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Amra23

Human versus monoclonal reagents

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Posted (edited)

Silly question...,but I'd really like to know,what is the difference in choosing between human and monoclonal reagents for ABO/D testing? Is it a first choice from these two?Is it the price?
I work with Bio-Rad reagents and I know they have cards with human reagents but also identical cards with monoclonal reagents.Our lab use only monoclonal ones.
 

Edited by Amra23

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A few things as far as human reagents.

Firstly, you never know what else may be in them in terms of antibodies directed against low prevalence antigens, because there is absolutely no way that the producer has the ability to test for all such specificities (I can remember once a human-derived anti-D reagent produced at one of the places I worked, also had a Gm antibody in it that we didn't know about.  It is highly unlikely that this would have caused too many problems, but there is, nevertheless, a small chance that this could have caused a false positive).

Secondly, you never know what else may be in them in terms of viruses, some of which may, as yet, be unknown to us (remember, HIV, used not to be known).  This is a danger to the producer and the person using the reagent, rather than the patient.

Thirdly, the avidity of human reagents is, in general, pretty poor (particularly anti-D).

A few things concerning monoclonal reagents.

Some of them cross-react with other specificities (although not many), but, famously, monoclonal anti-D reagents will react with the I and i antigens if used straight from the fridge.

They have to be blended by experts to ensure that the desired epitopes are detected, but certain Partial D types (e.g. Partial D Type VI) are not detected (unless required).

They are very specific and very avid (both of which are greatly to be desired).

Virally, they are almost certainly sterile.

Hope that helps.

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Quote

Thank you,Malcom!

''monoclonal anti-D reagents will react with the I and i antigens if used straight from the fridge.''

I didn't know that! This is something I will always have to remember!

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1 hour ago, Amra23 said:

I didn't know that! This is something I will always have to remember!

It is, nevertheless, true.  

Thorpe SJ, Boult CE, Stevenson FK, Scott ML, Sutherland J, Spellerberg MB, Natvig JB, Thompson KM.  Cold agglutinin activity is common among human monoclonal IgM Rh system antibodies using the V4-34 heavy chain variable gene segment.  Transfusion 1997; 37: 1111-1116.

Thorpe SJ, Ball C, Fox B, Thompson KM, Thorpe R, Bristow A.  Anti-D and anti-i activities are inseparable in V4-34-encoded monoclonal  anti-D: the same framework 1 residues are required for both activities.  Transfusion 2008; 48: 930-940.

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Also, the polyclonal (human) reagents will give false pos results in samples with pos DATS.  But anyway, finding sufficiently good human antibodies to manufacture reagents from is getting harder and harder.  So definitely monoclonal

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2 hours ago, Amra23 said:

I wonder why they still manufacture human reagents if that's the case...

Because, believe it or not, there are some dinosaurs out there who still demand them, because they don't trust monoclonal antibodies, and they are senior enough (God knows how) that they cannot be over-ruled.  If sufficient people still want them, people will still produce them and sell them to the dinosaurs, at higher and higher prices.

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