Tamm-Horsfall protein (THP) is the major glycoprotein component of urine, yet its biological role remains obscure. Recent reports have suggested that a concanavalin A (Con A)-binding fraction of THP from pregnancy urine can bind the cytokines tumour necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1). In order to investigate this claim in relation to THP from normal adult urine we raised monoclonal antibodies to THP and sought THP/TNF-alpha interactions in three separate assay systems. We found no evidence that THP binds to TNF-alpha under physiological conditions, but we observed that it exerts a weak, probably not physiologically relevant, but reproducible inhibitory effect on the toxicity of TNF-alpha for monolayers of L929 cells, even when the cells are pretreated with the THP, and washed before addition of the cytokine. Since our preparations of THP do not interact directly with TNF-alpha we postulated an interaction with the cells themselves, or with their extracellular matrix. The THP was found by ELISA, immunoblotting and immunohistology, to bind to as yet unidentified components of the extracellular matrix in a manner dependent on cations, pH and carbohydrates. These data, considered in the light of the published amino acid sequence and biochemical properties, suggest that THP is a member of a structural glycoprotein family known to modulate cell adhesion. 相似文献
A plasma HIV-1 RNA amplification assay (RNA assay), a quantitative peripheral blood mononuclear cell (PBMC) microculture (culture), and a PBMC HIV-1 DNA amplification assay (DNA assay) were compared for diagnosis of HIV-1 infection in infants receiving zidovudine in Pediatric AIDS Clinical Trials Group protocol 185; assays were performed for all 24 infected and 100 uninfected infants. HIV-1 infection was defined as >or=2 positive cultures or positive antibody to HIV-1 at >or=18 months. Cultures were performed at birth and 6 and 24 weeks of age; DNA and RNA assays were performed on cryopreserved specimens. The sensitivity of culture and DNA and RNA assays at birth was 20.8%, 10.5%, and 26.7%, respectively. At older ages, sensitivity typically exceeded 80%, remaining highest for the RNA assay (>85%). Assay specificity was >99%. Positive predictive values exceeded 93% for each assay at each age; negative predictive values were highest (>90%) for the RNA assay. At birth (P < 0.005) and age 6 weeks (P < 0.001), a significantly larger proportion of infected infants were identified by means of the RNA assay than by the other assays. The diagnostic performance of the RNA assay matched or exceeded that of culture and the DNA assay. Given that RNA assays require less blood volume and yield rapid results, our study adds to existing data suggesting that RNA assays may be used for early diagnosis of HIV-1 infection in infants. 相似文献
The occurrence of immune complexes in the serum and the level of the C3 breakdown product C3d in the plasma from patients with leprosy were studied by quantitative methods and the results were compared in various forms of the disease. These studies were performed on sixty-two samples from twenty-six patients. The serum 125I-C1q binding activity was found to be increased by more than 2 s.d., as compared to the normal values, in most of the sera from patients with erythema nodosum leprosum (ENL) (80%) and uncomplicated lepromatous leprosy (82%), but also in the sera from patients with tuberculoid leprosy (58%). In vitro studies suggested that immune complexes involving mycobacterial antigens were present in leprosy sera. An increased C3d level (greater than 2s.d.) was also found in most of the plasma from patients with ENL (70%), but rarely in the plasma from patients with uncomplicated lepromatous leprosy (18%) and never in tuberculoid leprosy patients' plasma. The absence of a significant correlation between the 125I-C1q binding activity and the C3d level in leprosy patients may suggest that extravascular immune complexes are involved in the complement activation occurring in ENL. The quantitation of C3d in plasma may be of some practical interest in the early diagnosis of ENL complications of leprosy. 相似文献
