A comparison of the expression of the DIDS-binding proteins from normal and tumorigenic human cells

A monoclonal antibody was prepared against DIDS, an inhibitor of anion transport, and used to compare the occurrence and distribution of DIDS-binding sites of tumorigenic and non-tumorigenic human somatic-cell hybrids. The monoclonal antibody (E8) was produced by the fusion of the mouse myeloma (NS-1) with mouse spleen cells and is of the IgG1 subclass. The apparent half-saturation of DIDS for HEp-2 cells is 16 microM and the reaction is rapid. The number of binding sites on tumorigenic and non-tumorigenic hybrid cells was the same. The DIDS-binding protein occurs homogeneously on all cells, a characteristic which distinguishes it from the possible tumour antigen recognised by the M/27 monoclonal antibody.