摘要:

Given that the associative recognition of antigen (two signal) model permits a certain level of ‘autoreactivity’, Faro&Carneiro argue that this unavoidable ‘autoreactivity’ is required as part of the regulation of thegeneral physiology of the animal. This paper gives the author’s reply pointing out two facets of the functioning of the immune system. (1) Under an associative recognition of antigen model, the scenarios of B‐cell activation postulated by them areruled out. (2) There is no way to use a destructive ridding effector function to regulate the self/non‐self discrimination because autoimmune reactivity would accompany any postulated regulat

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1996.d01-17.x-i2

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1996.d01-18.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

ISSN:0300-9475    

DOI:10.1046/j.1365-3113.2002.271br.x-i1

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

Treatment of Swiss albino mice with histamine enhanced the clearance of natural killer (NK)‐cell sensitive YAC‐1 lymphoma and B16/F10 melanoma cells from lung tissuein vivo, but did not affect the elimination of NK‐cell‐insensitive P815mastocytoma cells. The effect of histamine was apparently mediated by H2‐type histamine receptors (H2R) since it was blocked by ranitidine, an H2R antagonist. Histamine did not affect clearance of tumour cells in animalsdepleted of NK cellsin vivoby treatment with antibodies to asialo‐GM1 or NK1.1. The effect of histamine was time‐dependent: pretreatment with histamine for 3 h significantly augmented the clearance of YAC‐1 cells, whereas, pretreatmentwith histamine for 5 min was ineffective. Histamine potentiated the anti‐tumour properties of NK‐cell activators such as interleukin‐2 (IL‐2) or interferon‐α (IFN‐α)in vivo. None of these lymphokines significantly affected theclearance of YAC‐1 cells unless animals were concomitantly treated with histamine. Treatment with ranitidine alone reduced thein vivoclearance of YAC‐1 cells from lungs but did not affect the clearance of NK‐cell‐insensitive P815 cells. Effects of ranitidine on NK‐cell functionin vivowere not shared by a chemical control to ranitidine, AH20239AA, thus indicating that the inhibition of NK‐cells results from H2R antagonism rather than non‐specific toxicity. It is concludedthat histaminergic mechanisms may be invol

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1996.d01-14.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

Antibody‐dependent cellular cytotoxic (ADCC) activity of cells in rat metrial glands at days 13 and 20 of pregnancy has been examined. A51chromium‐release cytotoxicity assay was carried out using Yac‐1 cells and P815 cells as targets in the presence of the corresponding, heat inactivated rat antibody or non‐immune rat serum. No killing was observed when effector metrial gland cells and target cells were cultured in the presence of non‐immune rat serum. In the presence of rat antibody toYac‐1 cells, or rat antibody to P815 cells, cells from the metrial glands of rats killed at day 13 of pregnancy demonstrated ADCC activity, but cells from the metrial glands of rats killed at day 20 of pregnancy showed no ADCC activity. Spleen andperitoneal exudate cells displayed ADCC activity. Immunohistological and immunocytological studies showed OX‐6, OX‐34, OX‐35 and OX‐42 positive cells were present at days 13 and 20 of pregnancy, in sections of metrial glands and in the cell suspensionsprepared for the cytotoxicity assays. It is suggested that macrophages are the cells most likely to be responsible for the ADCC activity in th

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1996.d01-6.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

Follicular dendritic cells (FDC) are unique non‐lymphoid cells found only in lymph follicles. They play a part in the survival, proliferation and differentiation of B cells. To analyse the influence of FDC on B‐lymphocyte proliferation, we isolatedthem from human tonsils on albumin gradients and treated them with mitomycin C to prevent the multiplication of lymphoid cells harboured in their cytoplasmic evaginations. FDC cultured for 12–16 h remained attached to the substrate;non‐adherent cells were carefully eliminated by washing. Purified B cells cultured alone or with contaminant‐cleared FDC were maintained for 2 days in the presence or absence of various stimulants, after which tritiated thymidine uptake by these cells was measured. In the absence of activators, FDC did not induce B‐cell multiplication. B cells cultured in the presence of FDC exhibited increased3H‐TdR uptake when activated with anti‐CD40 MoAb, anti‐immunoglobulin MoAb or transferrin, but notwhen stimulated withStaphylococcus aureusstrain Cowan I (SAC) at a given concentration. In the latter case, B‐cell proliferation clearly decreased. In control cocultures where mitomycin‐C‐treated non‐adherent cells were used instead of FDC inthe presence of the different stimulants, no increase in B‐cell proliferation was observed. The results suggest that, inside the germinal centres, FDC modulation of B‐cell proliferation depends on the activation state of the B cells

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1996.d01-7.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

