The cytoplasm of myeloma cells is rich in ribose nucleic acid. The basophilic inclusion bodies which develop in myeloma cells under the influence of stilbamidine contain ribose nucleic acid. The myeloma tissue of patients treated with stilbamidine contains appreciable amounts of stilbamidine.
There is reason to believe that the nucleoproteins of myeloma cells differ from the nucleoproteins of other cells. This could explain why stilbamidine reacts with the nucleoproteins of myeloma cells only, and not with the nucleoproteins of other cells.