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T Kamradt

Publications and source records attributed to T Kamradt.

At least 37 records · Page 2Linked to original sources
PubMed1998

Detection of Borrelia burgdorferi by polymerase chain reaction in synovial membrane, but not in synovial fluid from patients with persisting Lyme arthritis after antibiotic therapy.

OBJECTIVES: To identify possible sites of bacterial persistence in patients with treatment resistant Lyme arthritis. It was determined whether Borrelia burgdorferi DNA may be detectable by polymerase chain reaction (PCR) in synovial membrane (SM) when PCR results from synovial fluid (SF) had become negative after antibiotic therapy. METHODS: Paired SF and SM specimens and urine samples from four patients with ongoing or recurring Lyme arthritis despite previous antibiotic therapy were investigated. A PCR for the detection of B burgdorferi DNA was carried out using primer sets specific for the ospA gene and a p66 gene of B burgdorferi. RESULTS: In all four cases, PCR with either primer set was negative in SF and urine, but was positive with at least one primer pair in the SM specimens. In all patients arthritis completely resolved after additional antibiotic treatment. CONCLUSIONS: These data suggest that in patients with treatment resistant Lyme arthritis negative PCR results in SF after antibiotic therapy do not rule out the intraarticular persistence of B burgdorferi DNA. Therefore, in these patients both SF and SM should be analysed for borrelial DNA by PCR as positive results in SM are strongly suggestive of ongoing infection.

Adult↗
PubMed1997

T cell cytokine pattern in the joints of patients with Lyme arthritis and its regulation by cytokines and anticytokines.

OBJECTIVE: To investigate whether type 1 helper (Th1) or Th2 cytokines are found in the joints of patients with Lyme arthritis, and whether the cytokine pattern can be modulated by cytokines or anticytokines. METHODS: The cytokine pattern in the joints of 10 patients with Lyme arthritis was investigated. Expression of interferon-gamma (IFN gamma), tumor necrosis factor alpha (TNF alpha), interleukin-4 (IL-4), and IL-10 was measured by enzyme-linked immunosorbent assay (ELISA), after stimulation of synovial fluid mononuclear cells (SFMC) with Borrelia burgdorferi (Bb) in the supernatant. Expression of cytokine messenger RNA and protein in synovial membrane (SM) and nonstimulated SFMC was studied using semiquantitative reverse transcriptase-polymerase chain reaction and immunohistologic techniques. The effects of recombinant cytokines or neutralizing anticytokine antibodies on cytokine production in Bb-stimulated SFMC were investigated by ELISA. RESULTS: SFMC produced high amounts of IFN gamma and TNF alpha, but little or no IL-4, upon stimulation with Bb antigen, indicating a Th1-type cytokine pattern. In SM, IFN gamma was detectable in all patients, while the other cytokines were less frequently found. Serial sections of SM revealed that all cytokines were located in the same area. The Th1 response, especially the production of TNF alpha, could be down-regulated in vitro by both endogenous and exogenous IL-10, but not by IL-4 or anti-IL-12. CONCLUSION: A Th1-type cytokine pattern was found in the joints of patients with Lyme arthritis. This Th1 response could be down-regulated by IL-10, suggesting insufficient IL-10 production in vivo.

Adolescent↗
PubMed1997

Lipopeptides of Borrelia burgdorferi outer surface proteins induce Th1 phenotype development in alphabeta T-cell receptor transgenic mice.

