摘要:

Several reports have described polyclonal activation in mice acutely infected withTrypanosoma cruzi. The aim of this work was to analyse the participation of oneT. cruziantigenic fraction in this immunological event. The antigen selected was FI, an antigenic fraction of pI 7–9 obtained fromT. cruzicytosol separated by isoelectricfocusing. FI is constituted by molecules with molecular weights of around 60 and 20 KDa. The authors assayed the ability of this antigenic fraction to induce polyclonal activation of spleen mononuclear cells from normal (NSMC) BALB/c mice. NSMC showed a marked lymphoproliferative response measured by3H‐thymidine incorporation after 3 days of culture in presence of FI. The values reached by FI‐stimulated cells were 10 times higher than the controls (non‐stimulated cells). This effect was dose‐dependent. Furthermore, the authors observed that a purified T‐cell population in the presence of adherent cells was unaffected by FI. Additionally, in a culture of NSMC, FI stimulated the proliferation of B cells as observed by the increase of the percentage of B220+cells determined by FACS using FITC‐conjugated anti‐mouse B220. The authors noticed that the percentage of B220+Ly1+(CD5) populations in the presence of FI did not change with respect to the control (non‐stimulated cells), indicating that FI expanded both conventional and CD5+B cells. The isotypic pattern of the antibodies produced after 6 days of culture of NSMC in the presence of FI was predominantly IgM, which reacted with highly conserved antigens such as actin, myosin, myoglobin, thyroglobulin and carbonic anhydrase, but did not react with FI. A slight increase of IgG1 and IgG3 with respect to the control was observed but no changes on the levels of IgG2 was noticed. These results indicate that FI promotes activation, proliferation and differentiation in antibody‐secreting cells of normal

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1996.d01-285.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

Complement subcomponent C1q has been recently implicated in the modulation of autocrine binding of TNF‐α to murine macrophages for induction of nitric oxide synthase. In the present study, the putative role of C1q in increasing TNF‐α binding to L929 cells to mediate cytotoxicity was explored. TNF‐sensitive L929 cells (L929‐S) had higher total endogenous cellular and surface C1q levels and bound correspondingly more phycoerythrin‐labelled rTNF‐α (PE‐TNF) than did a TNF‐resistant L929 variant (L929‐R). Pretreatment of L929‐S with soluble C1q increased their sensitivity to TNF‐mediated cytotoxicity coincident with increased binding of PE‐TNF, but similar treatment of L929‐R had no effect. Pretreatment of L929‐S with an inhibitor of C1q secretion, 3,4 dehydro‐D,L‐proline (DHP), resulted in a decrease in their TNF‐mediated cytotoxicity, as well as reduced binding of PE‐TNF. Subsequent exposure of DHP‐treated L929‐S with exogenous soluble C1q restored their TNF‐mediated cytotoxicity and binding of PE‐TNF. These results provide evidence for the modulation of TNF‐α binding to TNF sensitive tumour targets L929 by either endogenously synthesized or exogenously added C1q to promote TNF‐mediated cytot

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1992.d01-284.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

The authors have investigated the presence of serum‐derived immunoglobulin G (IgG) fragments in the human intestine at various ages, these fragments possibly representing another source of antibodies in addition to secretory IgA (SIgA). Fab fragments of the γ isotype were found to be the major molecular form of immunoglobulins in the meconium (median value: 3.7 mg/g of stools), as compared with Fabα (75 μg/g) and IgM (2.6 μg/g). These fragments provided by molecules of the maternal serum displayed a strong antibody activity to the tetanus toxoid and were also found in the stools of 1‐week‐old babies fed with formula milk. The release of serum antibodies into the digestive lumen occurs largely via hepatobiliary secretions, as suggested by the presence of IgG antitoxins in the bile of children operated on extrahepatic biliary atresia. In adults, the Fab antitoxins were also detected in most stool extracts. Affinity of these molecules was found to be similar to that of their serum counterpart with a Ka of 2.1×1010 M1(median value). These mucosal antibody fragments, associated with the normal pathway of serum IgG catabolism, could provide additional immune defences against pathogens, and be of importance to supplement an immature or deficient secre

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1996.d01-288.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

