Hi everyone,

We have seen some patients that are demonstrating anti-K with PEG only.  We repeat with Gel and tube LISS and results are negative.  We change our incubation times and still negative, we have used K homologous cells in gel and still negative.  Anyone have any hints as to why this is happening.

Chris

PEG-only antibodies are well known, but it's common that they can also be detected in one of the other very sensitive methods (Gel or Solid Phase). The LISS method is less sensitive than PEG and it's not surprising that you can't detect it there.

It is possible that the PEG reagent contains a chemical that is critical to the reactivity of your patient's particular antibody. There are lots of documented examples of "chemical-X-dependent" antibodies. The absence of the specific chemical from the LISS test and the Gel system would render it nonreactive/undetectable.

Trying another manufacturer's PEG reagent (presumably with a different formulation) might clarify the situation.

If you read the manufacturer's instructions for Ortho Gel it says: "In some low ionic strength test systems, certain antibodies, such as anti-E and anti-K, have been reported to be nonreactive."

1 hour ago, goodchild said:

If you read the manufacturer's instructions for Ortho Gel it says: "In some low ionic strength test systems, certain antibodies, such as anti-E and anti-K, have been reported to be nonreactive."

Good point. I know that the Gamma/Immucor PEG reagent available in the US does have low ionic properties. Don't know about other suppliers, but it's common for reagents like these to be very similar.

But we are seeing anti-K and anti-E in gel; so is it the genetics of these antibodies or is it that they are so weak that gel just does not pick them up? 

 

Could be either. In my experience, PeG is a bit more sensitive than gel. When we had nebulous reactions in gel, we resorted to PeG to ID the antibody.

I think it's always valuable to remember that there is no one system that will detect all antibodies, even within the same specificity - that's just life (or maybe I should say, that's just biology).