At 03:27 PM 5/9/01 -0500, Plummer, Timothy B. wrote:
>Does anyone know of a technique for blocking the cells in lymphoid >specimens which exhibit intense green (FITC wavelength) >autofluorescence?

The most effective (100% complete) way to block 
autofluorescence in paraffin sections is to treat briefly
with a dilute osmium tetroxide solution and follow this
with a very thorough washing in water.  I did this quite 
often in the late 1960s and early 1970s in conjunction 
with fluorescent carbohydrate histochemistry; 
there are also published references. I can't remember
the details, but it's something like 0.25% OsO4 for
10 mins then 2 hours in running tap water. The sections
don't become blackened by this osmium treatment. Other
published methods of the day were _much_ less effective.
They included treatments with mercuric chloride and
with ferric salts. 

If you want to do this, let me know and I'll dig out 
the old papers and send you the particulars.

John Kiernan
London, Canada.