Complement C5a Receptor Assay for High Throughput Screening

Abstract

The complement C5a receptor on U937 cells, a human histiocytic lymphoma cell line, stimulated with dibutyryl-cAMP have been stabilized for at least 3 months at a diluce, ready to use concentration. [¹²⁵I]-Bolton Hunter labeled C5a, (recombinant, human) has been prepared by reverse phase HPLC to 2200 Ci/mmol. Using a filtration binding assay the Kd from receptor saturation analysis is 10–40 pM and there are 50,000–100,000 receptor sites per cell. These reagents have permitted the development of a reliable, reproducible and convenient drug screening assay, in kit format, for compounds acting at the C5a receptor.