Induction of the appropriate T helper cell (Th) subset is crucial for the resolution of infectious diseases and the prevention of immunopathology. Some pathogens preferentially induce Th1 or Th2 responses. How microorganisms influence Th phenotype development is unknown. We asked if Borrelia burgdorferi, the spirochete which causes Lyme arthritis, can promote a cytokine milieu in which T cells which are not specific for B. burgdorferi are induced to produce proinflammatory cytokines. Using alphabeta T-cell receptor transgenic mice as a source of T cells with a defined specificity other than for B. burgdorferi, we found that B. burgdorferi induced Th1 phenotype development in ovalbumin-specific transgenic T cells. Small synthetic lipopeptides corresponding to the N-terminal sequences of B. burgdorferi outer surface lipoproteins had similar effects. B. burgdorferi and its lipopeptides induced host cells to produce interleukin-12. When the peptides were used in delipidated form, they did not induce Th1 development. These findings may be of pathogenic importance, since it is currently assumed that a Th2-mediated antibody response is protective against B. burgdorferi. Bacteria associated with reactive arthritis, namely, Yersinia enterocolitica, Shigella flexneri, and Salmonella enteritidis, had different effects. The molecular definition of pathogen-host interactions determining cytokine production should facilitate rational therapeutic interventions directing the host response towards the desired cytokine response. Here, we describe small synthetic molecules capable of inducing Th1 phenotype development.

Animals↗
PubMed1997

An optimized PCR leads to rapid and highly sensitive detection of Borrelia burgdorferi in patients with Lyme borreliosis.

The present study aimed at developing an optimized PCR protocol fro the sensitive and specific detection of all three Borrelia burgdorferi genospecies pathogenic to humans in Lyme borreliosis patients. A rapid DNA extraction method using alkaline lysis was introduced and was found to be superior to other DNA extraction methods. Nested PCR was performed with primer sets targeting the plasmid-located ospA gene and a chromosomal gene segment encoding a 66-kDa protein (p66). In spiked synovial fluid (SF) fewer than three borreliae/sample were detected. The specificities of the amplicons were confirmed by Southern blot analysis with PCR-derived probes. Urine, cerebrospinal fluid (CSF), and SF specimens from 57 patients with Lyme borreliosis and from 58 controls were examined. In clinical samples the diagnostic sensitivity of PCR was 85% with SF samples, 79% with urine samples, and 91% with paired SF-urine samples from patients with Lyme arthritis and was 79% with CSF samples, 45% with urine samples, and 87% with paired CSF-urine specimens from neuroborreliosis patients. One patient each with neuroborreliosis and with Lyme arthritis had PCR-positive urine samples only. In 17% of all cases both primer sets yielded positive results, while the other patients were positive with only one primer set. Among these, more positive results were obtained with the p66 gene primer than with the ospA primer. The specificity exceeded 99%. We conclude that DNA from B. burgdorferi sensu lato species can sensitively and specifically be detected with the optimized PCR method described. At least two different primer sets should be used, and whenever possible, urine and CSF or SF should be analyzed in parallel to achieve maximum sensitivity of the test. This protocol, therefore, considerably enhances the diagnostic power of PCR in patients with B. burgdorferi infection.

Adolescent↗
PubMed1996

Peripheral tolerance in T cell receptor-transgenic mice: evidence for T cell anergy.

T cell tolerance can be induced in adult mice by injection of soluble antigenic peptide. The underlying mechanism has been difficult to establish in normal mice due to the low precursor frequency of T cells specific for any given antigen. Therefore, we examined peripheral tolerance in mice transgenic for a T cell receptor specific for a cytochrome c peptide bound to I-Ek. Antigen-specific hyporesponsiveness could be induced in the transgenic mice. We followed the transgene-bearing T cells with a clonotypic monoclonal antibody and found similar numbers of clonotypic T cells in tolerized and control mice. To prevent de novo differentiation of T cells we analyzed thymectomized mice in which antigen-specific hyporesponsiveness was induced. Our analysis of thymectomized transgenic mice showed that antigen-specific T cell hyporesponsiveness following injection of peptide intravenously is not caused by gross elimination of T cells. These data provide evidence for the role of anergy in peripheral tolerance.

Amino Acid Sequence↗
PubMed1996

Potential infectious agents in the induction of arthritides.

In the multifactorial etiology of rheumatic diseases, infectious agents are regarded as the major environmental factors that may cause inflammatory arthritides in genetically susceptible hosts. Two not mutually exclusive pathogenetic pathways are hypothesized to explain the initiation and perpetuation of chronic arthritides by infectious agents: persistent infection and induction of immunopathology. In this review we focus on the role of infections in the etiopathogenesis of rheumatoid arthritis. Retroviruses and enteropathogenic bacteria continue to be the most intensively discussed candidates as possible etiologic factors of rheumatoid arthritis. Although there is ample indirect evidence for the involvement of infections in the pathogenesis of autoimmune disease, direct proof is still missing. There may be no single infectious trigger for rheumatoid arthritis, but multiple infectious agents that share antigenic motifs. The "reverse immunology" approach addresses this issue and is discussed in our outlook on future research directions.

