So we know that at times we add extra plasma to increase detection of weak antibodies. But my question is, has anyone done this with GEL testing?  The instructions clearly state to use 25ul of plasma so just curious as to whether that is even an option with that technology?

Thanks,

Brenda Hutson, MT(ASCP)SBB

No.

Scott

NO!  Definitely not.  It will alter the ionic strength.

Thanks, that was my thought too (going round with new supervisor on this).

Brenda

Adding more plasma than 25 micro liters to a gel card test would not be following manufacturer's directions. It would require a validation study in order to implement.

3 minutes ago, Avid1234 said:

Adding more plasma than 25 micro liters to a gel card test would not be following manufacturer's directions. It would require a validation study in order to implement.

Not only would it not be following manufacturer's directions - it also wouldn't work!  This has nothing (particularly) to do with gel technology, but everything to do with ionic strength.  It would be worth reading Elliot M, Bossom E, Dupny ME, Masouredis SP.  Effect of ionic strength on the serological behaviour of red cell isoantibodies.  Vox Sang 1964; 9: 396-414, Hughes-Jones NC, Gardner B, Telford R.  The effect of pH and ionic strength on the reaction between anti-D and erythrocytes.  Immunology 1964; 7: 72-81 and Löw B, Messeter L.  Antiglobulin test in low-ionic strength salt solution for rapid antibody screening and cross-matching.  Vox Sang 1974; 26: 53-61, in particular, in my opinion, that of Nevin Hughes-Jones et al.

Thanks for all of the resources Malcolm (and yes, I did also point out it would not be following Manufacturer's instructions).  You remind me of a former Pathologist from "years" ago that I have always stayed in touch with and ask questions of from time to time......he is like a walking library for resources that back what he tells me.  I will pass yours on to my new supervisor .

Brenda

On 12/28/2018 at 7:40 AM, Malcolm Needs said:

Not only would it not be following manufacturer's directions - it also wouldn't work!  This has nothing (particularly) to do with gel technology, but everything to do with ionic strength.  It would be worth reading Elliot M, Bossom E, Dupny ME, Masouredis SP.  Effect of ionic strength on the serological behaviour of red cell isoantibodies.  Vox Sang 1964; 9: 396-414, Hughes-Jones NC, Gardner B, Telford R.  The effect of pH and ionic strength on the reaction between anti-D and erythrocytes.  Immunology 1964; 7: 72-81 and Löw B, Messeter L.  Antiglobulin test in low-ionic strength salt solution for rapid antibody screening and cross-matching.  Vox Sang 1974; 26: 53-61, in particular, in my opinion, that of Nevin Hughes-Jones et al.

Hello, I just thought about a question related to gel testing. Would it be fine if neutralized plasma (for example, as part of antibody identification for Chido/Rodger) is tested in gel card? I have always tested neutralized plasma in tube method but always wondered if gel testing would work when I am short of test plasma. I only have to use 25ul of plasma in gel instead of 2 drops (100ul) in tube method. Thank you for useful references and being a great resource here for us, Malcolm! 

12 hours ago, dothandar said:

Hello, I just thought about a question related to gel testing. Would it be fine if neutralized plasma (for example, as part of antibody identification for Chido/Rodger) is tested in gel card? I have always tested neutralized plasma in tube method but always wondered if gel testing would work when I am short of test plasma. I only have to use 25ul of plasma in gel instead of 2 drops (100ul) in tube method. Thank you for useful references and being a great resource here for us, Malcolm! 

Yes, whenever we thought that there was an ant-Ch or an anti-Rg present in my Reference Laboratory, we always tested the inhibited plasma by gel card.

Thank you for your kind comment at the end of your post.

There is absolutely no problem testing for Ch/Rg in gel.  And although it should not be ok to use 50ul plasma instead of 25, actually it does SOMETIMES enhance very weak antibodies.  There have been times when I have done this successfully.  You will not however find it in the official instructions for antibody screening/identification and this should never be done as a routine technique