Can some one offer an answer to my problem

Barren, Phil BarrenP at
Fri Jun 4 16:39:10 EST 2004


I have an investigator that is staining Raji and Jurkat cells with anti Human HLA-DR (
APC or PE)

When he stains Raji alone, he gets a nice shift to about 3,000 MCF (log). (This cell line
is positive for HLA-DR)

When he stains Jurkat alaone, he gets an MCF of about 3. (This cell line is negative for

When he mixes the cells together ( 1:1) and stains with anti Hu HLA-DR, he sees a shift
in the Jurkat population MCF. It is now 11

The Raji have the same 3,000 MCF.

All staining is done at 4C on ice with a 30 minute incubation.

Can anyone offer an explanation why the negative population ( Jurkat) is becoming more
positive with the anti HLA-Dr Mab when the staining is done with both cell types present
versus staining the cells alone.

The 4C staining, one would think would eliminate any activation starting in the Jurkat

Have a good weekend and thank  you for taking  the time to ponder this


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