Arthritis↗
PubMed1996

Dominant recognition of a Borrelia burgdorferi outer surface protein A peptide by T helper cells in patients with treatment-resistant Lyme arthritis.

In an earlier study, we found that T-cell lines (TCL) from five patients with treatment-resistant Lyme arthritis preferentially recognized Borrelia burgdorferi outer surface protein A (OspA), but TCL from four patients with treatment-responsive arthritis only rarely recognized this protein. Dominant T-cell recognition of an arthritogenic OspA epitope is one way in which the immune response against OspA might be involved in the pathogenesis of treatment-resistant Lyme arthritis. In an effort to test this hypothesis, we mapped the epitopes of 31 OspA-specific TCL and five T-cell clones derived from the synovial fluid or peripheral blood samples of three patients with treatment-resistant Lyme arthritis. Although each patient's TCL recognized a broad array of OspA peptides with different individual patterns, two regions of OspA were dominantly recognized. Each patient's TCL dominantly recognized a C-terminal epitope of OspA, ranging from amino acids (aa) 214 to 233 in one patient to 244 to 263 in another, and the TCL of all three patients dominantly recognized an epitope between aa 84 and 113. These dominant regions were confirmed by clonal analysis in one patient. Thus, the region of OspA between aa 84 and 113 was the dominant T-cell epitope shared by these three patients with treatment-resistant Lyme arthritis. If the T-cell response to OspA is involved in the pathogenesis of treatment-resistant Lyme arthritis, and epitope contained within aa 84 to 113 is a potentially arthritogenic epitope.

Adult↗
PubMed1995

Immunology of reactive arthritides.

Reactive arthritis (ReA) and Lyme arthritis together comprise a pair of chronic inflammatory diseases of the joints. Although differing in detail, these relatively rare diseases are related in their immunopathology to the much commoner rheumatoid arthritis (RA), for which they serve as both model and control. The trigger for rheumatoid arthritis is unknown, but for these rarer diseases triggering occurs by certain well-defined bacterial infections. Arthritis is an uncommon outcome of these infections, for reasons unknown, and the development of chronic, as distinct from brief, arthritis is even rarer; again, the reasons are unknown. Not only does knowing the trigger greatly assist us in understanding these diseases, so also does knowing the contrasting pattern of Th1 versus Th2 cytokines observed in RA and ReA. ReA and Lyme arthritis are here considered in the wider setting of infections where chronic morbidity arises first from hypersensitivity, and perhaps finally from autoimmunity, such as occurs in some of the major tropical diseases. The immunology of ReA and Lyme disease is surveyed in detail, concentrating on T cells and including an update on the Lyme vaccine(s). Additional sections deal with the enigma of HLA B27, with epidemiological findings relevant to the chronicity of ReA and to the need for enlarged prospective studies of ReA in the setting of a developing country.

Arthritis, Reactive↗
PubMed1994

The T helper cell response in Lyme arthritis: differential recognition of Borrelia burgdorferi outer surface protein A in patients with treatment-resistant or treatment-responsive Lyme arthritis.

