摘要:

AbstractPhorbol myristate acetate (PMA) can induce a rapid and significant decrease in the expression of IgE receptors on RBL‐2H3cells. Fluorescence microscopy confirmed that the down‐regulation is due to internalization of receptors. The endocytotic response to PMA shares several characteristics with endocytosis induced by immunochemical aggregation of surface‐bound monomeric IgE: the rates of internalization both have a t1/2of about 5 min, a maximum of 35% of the surface‐bound IgE can be endocytosed by the action of PMA (50% by receptor aggregation), endocytosis is sustained for at least up to 60 min, neither stimulus requires extracellular Ca2+and endocytosis induced by either stimulus is an active process,i.e., is dependent on temperature and cellular energy. Biochemical studies revealed some differences between the endocytotic responses to the two stimuli. After prolonged treatment of cells with dexamethasone, only endocytosis induced by PMA is inhibited. Cells depleted of protein kinase C by prolonged exposure to PMA can sustain a significant endocytotic response to aggregation of IgE receptors, but become completely desensitized to PMA. These data suggest that different biochemical pathways mediate the signals from the two stimuli and that protein kinase C is directly involved in endocytosis induced by PMA but does not have a major role in endocytosis induced by receptor aggr

ISSN:0014-2980    

DOI:10.1002/eji.1830191002

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractIn this investigation we have examined some of the cellular and molecular changes in efferent lymph that drains from an antigen‐stimulated peripheral lymph node. Resting efferent lymph is characterized by a higher percentage of CD4+cells and consequently, a higher CD4/CD8 ratio than peripheral blood. Following antigen stimulation of a cannulated peripheral lymph node in antigen‐primed sheep, the percentage of CD4+cells in efferent lymph increases above the resting level during days 1, 2 and 3 post antigen stimulation. This is followed on days, 3, 4, and 5 after antigen stimulation by an increase in the percentage of CD8+cells above the resting level which occurs as the percentage of CD4+cells returns to the resting level. These changes cause the CD4/CD8 ratio to first increase above the resting value during the CD4 phase and then decrease below the resting value during the CD8 phase. During the CD4 phase a lymphokine activity is present in cell‐free lymph fluid. Lymph fluid collected at this time supports the proliferation of activated T cells. Supernatants generated from efferent cells collected at a similar time and culturedin vivofor 24 h without any further stimulation are capable of releasing this material. During the CD8 phase cells expressing functional interleukin(IL) 2 receptors appear in lymph fluid. The data suggests a sequential exit of T cell subsets from an antigen‐stimulated lymph node and that the appearance of IL 2‐like activity and IL 2‐responsive cells in efferent lymph fluid are temporally dist

ISSN:0014-2980    

DOI:10.1002/eji.1830191003

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractIn an outcross between a diabetic BB/H rat and a healthy Long Evans Hooded rat, the segregation of the RT6 gene was studied in the 207 F2animals to look for linkage with diabetes or lymphopenia. The recessive gene, albino (c), was used as a marker for the RT6 gene because of the close proximity of these two genes on chromosome 1. Though most of the albino F2rats should have been homozygous for the BB RT6 gene, we found no increase in the incidence of diabetes or lymphopenia among them when compared to their hooded littermates. Therefore, the RT6 gene was not linked to diabetes or lymphopenia in the BB rat. Moreover, the non‐lymphopenic albino rats displayed normal RT6 expression when compared to the normal hooded rats showing that the RT6 gene from the BB/H grandfather was not defective. Any alteration in lymphocyte composition which could be specifically related to diabetes was studied by measuring all F2rats for the major lymphocyte subsets including the RT6+subset. We found that the typical pattern of lymphopenia described in diabetic BB rats was displayed by both diabetic and non‐diabetic lymphopenic rats in the F2generation. Thus, all these lymphocyte abnormalities including the depletion in RT6+T lymphocytes appeared as a consequence of lymphopenia alone and could not be specifically related to diabe

