| Assay Method Information | |
| | Inhibition Ligand Binding Assay |
| Description: | cAMP treated U937 cells expressing C5aR were centrifuged and resuspended in assay buffer (20 mM HEPES pH 7.1, 140 mM NaCl, 1 mM CaCl2, 5 mM MgCl2, and with 0.1% bovine serum albumin) to a concentration of 3×106 cells/mL. Binding assays were set up as follows. 0.1 mL of cells was added to the assay plates containing 5 μL of the compound, giving a final concentration of 2-10 μM each compound for screening (or part of a dose response for compound IC50 determinations). Then 0.1 mL of 125I labeled C5a (obtained from Perkin Elmer Life Sciences, Boston, Mass.) diluted in assay buffer to a final concentration of 50 pM, yielding 30,000 cpm per well, was added, the plates sealed and incubated for approximately 3 hours at 4° C. on a shaker platform. Reactions were aspirated onto GF/B glass filters pre-soaked in 0.3% polyethyleneimine (PEI) solution, on a vacuum cell harvester (Packard Instruments; Meriden, Conn.). Scintillation fluid (40 μl; Microscint 20, Packard Instruments) was added to each well, the plates were sealed and radioactivity measured in a Topcount scintillation counter (Packard Instruments). Control wells containing either diluent only (for total counts) or excess C5a (1 μg/mL, for non-specific binding) were used to calculate the percent of total inhibition for compound. |
| Affinity data for this assay | |
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