The host response to Borrelia burgdorferi is likely to play a role in the pathogenesis of Lyme arthritis. Whereas most patients with Lyme arthritis can be cured with antibiotic therapy, approximately 10% of the patients have persistent arthritis for months or even several years after antibiotic treatment. In this study, we tested the hypothesis that the T cell response to one or more antigens of B. burgdorferi is different in patients with treatment-responsive or treatment-resistant Lyme arthritis. For this purpose, 313 B. burgdorferi-specific T cell lines were derived from the synovial fluid or peripheral blood of four patients with treatment-responsive Lyme arthritis and five patients with treatment-resistant arthritis. 87 T cell lines from treatment-responsive Lyme arthritis and 112 lines from the treatment-resistant group were examined for the recognition of five recombinant. B. burgdorferi proteins: outer surface proteins A (OspA), B, C, p39, and p93. In both groups of patients, the T cell lines frequently recognized OspB, and only occasionally recognized OspC, p39, and p93. In contrast, OspA was preferentially recognized by T cell lines from patients with treatment-resistant arthritis, but only rarely recognized by T cell lines from patients with treatment-responsive arthritis (odds ratio 28.4, 95% confidence interval 9.2-87.8, p < 0.005). These results are compatible with the hypothesis that the T cell response to B. burgdorferi OspA is involved in the pathogenesis of treatment-resistant Lyme arthritis.

Adult↗
PubMed1993

T cell unresponsiveness in lepromatous leprosy.

T lymphocytes from patients with lepromatous leprosy are anergic to M. leprae antigens. The mechanisms which induce and maintain this antigen specific T cell unresponsiveness in lepromatous leprosy have been the subject of intensive research. Recent insights from work on T cell recognition of antigen, cytokines, and T cell subsets have considerably enhanced the understanding of the immunopathology of lepromatous leprosy.

Antigens, Bacterial↗
PubMed1992

Silencing of immunodominant epitopes by contiguous sequences in complex synthetic peptides.

We have previously shown that the T cell response to the synthetic peptide cI12-26:NP365-380 (covalently linked epitopes of lambda repressor (cI) and influenza A nucleoprotein (NP) polypeptides) requires amino acid sequences located in the junctional region between the cI12-26 and NP365-380 epitopes in the H-2d and H-2k haplotypes. In this study, we show that the dominant epitope of cI12-26:NP365-380 in H-2b mice is also located within the junctional region of the peptide, indicating that the same amino acid sequence is immunodominant in three different H-2 haplotypes. Based on results using fixed APC, there was no qualitative difference in epitope recognition due to antigen processing. In addition, antigen presentation by APC expressing mutant I-A molecules constructed by hemiexon shuffling of regions of the molecule containing primarily beta sheet or alpha helix showed that many different substitutions were permissive for at least one of the T hybridomas. More importantly, however, when the junctional sequences are covalently linked in composite synthetic peptides containing additional previously defined T cell epitopes, antigenicity of the immunodominant junctional region was silenced and a new epitope assumed immunodominance. Thus, immunodominance does not correlate with the primary amino acid sequence of the potential epitope. Instead, the immunodominant epitope is determined by complex interactions among the epitopes, which most likely depend on the structural conformation of the composite peptide.

Amino Acid Sequence↗
PubMed1991

Pertussis toxin prevents the induction of peripheral T cell anergy and enhances the T cell response to an encephalitogenic peptide of myelin basic protein.

In a murine model of T cell-mediated autoimmune disease, experimental autoimmune encephalitis (EAE), 80% of all encephalitogenic T cell clones in H-2u mice use the V beta 8.2 TCR element. To induce EAE in susceptible strains of mice either heat-killed Bordetella pertussis organisms or Bordetella pertussis toxin (PT) must be injected in addition to Ag in CFA. We investigated the mechanisms by which PT facilitates the induction of EAE. Our data show, that PT interferes with the induction of Ag-induced peripheral T cell anergy. Furthermore it has a specific adjuvanticity for the autoantigen pAc1-11 in vivo and acts as a selective mitogen in vitro. We also tested the hypothesis that PT is a bacterial superantigen that specifically expands the V beta 8.2+ subset of T cells, thereby expanding the encephalitogenic T cell clones that are contained in this subset, so that the number of autoreactive T cells is brought over a critical threshold, necessary to induce autoimmune disease. Our data show that PT is not a superantigen. Staphylococcal enterotoxin B, a V beta 8.2-specific superantigen, does not enhance the immune response to the encephalitogenic peptide.

Adjuvants, Immunologic↗
PubMed1991

Immunodominance: intramolecular competition between T cell epitopes.

