I remember that certain antigens (and certain antibodies) are killed by
paraformaldehyde fixing; I have not heard of flourochromes being affected
in the same way, but check it out anyway.
Sorry I can't find a list of affected stains, I'm sure those who work a
lot with fixed cells can provide some specific info.
The best test is simply to stain some cells, read them fresh, fix, then
repeat the reading.
Joseph.
-- Joseph Webster (O.I.C. Flow Cytometry) Centenary Institute of cancer Medicine & Cell Biology Locked Bag No.6, Newtown, NSW 2042, AUSTRALIA. Ph: 61-2-565-6110 Fax: 61-2-565-6101