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PURPOSE: To demonstrate the detection of carcinoid tumor of the ovary by gamma probe during surgery in a patient in whom the exact location of a metastatic tumor was uncertain. METHODS: Twenty-four hours after injection of 350 MBq (9.5 mCi) I-123, an anterior image of the abdomen was acquired before surgery to demonstrate MIBG accumulation. Holding the ovary in the hand during the operation, a surgical gamma probe indicated the exact location of highest radioactivity. RESULTS/CONCLUSIONS: Intraoperative MIBG scanning is a useful noninvasive detection method to localize metastases of carcinoid in the ovary. This method should be used only when it is not clear where the area of increased activity is located in the body because there are certain costs involved.

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Substance P (SP) is a tachykinin involved in the regulation of inflammatory processes. Tachykinins bind to three subtypes of neurokinin (NK) receptors. However, recently we demonstrated that monocytes express a SP binding site that is not one of the known NK receptors. Activation of this SP receptor leads to the stimulation of MAP kinase in monocytes. In the present paper we show that this novel SP binding site is coupled to a GTP binding protein of the Gi alpha 1/2 subclass. Triggering of the SP receptor leads to a rapid rise in cytosolic calcium. In a more sustained way, SP stimulates phospholipase D (PLD) activity in human monocytes. The effects of SP on calcium, PLD, and MAP kinase activity can be blocked by pretreatment of the cells with pertussis toxin, which is in agreement with receptor coupling to Gi. At a functional level, stimulation of the non-NK SP receptor on monocytes results in the induction of IL-6 production. We show here that the order of potency for activation of monocytes by various ligands is directly related to the Ki for displacement of labeled SP by these ligands. Therefore, our data strongly suggest that the effects of SP are mediated via the novel SP receptor we recently described.

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In this paper we demonstrate several aspects of the mechanisms of action of the neurotransmitter Substance P in the immune system. We describe how Substance P can activate T cells, B cells, monocytes, and granulocytes to, respectively, proliferation, immunoglobulin synthesis, cytokine production, and chemotaxis. However, the neurotransmitter does not trigger cells of the immune system only via the well-characterized neurokinin-1 receptor, which mediates the signaling by Substance P in the neuroendocrine system. We show that Substance P can activate T cells receptor-independently. The receptor-independent activation of T cells leads to the activation of heterotrimeric G proteins and calcium-influx into the T cell, followed by an increase in proliferation of the cell. Apart from the receptor-independent activation pathway, Substance P can also activate monocytes and B cells via a nonneurokinin Substance P receptor. Activation of this novel receptor leads to the activation of MAP kinase, which is an important second messenger in the cascade leading to cytokine production by monocytes. In contrast to the non-neurokinin Substance P receptor, triggering of the NK-1 receptor, transfected in Jurkat cells, or triggering of T cells via receptor-independent pathways does not lead to activation of MAP kinase. Combining the data, we can conclude that the interaction between the neuroendocrine system and the immune system with regard to Substance P clearly indicates that the immune system does not necessarily mirror the communication pathways that are used in the neuroendocrine system. Substance P is capable of signaling the immune system via multiple activation pathways.

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The data presented in this paper demonstrate a new substance P (SP) binding site that is expressed on human monocytes. The apparent dissociation constant (Kd) for binding of 125I-labeled Bolton Hunter-SP (125I-BH-SP) to the receptor on monocyte membranes is 2.24 +/- 0.9 x 10(-7) M and the maximum binding capacity (Bmax) is 4.7 +/- 0.5 pmol/mg membrane protein. It could be excluded that this receptor is one of the known neurokinin (NK) type of receptors on the basis of binding characteristics for NK1, NK2, and NK3 agonists. Moreover, we demonstrate that the binding site is neither the bombesin receptor nor the serpin enzyme complex receptor nor the FMLP receptor. The order of potency for inhibition of 125I-BH-SP binding to the receptor on monocyte membranes is NK1 antagonist [D-Pro2,D-Trp7,9]SP > SP > NK3 agonist [MePhe7]SP > bombesin. Cross-linking studies with disuccinimidylsuberate, followed by SDS-PAGE analysis, revealed that 125I-BH-SP is specifically bound to a membrane protein with an apparent molecular mass of 47 kDa. At a functional level, SP induces the activation of MAP kinase in human monocytes. The ED50 for activation of MAP kinase positively correlated (r = 0.999, p < 0.0005) with the apparent affinity of the ligands applied in the 125I-BH-SP displacement studies. From these results, we conclude that this SP binding site on monocytes is a non-NK receptor protein that is functionally linked to the activation of MAP kinase.

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The neuropeptide substance P (SP) has been shown to play an important role as a mediator of neurogenic inflammation. Moreover, in vitro SP is capable of modulating the activity of lymphocytes, monocytes and polymorphonuclear cells. We have examined one of the early events that occur after addition of SP to human peripheral blood mononuclear cells (PBMC). Addition of 10(-6)-10(-4) M SP to human peripheral blood mononuclear cells results in a dose-dependent rise in intracellular calcium concentration as determined by FACS analysis. We show that the effect of SP cannot be attenuated by the SP receptor antagonist [D-Pro4,D-Trp7,9]-SP(4-11), indicating that the response is not mediated via a SP receptor. Amphiphilic peptides like SP appear to have the capacity to insert themselves into the cell membrane and interact directly with intracellular proteins. This hypothesis is supported by the fact that the amphiphilic analogue of SP, [D-Pro2,D-Phe7,D-Trp9]-SP, is capable of inducing a calcium response in our system, although it is known as an SP receptor antagonist. Functionally, we show that SP increases the proliferative response of T cells induced by suboptimal concentrations of the mitogen PHA. These data provide evidence of a potential role of SP in the regulation of lymphocyte activation.

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