We have used an approach of linking previously characterized T cell epitopes into immunologically complex synthetic peptides in order to investigate the mechanism of immunodominance. Our results show that first, cI12-26 is highly dominant following immunization with the lambda repressor (cI) protein, but is a minor epitope in the context of the cI:NP peptide. In contrast, the dominant epitope in response to the cI:NP peptide is a new junctional epitope, which is composed of sequences derived from both the cI and influenza nucleoprotein (NP) segments of the composite peptide. Second, T cell recognition of cI:NP is not significantly altered by Ag processing, based on results from glutaraldehyde-fixed APC. Third, the relative affinities of cI and cI:NP for MHC binding are similar, based on in vitro competition, excluding competition at the level of MHC binding as the determinant of immunodominance. Taken together, these results are consistent with the hypothesis that immunodominance of cI:NP is determined by peptide conformation, which affects the configuration of peptide binding to MHC, thus altering T cell recognition. In conclusion, immunodominance is not simply a function of the primary amino acid sequence, but is a function of the context of the epitope within the protein molecule.

Amino Acid Sequence↗
PubMed1990

Heterosexual transmission of HIV in hemophiliacs.

Of 686 hemophiliacs who are being treated at our institution, 402 (59%) are HIV-sero-positive. One hundred seventy-eight heterosexual partners of HIV-infected hemophiliacs have been serologically examined; 19 (11%) are HIV-positive. So far none of the seropositive partners suffers from ARC or AIDS. The rate of heterosexual transmission of HIV is statistically significantly correlated with the CD4+ count of the HIV-infected index patient. No such correlation was found with the index patient's clinical stage or the isolation of HIV from the index patient's blood. Of 39 seronegative female partners who were investigated clinically and immunologically, 17 showed pathologically increased numbers of CD8+ counts. In one case, HIV was transmitted from a female patient with von Willebrand's disease to her husband. As compared to other groups at risk for AIDS, the rate of heterosexual HIV transmission is comparatively low in hemophiliacs. The exact reason for this difference is not yet known. The relevance of the immunopathological findings in seronegative sexual partners of hemophiliacs also remains to be determined.

Adult↗
PubMed1989

Natural history of HIV-infection in hemophiliacs: clinical, immunological, and virological findings.

At our institution 686 hemophiliacs are being treated. Of them 402 (59%) are anti-HIV-seropositive. The general use of heat-treated clotting factor products was begun in July 1983, and from May 1984 all patients exclusively used heat-treated clotting factors. Thus, one can assume that infection occurred no later than early 1984 in our patients. Since December 1985 HIV-positive hemophiliacs have regularly been clinically and immunologically examined. Most of the 306 patients who could be investigated were clinically symptom-free at the time of their first visit. However, 45 patients have developed AIDS from 1982 through August 1988. The mean survival time of hemophiliacs with AIDS is less than 6 months. In 36% of those 274 patients who have been followed for a mean period of 14 months the clinical stage of the disease worsened by at least one stage according to the classification system proposed by the Centers for Disease Control. We did not find a correlation between clotting-factor consumption during the years 1984-1986 and the actual clinical stage of the patients. Virus isolation from peripheral blood lymphocytes (PBIs) answered the question whether anti-HIV seropositive hemophiliacs are not only immunized but really infected in many more cases than those revealed by detection of p24 antigen or decline of p24 antibody. Positive viral culture correlated strongly with a drop in CD4+ lymphocytes under the level of 400/microliters. However, HIV could not be cultured regularly in advanced cases, suggesting that virus replication in PBLs is not necessarily the cause of depletion of T-helper cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

[Arrhythmogenic effect of flecainide--treatment with i.v. magnesium].

We report on a 46-year-old woman with ventricular tachycardia and ventricular fibrillation after starting antiarrhythmic drug therapy with flecainide. The flecainide acetate plasma levels were always in the normal range. A successful therapeutical intervention was induced with two i.v. applications of 1,000 mg magnesium glutamate. A persistent suppression of ventricular rhythm disturbance was accomplished by continuous i.v. application of 4 mg magnesium glutamate/min.

Electrocardiography↗