Biomedical subjects
Publications and source records attributed to S Meuer.
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Human lymphocyte phosphatase-associated phospho-protein (LPAP) is a phosphoprotein of unknown function that noncovalently associates with CD45 in lymphocytes. In CD45-deficient human T cells, LPAP protein is synthesized at normal levels but is more rapidly degraded than in wild-type cells. Expression of CD45 cDNA rescues LPAP protein expression. This strongly suggests that LPAP is protected from degradation through its interaction with CD45. We have mapped the sites of interaction between LPAP and CD45 employing chimeric CD45 molecules and LPAP deletion mutants. Our data demonstrate that the interaction between LPAP and CD45 is mediated via the transmembrane regions of both molecules. In addition, the intracytoplasmic amino acids adjacent to the transmembrane region of LPAP may influence its binding to CD45.
Interleukin 5 (IL-5) is a T-cell lymphokine known to stimulate development, functional activity, and in vitro survival of eosinophils. Tissue and blood eosinophilia occurring during allergic responses of the immune system are potentially mediated by IL-5 secreting T-cells. To test this hypothesis a series of allergen-specific T-cell clones were established from peripheral blood and skin lymphocytes of patients with atopic dermatitis and house dust mite sensitization. In addition, alloreactive T-cell clones were also prepared from peripheral blood lymphocytes of healthy donors. Cloned T-cells were analyzed for IL-5 mRNA expression and IL-5 secretion by means of in vitro gene amplification using the reverse transcriptase polymerase chain reaction and IL-5 specific oligonucleotide hybridization, as well as IL-5-specific ELISA. A majority of allergen-specific long-term cultured T-cell clones (84%) of different donors and of either phenotype (CD8+ or CD4+) disclosed IL-5 transcripts on stimulation with lectins. Almost all clones exhibiting IL-5 transcripts also released immunoreactive IL-5 protein into their culture supernatants. In contrast, only 2% of alloreactive T-cell clones obtained from healthy donors and none of alloreactive T-cell clones of one atopic patient investigated expressed detectable amounts of IL-5 mRNA in response to lectin stimulation, all of whom were CD4+. These results suggest that eosinophilia observed in allergic responses in the peripheral blood and in tissues at the site of induced late-phase cutaneous reaction may be associated with IL-5 release by allergen-specific T-cells.
We present the methodology for 45 degrees retinal photography and detail the development, application and validation of a new system of 45 degrees field grading standards for the assessment of diabetic retinopathy. The systems were developed for the EURODIAB IDDM Complications Study, part of a European Community funded Concerted Action Programme into the epidemiology and prevention of diabetes (EURODIAB). Assessment of diabetic retinopathy was carried out centrally by a trained reader of colour retinal photographs using the newly-developed system. The system proved to be acceptably accurate, repeatable repeatable and relatively simple to apply. It compared well with the recognised 'gold standard' 7-field 30 degrees stereo photography (assessed using a modified Airlie House classification scheme), against which the new system was validated in a series of 48 eyes. Selection was as a stratified random sample based on clinical retinopathy status: 5, no retinopathy; 25, non-proliferative retinopathy; 16, proliferative or photocoagulated; plus 2, eyes with potentially confounding lesions (vein occlusion). Simple presence of retinal lesions was correctly detected by both systems in 43 of the 48 eyes, giving 100% agreement on detection. Both systems correctly identified the two known cases of confounding vein occlusion. In eyes with diabetic retinopathy (n = 41), when severity was expressed in three groups: mild background, moderate/severe background and proliferative/photocoagulated, at least one grader (out of five) using the new system matched the verified results in 38 out of 31 (93%) eyes and three or more graders matched in 31 (76%) eyes.(ABSTRACT TRUNCATED AT 250 WORDS)
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The human foamy virus is a complex retrovirus that codes for several regulatory bel genes in addition to the conventional gag, pol, and env genes. The bel 3 gene is located in the 3' part of the viral genome comparable to that of the superantigen of the mouse mammary tumor virus. Superantigens bound to major histocompatibility complex (MHC) class II molecules have been shown to stimulate T cells in a V beta-specific manner. The recombinant Bel 3 protein purified to near homogeneity was assayed in vitro to determine whether or not it functions as a superantigen that stimulates human T lymphocytes expressing particular V beta T cell receptor (TCR) chains. Therefore, an analysis including all known human V beta elements was performed. The expression of different V beta chains of the TCR was analyzed by reverse transcription of the V beta RNAs and subsequent amplification of the corresponding V beta cDNA elements by polymerase chain reaction in unstimulated, phytohemaggluttinin (PHA)- and Bel 3-stimulated human T lymphocytes. In addition, eight monoclonal antibodies directed against particular V beta family members were used to determine any change in the expression of the remaining known V beta elements upon treatment with PHA and Bel 3. The comparative V beta-specific transcriptional analysis revealed that the in vitro expression of the V beta 18 chain was specifically and strongly expanded in Bel 3-stimulated human T cells, a property characteristic for a superantigen.
