Although active oxygen species play important roles in the pathogenesis of various diseases, the molecular mechanism for oxygen toxicity in vascular diseases remains to be elucidated. Since endothelium-derived relaxing factor (EDRF) is inactivated by superoxide radicals in vitro, oxidative stress in and around vascular endothelial cells may affect the circulatory status of animals. To study the role of superoxide radicals and related enzymes, such as superoxide dismutase (SOD), in vascular diseases, we have developed a fusion protein (HB-SOD) consisting of human Cu/Zn-type SOD and a C-terminal basic peptide with high affinity for heparan sulfate on endothelial cells. When injected intravenously, BB-SOD bound to vascular endothelial cells, underwent transcellular transport, and localized within vascular walls by a heparininhibitable mechanism. The blood pressure of spontaneously hypertensive rats (SHR) but not normal animals was decreased significantly by HB-SOD. Heparin inhibited the depressor effect of HB-SOD. In contrast, native SOD had no effect on blood pressure of either SHR or normal rats. Neither H202-inactivated HB-SOD nor the C-terminal heparin-binding peptide showed such a depressor effect, suggesting that the catalytic function of HB-SOD is responsible for its depressor action. To know the source of superoxide radicals, we determined xanthine oxidase activity in the aorta and uric acid levels in the plasma. Although no appreciable difference in xanthine oxidase activity was found between the two animal groups, uric acid levels were significantly higher in SHR than in normal rats. Oxypurinol, a potent inhibitor of xanthine oxidase, also decreased the blood pressure of SHR but not of normal rats. These rmdings indicate that superoxide radicals in and around vascular endothelial cells play critical roles in the pathogenesis of hypertension of SHR.Reactive oxygen species play critical roles in the pathogenesis of various diseases, such as cardiovascular injury associated with circulatory disturbance (1, 2). Many factors, such as endothelin and endothelium-derived relaxing factor (EDRF), affect the circulatory status of animals by modulating vascular resistance. Nitric oxide (NO) and NOgenerated compounds account for the biological actions of EDRF (3, 4). EDRF is synthesized predominantly in vascular endothelial cells and is transferred to smooth muscle cells, where it facilitates cGMP generation leading to vasodilatation. Superoxide radicals can inactivate NO and, hence, EDRF-dependent relaxation of aortic rings and endotheliumdenuded aortas was enhanced by Cu/Zn-type superoxide dismutpse (SOD) (5, 6). Based on such in vitro experiments, superoxide radicals have been postulated to affect vascular resistai e by inactivating EDRF. Since intravenously injected eu/Zn-SOD lacks tissue-specific localization and disappears rapidly from the circulation, predom'iantly due to The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marjceq "ad...

Recruitment of dendritic cells (DCs) to lymph nodes (LNs) is pivotal to the establishment of immune response. Whereas DCs have been proven to undergo afferent lymphatic pathway to enter LNs from peripheral tissues, a question remains if DCs also migrate into LNs directly from the circulation. Here we demonstrate that plasmacytoid DC (pDC) precursors can transmigrate across high endothelial venules (HEVs) of inflamed LNs in mice. Bacterial infection induces a significant number of pDC and myeloid DC (mDC) precursors into the circulation. Both subsets express a common set of chemokine receptors except CXCR3, display parallel mobilization into the blood, but show distinct trafficking pathway to the LNs. In a short-term homing assay, whereas mDC precursors migrate to peripheral tissues and subsequently to draining LNs, pDC precursors directly enter the LNs in a CXCL9 and E-selectin dependent manner. Tumor necrosis factor-alpha controls not only DC precursor mobilization into the blood but also chemokine up-regulation on LN HEVs. A similar trafficking pathway is observed also in viral infection, and CXCR3(-/-) mice-derived pDC precursors show defective trans-HEV migration. This study clarifies the inflammation-dependent, chemokine-driven distinct property of DC precursor trafficking.