Angiogenesis inhibitors are receiving increased attention as cancer therapeutics, but little is known of the cellular effects of these inhibitors on tumor vessels. We sought to determine whether two agents, AG013736 and VEGF-Trap, that inhibit vascular endothelial growth factor (VEGF) signaling, merely stop angiogenesis or cause regression of existing tumor vessels. Here, we report that treatment with these inhibitors caused robust and early changes in endothelial cells, pericytes, and basement membrane of vessels in spontaneous islet-cell tumors of RIP-Tag2 transgenic mice and in subcutaneously implanted Lewis lung carcinomas. Strikingly, within 24 hours, endothelial fenestrations in RIP-Tag2 tumors disappeared, vascular sprouting was suppressed, and patency and blood flow ceased in some vessels. By 7 days, vascular density decreased more than 70%, and VEGFR-2 and VEGFR-3 expression was reduced in surviving endothelial cells. Vessels in Lewis lung tumors, which lacked endothelial fenestrations, showed less regression. In both tumors, pericytes did not degenerate to the same extent as endothelial cells, and those on surviving tumor vessels acquired a more normal phenotype. Vascular basement membrane persisted after endothelial cells degenerated, providing a ghost-like record of pretreatment vessel number and location and a potential scaffold for vessel regrowth. The potent anti-vascular action observed is evidence that VEGF signaling inhibitors do more than stop angiogenesis. Early loss of endothelial fenestrations in RIP-Tag2 tumors is a clue that vessel phenotype may be predictive of exceptional sensitivity to these inhibitors. 相似文献
Bovine conglutinin was used in a solid-phase assay for the detection of immune complexes. In a first step, the tested serum sample is incubated in polypropylene tubes coated with conglutinin to allow C3-coated immune complexes to bind to solid-phase conglutinin. In a second step, the conglutinin-bound complexes are detected using an enzyme-conjugated or radiolabelled anti-immunoglobulin antibody.
The conglutinin-binding (KgB) test does not suffer from the interference of DNA, heparin or endotoxins. Its limit of sensitivity for aggregated IgG is 3 μg/ml undiluted human serum. Immune complexes prepared in vitro using tetanus toxoid, or DNA, and corresponding antibodies in human sera could be detected at various antigen/antibody ratios and at antibody concentrations lower than 8 μg/ml. The KgB test allowed for the detection of immune complexes in sera from patients with systemic lupus erythematosus, rheumatoid arthritis, idiopathic vasculitis, leprosy and leukemia. These sera were also tested using the 125I-labelled Clq-binding activity (BA) test and the KgB test simultaneously, and a significant rank order correlation was observed. In patients with leukemia, a significant correlation was observed using three tests, KgB, 125I-labelled Clq BA and Raji-cell radioimmunoassay (RIA).
Therefore, the KgB test appears as a simple and reproducible method, utilizing a very stable reagent, with a sensitivity and specificity comparable to the other tests studied and allowing for clinical application.
The proteins of respiratory syncytial (RS) virus were analyzed by SDS-polyacrylamide gel electrophoresis. Eight virion structural proteins with molecular weights of 180,000, 89,000, 48,000, 42,000, 34,000, 28,000, 25,000, and 21,000 were identified. These proteins were given tentative designations of L (180,000), G (89,000), F1 (48,000), NP (42,000), P (34,000), M (28,000), Vp25 (25,000), and F2 (21,000). The 89,000-, 48,000-, and 21,000-dalton polypeptides were glycosylated and could be purified on lentil-lectin sepharose columns. All three glycoproteins could be immunoprecipitated from extracts of infected cells but not from uninfected cells, suggesting that they are viral specified. The host cell affected the apparent molecular weights of the largest and smallest glycosylated polypeptides possibly by differences in glycosylation. The 48,000- and 21,000-dalton glycopolypeptides were disulfide linked subunits of a 68,000-dalton glycoprotein that was seen on unreduced gels. The 68,000-dalton glycoprotein was thus similar to the fusion (F) protein of paramyxoviruses. Treatment of infected cultures with tunicamycin, a drug that blocks glycosylation, inhibited syncytial formation and resulted in over a 1000-fold reduction of extracellular infectious virus. Virions purified from tunicamycin-treated cells had reduced amounts of all three glycosylated proteins. No new forms of these proteins were conclusively identified, suggesting that unglycosylated forms of RS glycoproteins were not incorporated into virion membranes. 相似文献