Afferent lymph dendritic cells were analysed for the presence of Fcγ receptors by Western blotting and for modulation of surface markers following Fcγ receptor engagementin vitroandin vivo. The results showed thatunstimulated dendritic cells expressed FcγRII constitutively. When dendritic cells were incubatedin vitrowith antigen/antibody complexes in antibody excess, a marked reduction in surface staining was observed for MHC class II, CD1, CD44,and VLA‐4 after 8 h in culture. These changes did not occur with antigen or antibody alone. DC expression of LFA‐1 and LFA‐3 were slightly reduced after 8 h in culture with Ova alone, but this was enhanced slightly when the cells werecultured with immune complexes. Even more marked reductions in surface staining for MHC class II, CD1, CD44 and VLA‐4 were observed on dendritic cells 4–8 h following secondary antigen challengein vivo. LFA‐1 and LFA‐3 expressionwas reduced only slightly. The level of expression of MHC class II, CD1, LFA‐1 and LFA‐3 was substantially increased over resting values 24 h after FcγR occupancy. The intensity of staining at this time was also significantly elevated for CD44, LFA‐1, LFA‐3 and VLA‐4. These results show that engagement of Fcγ receptors cause a substantial modulation of the dendritic cell surface phenotype after immune complex uptake. The phenomenon may function to maximize subsequent presentatio

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1996.d01-11.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

Reactive arthritis is usually self‐limiting polyarthritis which develops in HLA‐B27 positive individuals after certain gastrointestinal or urogenital infections. The pathogenesis of reactive arthritis is unknown but T cells seem to have a crucial role. Most of the antigen‐specific T cells isolated from the synovial fluid have been MHC class II restricted. The role of antigen presentation in the pathogenesis of reactive arthritis has been studied relatively little. In this work the authors studied theeffect of arthritis‐triggering bacterium (Yersinia enterocoliticaO:3) on the expression of MHC class II molecules on human monocytes and found that the expression of different MHC class II molecules was regulated independently from each other in half of the individuals after certain incubation periods. In these cases the expression of HLA‐DP was parallel to the expression of HLA‐DQ, while HLA‐DR expression went to the opposite direction or did not change at all. No difference between HLA‐B27negative and HLA‐B27 positive healthy individuals was seen. The authors conclude that independent regulation of the expression of different MHC class II antigens on antigen‐presenting cells is a more common phenomenon t

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1996.d01-3.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

Expression of CD40 on mouse cells was investigated comparing the binding to cells of a monoclonal antibody against CD40, to that of a soluble fusion protein consisting of the extracellular domains of the mouse CD40‐ligand. The analysis of a series ofestablished cell lines failed to demonstrate expression of CD40 on pro‐ or pre‐B cells, and indicated that CD40 expression was restricted to cells that had undergone productive heavy‐ and light‐chain gene rearrangements, and expressed surface Ig. In cells from normal mice, CD40 first becomes detectable, although at low levels, on a subset of small pre‐B‐II cells in bone marrow, the levels of CD40 expression increasing thereafter during B‐cell maturation. Thus, immature B cells (IgM+IgDloB220lo) express intermediate levels of CD40, and mature B cells (IgM+IgDhiB220hi) express high levels of CD40. Anatomical location also seems to correlate with the levels of CD40expression, as B cells expressing the highest levels of CD40 were found in lymph nodes and

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1996.d01-13.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY

摘要:

Oral tolerance was induced in 4‐week‐old (young) and 12‐week‐old (adult) rats by feeding ovalbumin (OvA)‐containing pellets during 4 weeks. Seven weeks after removal of the OvA‐pellets the rats were immunized with a mixture of OvA and human serumalbumin (HSA) in Freund’s complete adjuvant (FCA), and the following immune response was monitored. Both the young and adult groups of OvA‐fed rats had significantly suppressed OvA‐specific delayed‐type hypersensitivity (DTH) responses and T‐cellproliferation, reflecting a long‐lasting T‐cell tolerance to OvA both in vivo and in vitro. Furthermore, spleen cells from rats tolerized as adults were able to suppress the proliferation of primed T‐cells from normal immunized rats, demonstrating thepresence of antigen‐specific suppressive cells. Accordingly, the adult rats showed bystander suppression of the response to HSA with respect to DTH‐reaction, specific proliferation, and reduced enlargement of the draining lymph nodes after immunization.There was no evidence of active suppression in vitro or bystander tolerance in the orally tolerized young group, indicating that anergy rather than active suppression was prevalent in these rats. Furthermore, in the young group there was no suppression of the antibody response since the IgG and IgE anti‐OvA antibody levels were indistinguishable from those of the controls. Contrary to the young rats, the adult fed group showed transiently elevated levels of IgG anti‐OvA antibodies at 1 weekpost‐immunization, followed by a subsequent significantly suppressed IgG antibody response. In conclusion, the results demonstrate that the induction of anergy or active suppression after antigen feeding can be determined by the age at which the antigenis in

ISSN:0300-9475    

DOI:10.1046/j.1365-3083.1996.d01-15.x

出版商:Blackwell Science Ltd    

年代:1996

数据来源: WILEY