The strategy required for the development of the immunochemical reagents needed for a non-competitive assay for the detection of haptens was investigated. For this work, these reagents were termed "anti-complex" antibodies. To preserve the integrity of such an assay, these "anti-complex" antibodies should not react with either the free anti-hapten antibody or the free hapten and they should not compete with the hapten for binding to the anti-hapten antibody. Anti-hapten hybridomas were developed using standard hybridoma technology. The development of anti-complex hybridomas was investigated using standard hybridoma technology and the novel approach of intrasplenic immunization. Both immunization protocols addressed the three questions concerning the strategy for developing such hybridomas, namely the type of immunization (snygeneic or allogeneic), the physico-chemical nature of the hapten in the complex (free or conjugated) and the physico-chemical nature of the anti-hapten antibody in the complex (intact or fragmented). (Abstract shortened with permission of author.)