ISSN:0014-2980    

DOI:10.1002/eji.1830191004

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractIt has long been recognized that T cells in the cerebrospinal fluid (CSF) and other inflammatory compartments cannot be stimulated by mitogen and the reason for this has remained unknown. This question was investigated using mononuclear cells (MNC) isolated from the CSF of subjects with multiple sclerosis and other inflammatory brain diseases which predominantly express the CD4 and CDw29 but not CD45RA determinants. CSF and blood cells were stimulated by either the CD3/T cell receptor complex, the CD2 activation pathway, calcium ionophore, or an activator of protein kinase C, phorbol myristate acetate (PMA). CSF MNC proliferated less than blood MNC following stimulation by phytohemagglutinin in subjects with inflammation in the CSF, but not in subjects with non‐inflammatory CNS diseases. Moreover, CSF MNC were not induced to proliferate through stimulation of the CD2 pathway by anti‐T112+ anti‐T113monoclonal antibodies (mAb). This was not due to defects in either interleukin 2 receptors, interleukin 2 secretion, or to T cell pre‐activationin vivo.Instead, the refractory activation state of inflammatory CSF T cells was corrected by PMA. That CSF contains predominantly CD4+CDw29+CD45RA‐cells suggests that PMA may be co‐stimulatory with anti‐CD2 mAb to activate this population of T cells. This was confirmed in experiments with sorted T cells from normal subjects. These data suggest that the inability of mitogens or anti‐CD2 mAb to stimulate inflammatory CSF T cells, which can be corrected by an inducer of protein kinase C, is related to the relative absence of CD4+CD45RA+cells in the CSF. Alterations of protein kinase C and protein phosphorylation may exist in inflammatory T cell populations that regulate the

ISSN:0014-2980    

DOI:10.1002/eji.1830191005

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractEight novel human T cell epitopes were identified within the two major merozoite surface antigens (MSA1 and MSA2) ofPlasmodium falciparumusing synthetic peptides. All except one of the peptides conformed structurally to an amphipathic α helix and three out of the four MSA1 peptides also contained sequences containing the Rothbard motif. Peptide MSA2/2, which fitted none of these criteria, was recognized by our donors to a similar degree as the other peptides. This peptide also contains a B cell epitope. Proliferative responses were obtained in both immune and nonimmune donors, however, the number of responses in the immune donor group was significantly higher. There was no correlation between the level of proliferation and antibody titers to these antigens. No peptides were preferentially recognized in association with specific HLA class II antigens

ISSN:0014-2980    

DOI:10.1002/eji.1830191006

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractToxic shock syndrome toxin‐1 (TSST‐1)‐binding assay using125I‐labeled TSST‐1 showed the presence of specific TSST‐1 binding in a B cell fraction of human peripheral blood mononuclear cells and L cells transfected with DR2 genes or DR4 genes but not in a T cell fraction and control L cells. Fixation with paraformaldehyde, an inhibitor of antigen processing, did not remove TSST‐1‐binding activity of the transfectants. Binding of125I‐labeled TSST‐1 to the transfectants was reduced by an anti‐DR monoclonal antibody. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis revealed the presence of a single band with TSST‐1‐binding activity and the same migration pattern as DR heterodimers. TSST‐1‐induced T cell responses, proliferation and interleukin 2 (IL2) production were observed in the presence of the transfectants but not in the presence of control L cells, while concanavalin A‐induced IL2 production was observed in the presence of either the transfectants or control L cells. Presence of an anti‐DR monoclonal antibody inhibited the TSST‐1‐induced responses. Paraformaldehyde‐fixed Daudi cells were effective in supporting TSST‐1‐induced IL2 production by T cells. These results indicate that HLA class II molecules directly bind intact TSST‐1 and perform an essential role as the TSST‐1‐binding structures o

ISSN:0014-2980    

DOI:10.1002/eji.1830191007

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractEarly in ontogeny B cells preferentially use VHgene families which are most adjacent to the genes coding for the constant part of the immunoglobulin molecule. In conventional adult mice, however, a random usage of VHgene families has been found. We investigated the role of exogenous antigenic stimulation on this normalization of VHgene usage by B cells. Therefore, we made use of adult germ‐free BALB/c mice fed a chemically defined ultrafiltered antigen‐free diet (GF‐CD) and neonatal conventional BALB/c mice. Both the adult GF‐CD and the newborn conventional mice represent situations with minimal exogenous antigenic stimulation. The results obtained with RNA dot blot hybridization with probes specific for the different VHgene families showed in hybridomas from adult GF‐CD BALB/c mice a preferential usage of the CH‐proximal VHgene family PC7183. In hybridomas from 5‐day‐old conventional BALB/c mice a less frequent usage of the J558 VHgene family was found and an increased usage of the PC7183 VHgene family than what would be expected from random usage. Evidence is presented that the RNA giving a positive signal with the PC7183 probe represents functional messages for

