Low or undetectable levels of surface high affinity cholera toxin receptors on normal hemopoietic growth...

The membrane monosialoganglioside GM1, the high affinity receptor for cholera toxin, is generally considered ubiquitous on normal cells. It was found to be abundant both on normal mature hemopoietic cells and on leukemic cells. By contrast, the normal factor-dependent cell lines, which achieve indefinite proliferation in the presence of the multilineage hemopoietic growth factor apparently displayed the unique character of having low or undetectable levels of surface membrane and cytoplasmic cholera toxin receptors. These results were obtained by the Scatchard analysis of 125iodinated toxin binding, immunofluorescence studies and gel electrophoresis autoradiography. This corroborated the fact that these cells were highly resistant to growth inhibition by cholera toxin (microM to fM) while normal mature cells and leukemic cells of similar phenotype were sensitive.