Monocyte Blocking...

Prevents live monocytes from non-specifically binding to fluorophores.

Monocytes and macrophages can non-specifically bind to fluorophore-conjugated antibodies used in cell surface staining of live cells. While there are some publications which propose this phenomenon may occur due to the function of CD64, Fc blocking does not ameliorate this effect. This effect is also not cyanine-specific. Our testing shows that PE/Dazzle™ 594, which is not a cyanine-based acceptor fluorophore, can exhibit non-specific binding to monocytes. On the other hand, cyanine-based fluorophores like Alexa Fluor® 647 and the cyanine-based acceptors of some of the Brilliant Violet™ tandems do not exhibit non-specific binding to monocytes. Our testing has shown this effect appears to be quite selective for any PE, PerCP and APC tandems. (please note that the tandem fluorophores of competitors were not included in our analysis).


BioLegend has now formulated an effective blocking reagent, True-Stain Monocyte Blocker™. It is a non-antibody based blocking solution that has been shown to reduce non-specific monocyte binding due to the fluorophore and does not affect the desirable specific staining of monocytes. To learn more about which fluorophores might require True-Stain Monocyte Blocker™, take a look at the chart to the right. To learn more about this reagent, visit our webpage.

Fluorophore conjugates recommended for use with True-Stain Monocyte Blocker™ Fluorophore conjugates that likely do not need True-Stain Monocyte Blocker™
PE/Cy5 Non-tandems: FITC, PE, APC, Pacific Blue™, PerCP, BV421™, BV510™, Alexa Fluor® 488, Alexa Fluor® 594, Alexa Fluor® 647, Alexa Fluor® 700
PE/Dazzle™ 594
APC/Fire™ 750 Brilliant Violet™ tandems: BV570™, BV605™, BV650™, BV711™, BV750™, BV785™

Human PBMCs were stained with 5 µl/test of antibody in 100 µl of cells at 1 x 106 cells/ml with (bottom row) or without (top row) True-Stain Monocyte Blocker™.