NMB: a human neuroblastoma cell line with specific opiate binding sites

The human neuroblastoma cell line designated NMB (Brodeur et al., 1977, Cancer 40: 2256) has been shown to have specific opiate binding sites. These sites are highly stereospecific. Two characteristic delta specific peptides, D-Ala2-D-Leu5 enkephalin and D-Thr2-D-Thr6 enkephalin, have high affinity for the binding sites. Morphine binds specifically but with a much lower affinity. Dextrorphan and the mu specific peptide morphiceptin (Tyr-Pro-Phe-Pro-CO-NH2) do not bind to the site. The binding sites are heat and trypsin sensitive. Sodium ions specifically lower agonist binding to the sites. Approximately 14,000 binding sites per cell are found. The binding characteristics of these sites are very similar to those of the delta sites characterized on mouse neuroblastoma cell lines.