We have studied the recruitment and roles of distinct dendritic cell (DC) precursors from the circulation into Propionibacterium acnes–induced granulomas in mouse liver. During infection, F4/80−B220−CD11c+ DC precursors appeared in the circulation, migrated into the perisinusoidal space, and matured within newly formed granulomas. Recruited DCs later migrated to the portal area to interact with T cells in what we term “portal tract–associated lymphoid tissue” (PALT). Macrophage inflammatory protein 1α attracted blood DC precursors to the sinusoidal granuloma, whereas secondary lymphoid organ chemokine (SLC) attracted mature DCs to the newly identified PALT. Anti-SLC antibody diminished PALT expansion while exacerbating granuloma formation. Therefore, circulating DC precursors can migrate into a solid organ like liver, and participate in the granulomatous reaction in response to specific chemokines.

Antiviral cell–mediated immunity is initiated by the dendritic cell (DC) network in lymph nodes (LNs). Plasmacytoid DCs (pDCs) are known to migrate to inflamed LNs and produce interferon (IFN)-α, but their other roles in antiviral T cell immunity are unclear. We report that LN-recruited pDCs are activated to create local immune fields that generate antiviral cytotoxic T lymphocytes (CTLs) in association with LNDCs, in a model of cutaneous herpes simplex virus (HSV) infection. Although pDCs alone failed to induce CTLs, in vivo depletion of pDCs impaired CTL-mediated virus eradication. LNDCs from pDC-depleted mice showed impaired cluster formation with T cells and antigen presentation to prime CTLs. Transferring circulating pDC precursors from wild-type, but not CXCR3-deficient, mice to pDC-depleted mice restored CTL induction by impaired LNDCs. In vitro co-culture experiments revealed that pDCs provided help signals that recovered impaired LNDCs in a CD2- and CD40L-dependent manner. pDC-derived IFN-α further stimulated the recovered LNDCs to induce CTLs. Therefore, the help provided by pDCs for LNDCs in primary immune responses seems to be pivotal to optimally inducing anti-HSV CTLs.

SummaryInitiation of an adaptive immune response against pathogenic organisms, such as bacteria and fungi, may involve phagocytic activity of dendritic cells (DC) or their immature precursors as a prelude to antigen processing and presentation. After intravenous injection of rats with particulate matter, particle-hden cells were detected in the peripheral hepatic lymph. Since it has been known there is a constant efflux of DC from nonlymphoid organs into the draining peripheral lymph, we examined whether these particle-laden cells belonged to the DC or macrophage lineage. The majority ofparticle-hden cells in lymph showed immature monocyte-like cytology, and the amount of ingested particles was small relative to typical macrophages. We identified these particle-laden cells as DC based on a number of established criteria: (a) they had a phenotype characteristic of rat DC, that is, major histocompatibility complex class I hish+ and IlhiO +, intercellular adhesion molecule 1 + and "80~ positive with the rat DC-specific mAb OX62; (b) they showed strong s~ulating capacity in primary allogeneic mixed leukocyte reaction; (c) in vitro, they had little phagocytic activity; and (d) the kinetics of translocation was similar to that of lymph DC in that they migrated to the thymus-dependent area of the regional nodes. Furthermore, bromodeoxyuridine feeding studies revealed that most of the particleladen DC were recently produced by the terminal division of precursor cells, at least 45% of them being <5.5 d old. The partide-hden DC, defined as OX62 + htex-hden cells, were first found in the sinusoidal area of the liver, in the liver peffusate, and in spleen cell suspensions, suggesting that the site of particle capture was mainly in the blood marginating pool. It is conduded that the particle-laden cells in the hepatic lymph are recently produced immature DC that manifest a temporary phagocytic activity for intravascular par'tides during or after the terminal division and that the phagocytic activity is downregulated at a migratory stage when they translocate from the sinusoidal area to the hepatic lymph.

Erythropoiesis occurs in erythroblastic islands, where developing erythroblasts closely interact with macrophages. The adhesion molecules that govern macrophage-erythroblast contact have only been partially defined. Our previous work has implicated the rat ED2 antigen, which is highly expressed on the surface of macrophages in erythroblastic islands, in erythroblast binding. In particular, the monoclonal antibody ED2 was found to inhibit erythroblast binding to bone marrow macrophages. Here, we identify the ED2 antigen as the rat CD163 surface glycoprotein, a member of the group B scavenger receptor cysteine-rich (SRCR) family that has previously been shown to function as a receptor for hemoglobinhaptoglobin (Hb-Hp) complexes and is believed to contribute to the clearance of free hemoglobin. CD163 transfectants and recombinant protein containing the extracellular domain of CD163 supported the adhesion of erythroblastic cells. Furthermore, we identified a 13-amino acid motif (CD163p2) corresponding to a putative interaction site within the second scavenger receptor domain of CD163 that could mediate erythroblast binding. Finally, CD163p2 promoted erythroid expansion in vitro, suggesting that it enhanced erythroid proliferation and/or survival, but did not affect differentiation. These findings identify CD163 on macrophages as an adhesion receptor for erythroblasts in erythroblastic islands, and suggest a regulatory role for CD163 during erythropoiesis. IntroductionThe functional unit for definitive erythropoiesis in the bone marrow is the erythroblastic island, a multicellular structure composed of a central macrophage surrounded by erythroblasts at various stages of differentiation. [1][2][3] The contact between erythroblasts and macrophages supports the growth, survival, and differentiation of erythroblasts, and allows for phagocytosis of the extruded erythroid nucleus. Thus far, the molecular interaction(s) that mediate the formation of erythroblastic islands have only been partly defined. 2,4 First, interactions between vascular cell adhesion molecule-1 (VCAM-1) on macrophages and ␣ 4 integrins on erythroblasts have been implicated in the contact between these cells. 5 Furthermore, a molecule called erythroblast macrophage protein (Emp) has been identified, which is expressed on macrophages, erythroblasts, and other cells. [6][7][8] Emp is believed to mediate erythroblast adhesion to macrophages, probably by homophilic interaction. Of relevance, Emp-deficient fetuses, which die perinatally, have significantly reduced numbers of erythroblastic islands and defective erythropoiesis. This phenotype appears to result from a deficiency in both macrophage development as well as disturbed erythroblast nuclear extrusion. Finally, the erythroid intercellular adhesion molecule-4 (ICAM-4) has been demonstrated to bind to the ␣ v integrin expressed by macrophages in erythroblastic islands, and this has also been shown to contribute to erythroblastic island formation in vivo. 9,10 We have previously identified the rat mac...

The migration pathways for dendritic cells (DC) from the blood are not yet completely resolved. In our previous study, a selective recruitment of DC progenitors from the blood to the liver was suggested. To clarify the role of the hepatic sinusoids in the migration of blood DC, relatively immature DC and mature DC were isolated from hepatic and intestinal lymph, and intravenously transferred to allogeneic hosts. It was then possible to detect small numbers of DC within secondary lymphoid tissues either by immunostaining for donor type major histocompatibility complex class I antigen or, at much higher sensitivity, for bromodeoxyuridine incorporated by proliferating cells (mainly T lymphocytes), which responded to the alloantigen presented by the administered DC. The intravenously injected DC accumulated in the paracortex of regional lymph nodes of the liver via a lymph-borne pathway. Intravenously injected fluorochrome-labeled syngeneic DC behaved similarly. In contrast, very few DC were found in spleen sections and were hardly detectable in other lymph nodes or in other tissues. An in situ cell binding assay revealed a significant and selective binding of DC to Kupffer cells in liver cryosections. It is concluded that rat DC can undergo a blood–lymph translocation via the hepatic sinusoids, but not via the high endothelial venules of lymph nodes. Hence the hepatic sinusoids may act as a biological concentrator of blood DC into the regional hepatic nodes. Kupffer cells may play an important role in this mechanism.

Clinical and laboratory features suggest that ataxic Guillain-Barré syndrome and acute sensory ataxic neuropathy form a continuous spectrum. The two conditions could be comprehensively referred to as 'acute ataxic neuropathy (without ophthalmoplegia)' to avoid nosological confusion because Fisher syndrome is not classified by the absence or presence of sensory ataxia. That is, acute ataxic neuropathy can be positioned as an incomplete form of Fisher syndrome.