You have touched on something that I am interested in. While I am sorry that I have little to add, perhaps my intrigue may provide insight into your "too bright problem" with the secondary antibody. You stated that the monocytes were separated with ferritin-conjugated anti-CD14. So, what is the 'fluorescence/reflectance' of these antibodies? I know that on endothelial cells the ferritin conjugated antibody does not just 'come off' after separation and it stays there through culture. So, perhaps some of the 'background' is widely varying amounts of ferritin-anti-CD14? your thoughts on this would be appreciated, thanks Bob Bowden -----Original Message----- From: Maciej Simm [mailto:simmmmer@yahoo.com] Sent: Tuesday, August 01, 2000 2:55 PM To: cyto-inbox Subject: need advice on choice of 2nd step antibodies Greetings everyone, We're about to commence some human monocyte studies. The primary antibody will be either mono- or poly- and unlabeled. The poly- is Rat anti Human, the mono is Mouse anti Human. We did a quick run just to see if it would work right away but no, it didn't. The secondary antibody is too bright even without the primary. questions: 1. what is a good blocking solution for rat-anti-human followed by goat-anti-rat stains? The researcher has tons of "goat premium serum". How about BSA? Are there any antibodies or commercial kits available to block the FC receptors on Monocytes? 2. are there any FC-truncated something-anti-mouse FITC labeled antibodies commercially available? (IgG1) 3. finally, to be scientific, we should include a monocyte marker (even though the monocytes are pre-magnetically sorted using CD14) Should we use FITC/PERCP combo? I think that would be easier to compensate (compensation was a big topic these days) considering our FITC is MUCH brighter than the "calibrate bead level". I have to turn the voltage WAY down just to get it in the 4th log, and that's the 2ndary only control :) any other pointers, or suggestions would be greately appreciated as always. Thanks! Maciej __________________________________________________ Do You Yahoo!? Kick off your party with Yahoo! Invites. http://invites.yahoo.com/
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