The specific inhibition of cellular clonogenic proliferation using 211At labelled lectins and antibodies--I

A monoclonal antibody with a broad anti-human leucocyte specificity, designated BK 19.45 and the plant lectin Concanavalin A have been labelled with the alpha-emitting cyclotron produced radiohalogen astatine-211. Both human and murine tumour cell lines and human leukemic bone marrow samples have been specifically labelled with these radioactive proteins. In all cases the amount of 211At bound to the cells is directly correlated with a decrease in cellular reproductive potential as shown by the ability of the cells to proliferate in a clonogenic assay. For the labelled monoclonal antibody experiments, the radiation dose needed to yield 37% cell survival, the D37 dose, may be achieved with an average of 12 211At atoms/cell.