[Somatostatin receptors in immune system cells]

Many hormones and some neuropeptides and neurotransmitters play a key role in regulating numerous lymphoid cell functions. In particular, somatostatin (ss), substance P (sp) and vasoactive intestinal polypeptide (vip) appear to be involved in numerous regulating mechanisms of cell activities in the immune system under both physiological and pathological conditions. ss may be produced by lymphoid cells and accessories as part of the immune system. The distribution of somatostatin receptors (ssr) in the normal human thymus has prompted the hypothesis that ss, and probably other neuropeptides, may play an important role in cell homeostasis in this organ, as well as being one of the processes that regulates the maturation of T lymphocytes. The advent of molecular biology has showed a variable expression of ssr on the various T and B cell lines or lines deriving from lymphoma/ leukemia and human myeloma. Using autoradiographic studies, ssr have been predominantly found in lymphoblastic areas of lymphoma, which represent the active part of the tumour. The expression of ssR has been found in vivo and in vitro, also in pathological sites in patients with autoimmune and granulomatous diseases like rheumatoid arthritis and sarcoidosis.