in vitro and in vivo detection of somatostatin receptors in human malignant lymphomas

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Abstract
A wide variety of primary and metastatic human neoplasms express somatostatin receptors (SS‐Rs). We evaluated the SS‐R status of malignant lymphomas that had been surgically removed from 31 patients, by use of in vitro SS‐R autoradiography with the SS analog 1251‐[Tyr3]‐octreotide as radioligand. Of 11 low‐grade‐malignancy B‐cell non‐Hodgkin's lymphomas, 10 were SS‐R‐positive, with a high receptor density restricted to the neoplastic follicles. All of the 8 intermediate‐grade lymphomas were SS‐R‐positive. Of the B‐cell lymphomas of high‐grade malignancy, 7 out of 10 were SS‐R‐positive, often with a high density of receptors. One T‐cell lymphoma and one Hodgkin's lymphoma were also positive. SS‐Rs were of high affinity (KD = 1.2 nM) and specific for bioactive SS analogs. In 4 patients, the lymphomas were localized in vivo by use of gamma‐camera scintigraphy after i.v. injection of the SS analog IIIIn‐[DTPA‐D‐Phe]‐octreotide. Hot spots, identified in all 4 patients, corresponded to SS‐R‐positive malignant‐lymphoma tissue, as confirmed by receptor autoradiography of the surgically removed tumors. Our data show that SS‐Rs are valuable pathobiochemical tissue markers and potentially useful in vivo diagnostic tools for human malignant lymphomas.