CD3−4−8−interleukin‐2 receptor positive (IL‐2R+) thymocyte precursors from adult mice were cocultured with thymic stromal cells from syngeneic adult mice. The IL‐2R+CD3−4−8−thymocytes were obtained by positive panning of IL‐2R+cells followed by either sorting or negative panning of triple negative cells, and they were cocultured with primary or secondary cultures of heterogeneous thymic stromal cells. Phenotypic maturation of these precursor cells was extremely rapid. Within 2½ days significant numbers of CD4+8+and CD3+4+8−cell populations developed, the latter expressing the αβ T‐cell receptor (αβ‐TCR). Thus heterogeneous stromal cell cultures support the development of IL‐2R+precursors and with these methods it will now be possible to isolate the particular stromal cells involve

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1996.d01-287.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

Monoclonal antibodies (MoAbs) specific for unique epitopes of the catalytic domain of cruzipain (Crz) were used to develop a two‐site sandwich ELISA specific for native Crz. In addition, the authors developed a sandwich ELISA that allowed the detection of the protease C‐terminal domain (CT) using a combination of a MoAb specific for the CT and rabbit anti‐Crz IgGs. Both assays were sensitive with detection limits of 2 ng/ml and 0.7 ng/ml, respectively. The assays were assessed for applicability in detection of antigens in serum and urine from experimentally infected BALB/c mice. The antigens were already detectable in serum by the third week after infection, reached their peak by week four, and decreased during the chronic phase of the infection. Throughout the infection the relative amount of CT detected was several‐fold higher than that of native Crz, and the data demonstrate that the cT exposes highly immunogenic epitopes that are absent in native Crz. Since these observations have a potential application in diagnosis, the authors analysed the degree of cross‐reactivity with antigens fromT.  rangeliT. bruceiLeishmania mexicanaandL. panamensis, and determined that the assays were highly specific. Measurable amounts of the CT were also recorded

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1996.d01-290.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

The role of antigen‐presenting cells (APC) in quantitative antibody synthesis regulation was studied in mice genetically selected for high (HI) or low (LI) antibody response. Irradiated spleen cells and enriched specific B cells from HI and LI mice co‐isogenic atH‐2 slocus, were compared for their capacity to present chicken ovalbumin (OVA) to specific T‐cell hybridomas. Minor differences were observed between HI and LI mice when three distinct hybridomas were stimulated in the presence of OVA and splenic macrophages APC. These differences were totally abolished when APC were pulsed with OVAxAb complexes. Looking at the B‐cell compartment, hybridoma IL‐2 responses were similar when TNP primed B cells were pulsed with OVA. However, when OVA was targeted on TNP‐specific enriched B cells by pulsing with TNP‐OVA, the IL‐2 production by the T‐cell hybridomas was stronger in the presence of HI B cells than in the presence of LI B cells. These results strongly suggest that an efficient Ag handling/processing by specific B cells is a major component of the high Ab responder

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1996.d01-293.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

Four murine IgG1 monoclonal antibodies, each with specificity for a human tumour‐associated antigen, have been tested for theirin vivoimmunogenicity using a rabbit model. Surprisingly, one of these antibodies, MR6, was significantly more immunogenic than the remaining three reagents. This enhanced MR6 immunogenicity was not restricted to the immunoglobulin molecule itself, but also applied to a hapten (fluorescein isothiocyanate, FITC) when conjugated to the monoclonal antibody. In addition, the secondary immune response to an independent antigen, human haemoglobin, was higher when the antigen was administered simultaneously with MR6 than when co‐injected with an isotype‐matched control monoclonal antibody. The presence of the target antigen, gp200‐MR6, on both rabbit and human leucocytes and epithelium, and its known association with human IL‐4 function, raises the possibility that antibody MR6 may not only target immunogens to antigen‐presenting cells, but may also enhance the ability of these cells to present antigen to the immune system. Antibodies to the gp200‐MR6 may therefore find important clinical application asin

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1996.d01-292.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

