQc ab diluted 1:10 and diluent as the negative.

Edited July 15, 201114 yr by David Saikin
spelling

Thanks, David. Once you quoted the actual standard, I see that you are correct (and I am not.) Would mixing a second antibody (that would agglutinate the D Neg Screening Cell) in with the weak Anti-D be my best resolution? (Oh, boy......I hate making a new truth table for our computer and validating it!!!)

Donna

Certainly . . . the standard does not define how to do it, just what must be done.

I want to thank David also. Now after reading the standard I see we are not compliant either! So, we are looking into the commercial QC kit prepared by Immucor - corQC Test System. This is solely for tube methodology and will not replace the QC materials for the Echo. I think it would be a good way to go, as we are a system currently with 5 hospitals. It would ensure standardization across the 5 hospitals. Thanks for all who responded.