We analysed the effect of selective alpha/beta-T cell elimination on allograft survival in a strongly histoincompatible DA-->LEWIS rat model by treatment of recipients with the mouse monoclonal antibody R73 two times before and seven times after transplantation. R73 induced virtually indefinite cardiac allograft survival in 44% of six-week-old LEWIS recipients, whereas donor-type skin allografts were rejected within 11 days. The remaining 56% of animals presented a mean cardiac survival time of 41 +/- 13 days. Graft prolongation was age dependent since in ten-week-old animals the survival time was only of 19 +/- 5 days (untreated controls: 7 +/- 1 days). R73 induced a rapid decrease of R73-positive T cells in the peripheral blood from 70% before treatment to 2%. From the fifth day of treatment a gradual T cell recovery was registered. The T cell marker CD5 decreased from 72% to 17% but recovered already from the second day of treatment. Determination of alpha/beta-TCR, CD3 and CD5 density on T cells during R73 therapy showed that the initial T cell decrease was due to T cell elimination, whereas modulation of alpha/beta-TCR was predominant during the following days. Anti-R73 antibodies appeared regularly during the first week of treatment and blocked R73 activity, indicating their anti-idiotypic nature. The present findings show that short-term R73 therapy is able to induce long-lasting allograft survival. This experimental model can be used to study the basis of peripheral organ specific T cell tolerance.
We tested the ability of lewis (LEW; RT-1(1)) recipients to reject DA (RT-1av1) cardiac allografts following the selective elimination of alpha/beta T cells with the mouse monoclonal antibody R73. One group of adult rats (6 weeks old) received 1000 microg R73 i.p. on days 2 and 1 before transplantation, and 100 microg R73 every third day after transplantation up to day 18. Prolonged cardiac graft survival was noted (30, 30, 32, 51, 62, 108, > 500, > 500, > 500 days). Untreated controls (n = 10) rejected their grafts within 7 +/- 1 days. R73 therapy induced a dramatic decrease in alpha/beta T cells from 69% before treatment to 5% within the first 5 days, followed by an increase to 64% by day 8. The T cell increase was paralleled by the appearance of anti-mouse antibody. A second group of adult rats (10 weeks old) received the same treatment. These "older" recipients rejected their grafts within 20 +/- 5 days. Chronic R73 therapy from birth until the day of transplantation (100 microg R73 i.p. twice a week) resulted in graft survival of 37 +/- 9 days in eight animals. Two rats had a graft survival of more than 200 days. When chronic R73 therapy was continued to day 70 after transplantation, DA hearts were accepted well in all animals for more than 100 days. Alpha/beta T cells were virtually absent throughout the whole time of treatment. Antibodies against R73 were not detected. We concluded that selective elimination of alpha/beta T cells has a strong effect on allograft survival.
The importance of smoking as the most important single cause of death and morbidity is shown. A literature review numbers the most important carcinogens in tobacco and tobacco smoke. Findings of aspects of carcinogenesis and discussions concerning the problem of passive smoking are illustrated as well as their connection with the rise of bronchial carcinoma. It is concluded that in no other carcinoma by evident means--as for instance reduction of cigarette consume--comparable beneficial results could be obtained as in the case of bronchial carcinoma.
We examined 10 different melanoma cell lines for cellular expression and release of ICAM-1 (CD54) and LFA-3 (CD58) and the influence of cytokines, including IFN alpha, IFN gamma and TNF alpha. Cellular ICAM-1 expression and density varies considerably between the melanoma cell lines. While IFN alpha has no effect on cellular ICAM-1 (cICAM-1) expression, IFN gamma and to a lesser extent TNF alpha can effectively up-regulate cICAM-1. Soluble ICAM-1 (sICAM-1) is detected in the supernatants of all lines tested, release of sICAM-1 correlates with cellular expression. LFA-3 does not much differ in its expression level on melanoma lines, and cytokines have little or no effect on its expression. Soluble LFA-3 is released by only 6 out of 10 lines. Its release can effectively be inhibited by IFN gamma in all lines and by TNF alpha in one, while IFN alpha has no effect. These data show that expression and release of LFA-3 and ICAM-1 differ between melanoma cell lines. This may be of importance for the interaction of melanoma cells with immune effector cells in vivo.
