Abstract: Derivatives comprising two hydrophilic haptens and an effector group comprising a radioactive isotope or known to be able to be labelled by a radioactive isotope or comprising an active principle or known to be able to bind an active principle, linked by a connecting bridge application to diagnosis and to therapeutics, diagnostic or therapeutic kits and immunological reagents containing them.

Abstract: Immunological reagents, consisting of a) antibody or fragment conjugates having both an anti-cell specificity and an anti-hapten specificity, and b) synthetic tracers containing at least two hapten sites and at least one site suitable to attach radioactive isotopes, paramagnetic ions, drugs or toxins, are provided. These reagents are capable of binding to target cells in a specific way, and the tracer localizes preferentially on the membrane of antigen-bearing cells, even in the presence of excess antibody conjugate (affinity enhancement). These reagents are usefully employed, either in vitro or in vivo, to detect tumors, metastases, or other tissue injuries, when the synthetic tracer carries radioactive or paramagnetic compounds, and to kill target cells when the synthetic tracer carries radioactive compounds or drugs or toxins.