[Histonet] RE: Endogenous biotin ??

[Malam Jacqueline]

I am trying to help someone from another hospital who is having immuno
problems with non-specific staining in some of their negative controls when
using a Ventana Benchmark. I also got the same staining using their slides
on my Benchmark XT. It can appear in mucin-producing cells of e.g. gastric
tissue, lymphoid tissues and rather spectacularly in Leydig cells in testis,
but it does not appear in the same type of tissues all the time nor does it
appear when they do manual antigen retrieval and use their Ventana Nexus.
The staining pattern has the appearance of endogenous biotin and testis does
indeed contain biotin; but I would have thought that any endogenous biotin
in the tissues would have shown up on the Nexus-stained slides which had
manual antigen retrieval. I am wondering if there is some neuro-endocrine
involvement rather than biotin. Ventana have been extremely helpful but are
also scratching their heads too! The only significant difference between the
two methods is the fact that manual antigen retrieval is performed at a much
higher temperature and for a shorter time than the Benchmark. Fixation,
processing, reagents and equipment malfunction has supposedly been ruled
out.
Your help and comments would be much appreciated by us both.

Jacqui



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