Primary biliary cirrhosis is associated with the presence of high-titer anti-mitochondrial autoantibodies as well as T-cell infiltration of the liver, suggesting the involvement of autoimmune mechanisms. We have studied here the sequences of T-cell receptor alpha and beta chains expressed by T-cell clones derived from liver-infiltrating lymphocytes of two patients with primary biliary cirrhosis. Among the eight clones studied from the first patient, four expressed the same member of the V beta 6 subfamily, associated with either V alpha 4 (three clones) or V alpha 21 (one clone) gene segment. Two other clones expressed an identical V beta 12 transcript, and two in-frame alpha chain transcripts, involving V alpha 2 and V alpha 7 gene segments. From the second patient, eight out of the nine clones were found to rearrange V beta 17-J beta 2.1 and V alpha 3 gene segments. The remaining clone expressed distinct T-cell receptor chains, involving V beta 9 and V alpha 11 gene segments. As deduced from the analysis of their junctional regions, the eight T-cell clones expressing V beta 17/V alpha 3 gene segments derived from only three different T cells. Furthermore, conserved amino acid motifs were found to be encoded in both the alpha and the beta-chain junctional regions. Together, these data show a local amplification of unique T lymphocytes in both patients. The use of identical V beta J beta and V alpha gene segments with similar junctional sequences by three different cells, evidenced in one of the two cases, strengthens the view that liver-infiltrating T lymphocytes are selected locally by autoantigens in PBC.
Lectures and presentations at the 1992 Heidelberg Cytometry Symposium reflected a rapidly growing research field with widespread activities that cover daily routine diagnosis as well as investigations at the molecular level and the diagnosis of genetic alterations. Both flow and image cytometry and their impact on quantitative cytology were backed and combined with new approaches (i.e. magnetic cell sorting) that enable the isolation of rare cells with high purity for cell biological analyses and thus pave the way for new research fields (i.e. arteriosclerosis). Their combination with the multicolor painting of gene sequences (fluorescent in situ hybridization) represents a further improvement of chromosome quantification and thus the analysis of the topology of cell nuclei. This year's meeting will be held from 21 to 23 October. Its topics will comprise chromosome painting, apoptosis, automated cytology, bio-imaging and proliferation. As usual, space is given to the presentation of new techniques and concepts. The deadline for abstracts is 30 June.
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Crohn's disease (CD) and ulcerative colitis (UC) show an intestinal activation of T cells and macrophages within the inflamed lesions. The aim of the present prospective study was to determine whether circulating interleukins (IL) represent useful markers of immune activation in vivo and to characterize their respective roles in monitoring disease activity. Serum concentrations of the soluble IL-2 receptor (sIL-2R), IL-6 and IL-1 beta were measured in 10 patients with CD and 10 patients with UC before, at day 10 and 2 years after resection of inflamed bowel segments. The data were correlated with neopterin, C-reactive protein and other standard parameters of disease activity. Preoperatively, mean sIL-2R concentration was 495 +/- 62 U/ml (mean +/- SEM; healthy controls; 210 +/- 25 U/ml; p less than 0.02) in CD and 705 +/- 120 U/ml (p less than 0.00002) in UC. The corresponding IL-6 serum concentrations were 37 +/- 6 U/ml in CD (controls: 11 +/- 0.6 U/ml; p less than 0.0036) and 33 +/- 6 U/ml (p less than 0.04) in UC. Two years postoperatively, sIL-2R was still elevated in 6 out of 9 patients in both disease groups. These patients did not differ from the remaining group with respect to disease activity. Serum IL-6, elevated in 7 patients with CD and in 6 patients with UC at day 10 postoperatively, had returned to normal in all patients by this time.(ABSTRACT TRUNCATED AT 250 WORDS)
Secondary immunodeficiency is frequently observed in Hodgkin's disease (HD) and is due in part to impaired T-cell function. Using monoclonal antibodies that bind to triggering molecules of human T lymphocytes (CD3/Ti antigen receptor; CD2 E-rosette receptor) and exert functional effects on T-cell activation, we have investigated in vitro immune responses of circulating lymphocytes from patients with HD in progression (n = 9) and in remission (n = 14). In patients with progressive HD, a severe dysfunction of the alternative CD2-mediated T-cell activation pathway was detected (49.3 +/- 14.2 v 9.4 +/- 5.1 cpm x 10(-3), in controls, P less than .01; n = 9) that parallels the reduced capacity of T lymphocytes to form rosettes with sheep red blood cells. Diminished alternative pathway activation in HD is not only due to a defect at the cellular level but also due to soluble mediators in the patients' plasma. Plasma from patients in progression markedly reduces CD2 mediated activation (P less than .01). These activities interfere, at least in part, with CD2/CD58 interactions and, therefore, reduce T-lymphocyte triggering through this amplifier mechanism.
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In vitro protein kinase assays of CD45 immunoprecipitates prepared from digitonin lysates of resting human T lymphocytes resulted in exclusive tyrosine phosphorylation of a 32-kDa protein (pp32). Reprecipitation of the in vitro phosphorylated proteins and Western blot analysis of whole CD45 immunoprecipitates employing antisera specifically directed at different protein tyrosine kinases demonstrated that the p56lck protein tyrosine kinase was responsible for in vitro phosphorylation of pp32. Since in vitro kinase assays of p56lck immunoprecipitates also resulted in phosphorylation of pp32, the present data strongly suggest that a functional complex is formed between CD45, p56lck and pp32. Such a notion is supported by the findings that phosphorylation of pp32 by p56lck correlated with expression of the CD45 molecules and that in vitro phosphorylated pp32 was completely dephosphorylated by purified CD45.