ISSN:0014-2980    

DOI:10.1002/eji.1830191008

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractHybridomas were derived from lipopolysaccharide‐reactive splenic B cells of adult germ‐free BALB/c mice fed a chemically defined ultrafiltered “antigen‐free” diet (GF‐CD) and from splenic B cells of 5‐day‐old conventional (CV‐NEO) BALB/c mice. The monoclonal antibodies (mAb) from both collections of hybridomas were tested for reactivity against a large panel of antigens of exogenous and endogenous origin. As a source of natural exogenous antigens 36 different bacteria and 9 different viruses were used, while as endogenous antigens frozen tissue sections of stomach, liver and kidney, the Hep‐2 cell line and the anti‐idiotopic mAb Ac38 and Ac146 were used. In both collections of mAb approximately 70% reacted with one or more bacterial antigens, while no reactivity could be detected against the viral antigens. Of the GF‐CD and CV‐NEO hybridomas, 16% and 19%, respectively, reacted with one or more frozen tissue sections. Overall 56% and 68% of the GF‐CD and CV‐NEO hybridomas, respectively, were producing multireactive antibodies reactive to several exogenous and/or endogenous antigens.Among the GF‐CD hybridomas a correlation was found between multireactivity and the usage of the VHgene family PC7183. In CV‐NEO hybridomas, however, the preferential utilization of the VHgene family PC7183 was found among both mono‐and multireactive hybridomas. The results suggest (a) that the actual B cell repertoire of neonatal mice consists of a large proportion of multireactive B cells which are reactive with autoantigens and bacterial antigens, but not viral antigens and (b) that in antigen‐deprived mice the neonatal repertoire is largely pr

ISSN:0014-2980    

DOI:10.1002/eji.1830191009

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractThe humoral immune response to a 72‐kDa heat shock‐like protein ofPlasmodium falciparumhas been analyzed using mouse monoclonal antibodies (mAb) and human immune sera. Three regions of the molecule containing B cell epitopes were identified by screening a sublibrary encoding the COOH‐terminal half of the antigen with the mAb. One B cell epitope mapped to a region poorly conserved between the parasite 72‐kDa polypeptide and mammalian heat‐shock proteins (Hsp 70). Another mAb, G10C9, reacted with an amino acid region that has a high degree of homology with mouse (87.5%) and human (81.2%) Hsp 70. Both mouse and human cells were recognized by this mAb when analyzed by indirect immunofluorescence and by two‐dimensional immunoblots. Sera from humans infected with malaria also recognized the human Hsp 70. Thus, our results indicate that autoantibodies directed against host Hsp 70 can be induced by the homologous paras

ISSN:0014-2980    

DOI:10.1002/eji.1830191010

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY

摘要:

AbstractDendritic cells from human epidermis,i.e., Langerhans cells (LC), are more potent antigen‐presenting cells (APC) than APC from peripheral blood in proliferativein vitroresponses of helper T lymphocytes to various soluble antigens. Analysis of antigen recognition by CD4+T lymphocyte clones indicated that this increased potency of LC as APC results from a preferential requirement for LC of part of the T cell population. These T cells show a long‐lasting restoration of antigen responsiveness to peripheral blood APC after antigen‐specific restimulationin vitro, indicating that restrictive antigen recognition concerns T cells that are not fully differentiated. A similar restrictive antigen recognition was observed by treatment of the T cells or the APC with neuraminidase. This restoration of responsiveness is associated with the occurrence of nonspecific cell clustering between T cells and APC. These results suggest that the selective requirement for APC is regulated by the function of adhesion molecules that are functionally blocked by sialic acid groups on immature peripheral T cells but that are readily available on peripheral T cells at a later stage of differenti

ISSN:0014-2980    

DOI:10.1002/eji.1830191011

出版商:WILEY‐VCH Verlag GmbH    

年代:1989

数据来源: WILEY