Distinct differences in the extent and progression of the lateral and epicardial boundaries of evolving regional infarcts were demonstrated in isolated rabbit hearts. Ischemia was produced by interrupting (0-240 minutes) flow in the ventral interventricular branch of the left coronary artery, whilst the remainder of the heart was continuously perfused with oxygenated Krebs-Henseleit bicarbonate buffer. Perfusion fixed blocks were freeze-fractured then examined using back-scattered electron imaging in a scanning electron microscope. Control myocytes showed relatively smooth, continuous internal fracture faces. After 30 min of ischemia myocytes showed evidence of mild, probably reversible, injury in the form of prominence of pits and channels. Severe injury, characterized by separation of organelles and prominent intracellular spaces, developed after 60 or more min of ischemia, first in the subendocardial two thirds, and after 120 min across the full thickness of the ventricular wall. At the lateral margins of infarcts there was a distinct cell-to-cell boundary between control and severely injured myocytes, with only a few scattered mildly injured cells within 30 mu of the infarct. Although transmural progression of necrosis provides the potential for recovery of the external aspect of the myocardium in the ischemic zone by reperfusion, corresponding regions of salvageable myocytes at lateral infarct margins are very narrow. 相似文献
PROBLEM: During normal pregnancy, major changes occur in the production of Th2/Th1 cytokines at the feto-maternal interface. Th2 cytokines such as interleukin-4 (IL-4) or interleukin-10 (IL-10) are predominantly produced locally in the uterine and placental tissues, whereas the production of Th1 cytokines such as tumor necrosis factor alpha (TNF-α) and interferon gamma (IFN-γ) are decreased. Because these modulations might be induced by the embryo, the current study was carried out to test the effect of rabbit blastocoelic fluid on the production of Th2/Th1 cytokines by lymphocytes, and to investiate the possible implication of transforming growth factor β2 (TGF-β2) prostaglandin E2 (PGE2) as modulators of the production of these cytokines. METHOD OF STUDY: Human peripheral blood lymphocytes (PBL) were cultured along with ConcanavalinA (Con A), and rabbit blastocoelic fluid was collected on day 12 of gestation (BF d-12). Concentrations of cytokines in culture media were determined by enzyme-linked immunoadsorbent assay (ELISA). RESULTS: Addition of BF d-12 in the culture medium induced a strong inhibition of IL-2, TNF-α, IL-10, and granulocyte-macrophage colony-stimulating factor (GM-CSF) production. However, an initial pretreatment of the lymphocytes with BF d-12, followed by a Con A stimulation, led to a marked increase in GM-CSF production, whereas IL-2, TNF-α, and IL-10 secretions were inhibited. It was also demonstrated, for the first time, that a pretreatment of the lymphocytes with TGF-β2 and PGE2 increased GM-CSF production to the same level reached after the addition of BF d-12. Furthermore, removal of TGF-β2 and PGE2 from BF d-12 by affinity chromatography reduced the effect of BF d-12 on GM-CSF production. CONCLUSIONS: Taken together, these findings suggest that the embryo, in modulating harmful and beneficial cytokine production locally, plays an active role in its protection against maternal immune cellular assault. These results also emphasize the importance of growth factors for successfully maintaining pregnancy. 相似文献
'Cancer immunoediting' is a process wherein the immune system protects hosts against tumor development and facilitates outgrowth of tumors with reduced immunogenicity. Although interferon-gamma (IFN-gamma) is known to be involved in this process, the involvement of type I interferons (IFN-alpha/beta) has not been elucidated. We now show that, like IFN-gamma, endogenously produced IFN-alpha/beta was required for the prevention of the growth of primary carcinogen-induced and transplantable tumors. Although tumor cells are important IFN-gamma targets, they are not functionally relevant sites of the actions of the type I interferons. Instead, host hematopoietic cells are critical IFN-alpha/beta targets during development of protective antitumor responses. Therefore, type I interferons are important components of the cancer immunoediting process and function in a way that does not completely overlap the functions of IFN-gamma. 相似文献