Hazy reactions in Ortho Gel Cards

[silverblood]

If hazy reactions occur in Ortho Gel card antibody testing what does this signify? Would a hazy reaction be considered a positive or false positive reaction and how would one proceed to resolve this problem? Would one proceed to a gel panel or first use another method ( i.e. tube testing) ? How would one report such a reaction?

[Malcolm Needs ☆]

We get an awful lot of these sent in to us to resolve.

In almost all cases, there is no reaction detectable by DiaMed (BioRad) gel cards using both IAT and enzyme-IAT, and none by LISS tube IAT at 37oC.

We report these as no atypical alloantibodies detected.

[SMILLER]

After a while with gel you get an idea of what is junk and what is a possible weak reaction. But you have to be carefull -- screening cell sets are almost always all positive for M, for instance, so you can see how a weak reaction for that may look like "junk" panagglutination.

 

We would normally try a sreen in tube,  So if the tube screen is negative, we report that as a negative screen for the patient. 

Scott

[pstruik]

I agree with both the above posters - we used Ortho cards for many years in which time I was one of the (guilty) parties bothering Malcolm with 'junk' until we had built up enough experience to have the confidence of SMiller.

I always thought there tended to be a clearer meniscus at the top of the cell button with weak antibodies compared to 'junk'

We always maintained two different IAT techniques to resolve such problems, especially as some patients - eg with AIHA - were untestable by Ortho as they gave 4+ reactions with all cells however carefully we prewarmed everything in sight which would have made antibody screening and crossmatching something of a challenge unless we had an alternative technique available.

[tbostock]

We see this in patients with rouleaux. It either appears as a "mixed field" reaction, with agglutinates at the top and bottom, or a smooth uniform haze in the gel.

If it's just a haze with no agglutinates/clumps, we are now comfortable with reporting these as negative.

[jayinsat]

From my experience if I understand your description of "hazy reactions" correctly, is how Anti-M (IgM) often react.  A lot of the Anti-M's that I get are not your normal gel positive reaction.  Rather, they are a fuzziness up the gel column, usually on the Homozygous cells only.  I think I have seen this with some other colds as well.