The authors investigated the time course of monocyte and neutrophil adhesion to fibronectin, vitronectin and albumin precoated culture wells, using mixed leucocyte populations from healthy blood donors. Moreover, the influence of chemotactic agonists on the adhesion properties as well as the quantitative expression of CD29, CD11b/CD18 and CD61 was analysed by flow cytometry. Different chemotactic agonists were used representing a classical chemotactic agonist (fMLP), and agonists with a preferential effect on monocytes (RANTES) and neutrophils (IL‐8), respectively. The authors found a gradual increase in monocyte and neutrophil adhesion to all three surfaces, reaching a plateau at 15 min of incubation. Adhesion to fibronectin was significantly higher at all time points (5, 15 and 60 min, respectively) compared with vitronectin and albumin in both monocytes and neutrophils. Neutrophil adhesion to vitronectin was significantly lower at 60 min compared with 15 min. Monocyte adhesion to albumin was increased by fMLP and RANTES and to vitronectin also by IL‐8. Neutrophil adhesion to albumin and vitronectin was increased by fMLP and IL‐8, but not RANTES. The adhesion to fibronectin was not altered by any of the chemotactic agonists used. The quantitative levels of CD11b/CD18, but not CD29 and CD61, was increased by fMLP, but not RANTES nor IL‐8. The authors conclude that the adhesion of human monocytes and neutrophils to vitronectin and albumin, but not fibronectin, is selectively enhanced by chemotactic agonists and may contribute to the selective accumulation of different leucocyte subsets at the in

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1996.d01-296.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

The authors analysed the effect of protein kinase A (PKA) activation on the protein synthesis and secretion in the T‐helper 2 cell line D10.G4.1 (D10) using an assay that allows the detection of almost all secreted proteins of a cell. IL‐4 and IL‐10 were quantified. Three groups of secretory products could be defined. The T‐cell receptor (TCR)‐induced production of the first group (A) of proteins including IL‐4 was enhanced by low concentrations of PKA activators. At higher concentrations the enhancement was less marked. The synthesis and secretion of a second group (B) of proteins including IL‐10 remained unaffected. The production of a third group (C) of proteins was inhibited in a concentration‐dependent manner. Biochemical analysis revealed a block of phospholipase C γ (PLCγ) activity by PKA activators. When D10 cells were stimulated by a phorbol ester plus calcium ionophore the production of group A proteins was enhanced almost fourfold, whereas production of group B proteins was unaffected by PKA activation. This effect was observed at all concentrations of various PKA activators tested. The secretion of group C proteins was no longer inhibited. The same results were obtained when analysing IL‐4 and IL‐10 m‐RNA by Northern blotting. The data demonstrate a lymphokine specific mode of action on a single cell basis. Furthermore, it suggests that the inhibitory action of PKA in D10 cells is due partly to bl

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1996.d01-295.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

Normal human peritoneal cells collected during elective laparatomy from patients with gallbladder stones without clinically detectable inflammatory changes were characterized phenotypically with immunocytochemical method and flow cytometry, with special attention paid to the presence of memory cells. The responsiveness of normal PCs to mitogen and, specifically, the role of peritoneal macrophages in this process was studied. The peritoneal cells consisted of 45% of monocytes/macrophages (CD68+), as many as CD2+T lymphocytes, 8% CD57+NK and K 2% CD22+B, cells. The CD4/CD8 ratio was 0.4. The peritoneal cells did not express interleukin‐2 (CD25+) and transferrin receptors (CD71+) on their surface. Approximately 49% of the peritoneal cells were class II MHC antigen positive cells. Two per cent of S100+dendritic cells were found. Flow cytometric two‐colour analysis revealed that the majority of peritoneal CD4+(92.4%) and CD8+(73.1%) lymphocytes, while only 50.2% of CD4+and 30.1% CD8+peripheral blood cells expressed simultaneously the CD45RO (UCHL1) molecule, which is characteristic to the memory/effector T‐cell subpopulation. Peritoneal T lymphocytes responded to the mitogens less than peripheral blood lymphocytes of the same individual. Supplementation of cell culture with anti‐macrophage (anti‐CD68) and anti‐HLA‐DR MoAb brought about a dose‐dependent decrease of proliferative peritoneal cell response to ConA. The authors conclude that human peritoneal cell population comprises a high proportion of T lymphocytes and macrophages capable of presenting antigens to peritoneal lymphocytes. High prevalence of memory lymphocytes points to the preparedness of these cells to react with invading antigens most likely of gut b

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1996.d01-297.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY