We have isolated the human cDNA homologue of a mouse helper T-cell-specific cDNA sequence, called P600, from an activated human T-cell cDNA library. The human cDNA encodes a secreted, mainly unglycosylated, protein with a relative molecular mass of -10,000. We show that the human and mouse proteins cause extensive morphological changes to human monocytes with an associated up-regulation of major histocompatibility complex class II antigens and the low-affinity receptor for immunoglobulin E (FcERII or CD23). In addition, they stimulate proliferation of human B cells that have been activated by anti-IgM antibodies or by anti-CD40 monoclonal antibodies presented by a mouse Ltk-cell line transfected with CDw32. Furthermore, the human protein induced considerable levels of IgM and IgG, but no IgA production, in cultures in which highly purified human surface IgD+ or total B cells were cocultured with an activated CD4+ T-cell clone. Based on these findings, we propose that this immunoregulatory protein be designated interleukin 13.

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Although mouse liver F4/80(+) Kupffer cells consist of cytokine-producing CD11b(+) cells and phagocytic CD68(+) cells, an undefined CD11b(-) CD68(-) subset (30%) also exists. We herein demonstrate a more fundamental classification by adding CD32 (FcγRII), which covers most liver F4/80(+) cells and the distinct functions of them. Among the F4/80(+) cells, 50%, 40%, and 30% of cells were CD32(+), CD68(+), and CD11b(+), respectively, and one-half of the CD68(+) cells coexpressed CD32. CD68(+) and CD32(+) cells, but not CD11b(+) cells, expressed a phagocytosis-related CRIg. Gy (6) irradiation depleted liver CD11b(+) cells and those in the spleen, bone marrow, and peripheral blood but not liver CD32/CD68(+) cells. Transfer of bone marrow cells into the irradiated mice reconstituted liver CD11b(+) cells. Conversely, clodronate pretreatment depleted only liver CD32/CD68(+) cells but not liver CD11b(+) cells and peripheral blood or spleen CD11b(+) monocytes/macrophages. Moreover, the CD32(+) cells might be precursors of CD68(+) cells, as a large proportion of CD32(+) cells expressed the c-kit (CD117), and CD34 and CD32(+) cells acquired CD68 immediately after bacteria administration. CD32/CD68(+) cells, but not CD11b(+) cells, expressed resident macrophage-specific MerTK and CD64 (FcγRI). Challenge with Staphylococcus aureus or liver metastatic EL-4 tumor cells indicated that the CD68(+) subset is engaged in systemic bactericidal activity, whereas the CD11b(+) subset is pivotal for liver antitumor immunity. Human liver CD14(+) Kupffer cells could also be classified into three similar subsets. These results suggest that liver CD68(+) Kupffer cells and CD11b(+) Kupffer cells/macrophages are developmentally and functionally distinct subsets.

Each metabotropic glutamate receptor possesses a large extracellular domain that consists of a sequence homologous to the bacterial periplasmic binding proteins and a cysteine-rich region. Previous experiments have proposed that the extracellular domain is responsible for ligand binding. However, it is currently unknown whether the extracellular ligand binding site can bind ligands without other domains of the receptor. We began by obtaining a sufficient amount of receptor protein on a baculovirus expression system. In addition to the transfer vector that encodes the entire coding region, transfer vectors that encode portions of the extracellular domain were designed. Here, we report a soluble metabotropic glutamate receptor that encodes only the extracellular domain and retains a ligand binding characteristic similar to that of the full-length receptor. The soluble receptor secreted into culture medium showed a dimerized form. Furthermore, we have succeeded in purifying it to homogeneity. Dose-response curves of agonists for the purified soluble receptor were examined. The effective concentration for half-maximal inhibition (IC 50 ) of quisqualate for the soluble receptor was 3.8 ؋ 10 ؊8 M, which was comparable to that for the full-length receptor. The rank order of inhibition of the agonists was quisqualate > > ibotenate > L-glutamate Ϸ (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid. These data demonstrate that a ligand binding event in metabotropic glutamate receptors can be dissociated from the membrane domain.Glutamate receptors are divided into two distinct classes: ionotropic glutamate receptors (iGluRs) 1 and metabotropic glutamate receptors (mGluRs) (1, 2). The iGluRs consist of Nmethyl-D-aspartate receptors and non-N-methyl-D-aspartate receptors. Non-N-methyl-D-aspartate receptors are further subdivided into two groups: ␣-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors and kainate receptors. iGluRs are ligand-gated ion channels that transduce glutamate binding into cation influx. mGluRs that have been discovered most recently comprise eight subtypes, which are divided into three groups according to agonist selectivity, coupling to different effector systems, and sequence homology (3-6). Group I includes mGluR1 and mGluR5, which are coupled to inositol phospholipid metabolism. Group II (mGluR2 and mGluR3) and group III (mGluR4, mGluR6, mGluR7, and mGluR8) are negatively coupled to adenylate cyclase activity. Functional analyses of these mGluRs are now avidly being performed. The evidence is accumulating that mGluRs modulate excitatory synaptic transmission (7) through various neural transduction pathways, such as regulation of neurotransmitter release (8), influences on ion channel activity (9), and modulation of synaptic plasticity (10).mGluRs have a remarkably large extracellular domain that has no homology with the other G protein-coupled receptors (GPCRs) except Ca 2ϩ -sensing receptors (11). Previous experiments (12, 13) have proposed that the ligand binding site resides mainly in t...

Adenosine is a key myocardial metabolite that elicits coronary vasodilation in a variety of pathophysiological conditions. We examined the mechanism of adenosine-induced vasodilation in coronary arterioles from patients with heart disease. Human coronary arterioles (HCAs) were dissected from pieces of the atrial appendage obtained at the time of cardiac surgery and cannulated for the measurement of internal diameter with videomicroscopy. Adenosine-induced vasodilation was not inhibited by endothelial denudation, but A(2) receptor antagonism with 3,7-dimethyl-1-propargylxanthine and adenylate cyclase (AC) inhibition with SQ22536 significantly attenuated the dilation. In contrast, A(1) receptor antagonism with 8-cyclopentyl-1,3-dipropylxanthine significantly augmented the sensitivity to adenosine. Moreover, dilation to A(2a) receptor activation with 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethylcarboxamido-adenosine hydrochloride was reduced by the A(1) receptor agonist (2S)-N(6)-(2-endo-norbornyl)adenosine. The nonspecific calcium-activated potassium (K(Ca)) channel blocker tetrabutylammonium attenuated adenosine-induced dilation, as did the intermediate-conductance K(Ca) blocker clotrimazole. Neither the large-conductance K(Ca) blocker iberiotoxin nor small-conductance K(Ca) blocker apamin altered the dilation. In conclusion, adenosine endothelium independently dilates HCAs from patients with heart disease through a receptor-mediated mechanism that involves the activation of intermediate-conductance K(Ca) channels via an AC signaling pathway. The roles of A(1) and A(2) receptor subtypes are opposing, with the former being inhibitory to AC-mediated dilator actions of the latter. These observations identify unique fundamental physiological characteristics of the human coronary circulation and may help to target the use of novel adenosine analogs for vasodilation in perfusion imaging or suggest new strategies for myocardial preconditioning.

The three‐dimensional structures of some components of snake venoms forming so‐called ‘three‐fingered protein’ domains (TFPDs) are similar to those of the ectodomains of activin, bone morphogenetic protein and transforming growth factor‐β receptors, and to a variety of proteins encoded by the Ly6 and Plaur genes. The analysis of sequences of diverse snake toxins, various ectodomains of the receptors that bind activin and other cytokines, and numerous gene products encoded by the Ly6 and Plaur families of genes has revealed that they differ considerably from each other. The sequences of TFPDs may consist of up to six disulfide bonds, three of which have the same highly conserved topology. These three disulfide bridges and an asparagine residue in the C‐terminal part of TFPDs are essential for the TFPD‐like fold. Analyses of the three‐dimensional structures of diverse TFPDs have revealed that the three highly conserved disulfides impose a major stabilizing contribution to the TFPD‐like fold, in both TFPDs contained in some snake venoms and ectodomains of several cellular receptors, whereas the three remaining disulfide bonds impose specific geometrical constraints in the three fingers of some TFPDs.

To understand the mechanisms involved in immunological tolerance to skin-associated antigens, we have developed transgenic (Tg) mice that express a model self-antigen, membrane-bound chicken ovalbumin (OVA), under the control of a keratin 14 (K14) promoter. K14-mOVA Tg mice express OVA mRNA in the epidermis, and appear normal. K14-mOVA Tg mice failed to mount T cell and delayed type hypersensitivity reactions to OVA, suggesting that the Tg mice were tolerant to OVA. Skin dendritic cells, including Langerhans cells, may contribute to the tolerance induction because migratory skin DC derived from K14-mOVA efficiently activated CD8(+) T cells from OVA-specific T-cell receptor (Va2/Vb5) Tg (OT-I) mice. OT-I cells expanded and accumulated in skin-draining lymph nodes after intravenous injected into K14-mOVA mice and exhibited activation markers. Graft-versus-host disease-like skin lesions appeared in K14-mOVA mice by day 7 after injection of OT-I cells. These studies demonstrate that K14-mOVA Tg mice are susceptible to an autoimmunelike skin disease induced by passively transferred naïve CD8(+) OVA T-cell receptor Tg T cells, and serve as a good model for understanding self-tolerance and for the investigation of the pathogenesis, treatment and potential prevention of cell-mediated autoimmune reactions in skin.

Background-Vascular abnormalities are a major cause of postoperative complications in irradiated tissues. Endothelial cell dysfunction characterized by diminished endothelium-dependent relaxation may be involved. We examined the endothelium-dependent relaxation and morphology of the endothelium in irradiated human cervical arteries. Methods and Results-Irradiated arteries were taken from the neck region of patients who had radiation therapy. Arteries from patients who did not receive radiation therapy were used as controls. Endothelium-dependent relaxation to acetylcholine and A23187 was impaired in irradiated arteries. Norepinephrine-induced contraction and sodium nitroprusside-induced relaxation were unchanged. In control arteries, N