Simple solid-phase radioimmunoassay for human leukemia-associated cell membrane antigens

In the present study, a simple solid-phase radioimmunoassay was developed to determine detergent-extracted human leukemia-associated cell membrane antigens. In the assay, 96-well microtiter plates are coated with human leukemia cell membrane antigens containing a T cell leukemia or a non-T cell leukemia antigen in the presence of a detergent, and treated with 1.6% bovine serum albumin solution. The coated antigens were reacted with an appropriate murine monoclonal antibody (mAb), i.e., SN2 or SN3, which defines a T leukemia antigen or a non-T leukemia antigen, respectively. The bound mAb is determined by a second reaction with 125I-labeled F(ab')2 of goat anti-mouse Ig. The effect of the following detergents on the assay was investigated: Nonidet P-40 (NP-40), Renex 30, deoxycholate, 3-(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate (CHAPS) and taurocholate. The best antigen dose-dependent antibody binding results were obtained using the plates coated with antigens in the presence of taurocholate, a rarely used detergent, whereas no significant antibody binding was observed in the assays using 2 nonionic detergents, i.e., NP-40 and Renex 30. In addition, the usefulness of the present assay with taurocholate during the purification of the antigens was demonstrated. It is very likely that the present solid-phase radioimmunoassay using taurocholate will also be useful in determining other non-leukemia cell membrane antigens.