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R Batchelor

Publications and source records attributed to R Batchelor.

At least 19 recordsLinked to original sources
PubMed2000

Significant frequencies of T cells with indirect anti-donor specificity in heart graft recipients with chronic rejection.

BACKGROUND: The purpose of this study was to determine whether T cells with indirect allospecificity could be detected in heart transplant recipients with chronic rejection. METHOD AND RESULTS: Human T-cell clones were used to determine the most effective way to deliver major histocompatibility complex alloantigens for indirect presentation. Seven allograft recipients with evidence of progressive, chronic rejection were selected. Four heart graft recipients with no evidence of chronic rejection were used as controls. Peripheral blood T cells and antigen-presenting cells from the recipients were cultured with frozen/thawed stored donor cells or major histocompatibility complex class I-derived synthetic peptides in limiting dilution cultures and then compared with controls using tetanus toxoid and frozen/thawed third-party cells with no human leukocyte antigens in common with the donor. In 5 of 7 patients analyzed who had chronic rejection, elevated frequencies of T cells with indirect, anti-donor specificity (iHTLf) were detected. No such elevated iHTLf were detected in recipients without chronic rejection. DISCUSSION: iHTLf can be obtained from human transplant recipients, which supports the contention that the indirect pathway is involved in chronic transplant rejection.

Animals↗
PubMed2000

Ceramide kinase.

Explore the source record for details and available documents.

Ceramides↗
PubMed1998

Assessment of the contribution that direct allorecognition makes to the progression of chronic cardiac transplant rejection in humans.

BACKGROUND: Two populations of T cells contribute to allograft rejection. T cells with direct allospecificity are activated after recognition of intact MHC alloantigens displayed at the surface of donor passenger leukocytes carried within the graft. In contrast, T cells with indirect allospecificity recognize donor alloantigens as processed peptides associated with self (recipient)-MHC class II molecules. In small animal models of transplantation, direct pathway T cells dominate the acute rejection process and are rendered tolerant to the graft after the loss of donor passenger leukocytes. It has been argued that indirect pathway T cells contribute substantially to continual graft damage after passenger cell loss. The purpose of this study was to determine whether donor-specific tolerance could be detected in T cells with direct anti-donor allospecificity in human heart transplant recipients after prolonged graft residence. METHODS AND RESULTS: Alloreactive helper (HTLf) and cytotoxic (CTLf) T cells were enumerated by use of limiting dilution analysis. These assay systems were refined to make them specific for the direct pathway of allorecognition and more sensitive in the case of the HTLf assay. Recipient:anti-donor frequencies were generated in 10 long-term recipients of heart grafts with progressive chronic rejection and compared with those against equivalently HLA mismatched recipient:third-party controls. For HTLf, direct pathway donor-specific hyporesponsiveness was detected in 5 of the 10 recipients (HTLf<1:100,000). Of these 5 recipients, 4 also had low anti-donor CTLf (<1:100,000). In the 5th recipient, although the CTLf was >1:100,000, it was significantly lower than that estimated against the third-party control. CONCLUSIONS: Donor-specific hyporesponsiveness is demonstrated in 50% of recipients in both the HTLf and CTLf compartments of the direct alloresponse. Direct allorecognition therefore appears unlikely to be responsible for the progression of chronic rejection, implicating indirect allorecognition as the predominant immunological driving force. Furthermore, these data have potential implications for graft outcome, adjustment of immunosuppression, and recipient monitoring.

Antibody Specificity↗
PubMed1998

Evaluation of an indirect immunofluorescence assay for the detection of Leishmania promastigotes and amastigotes in sand flies and lesion fluid aspirates.

Rabbit monospecific antibody Leishmania major surface glycoprotein (gp63) was used in an indirect immunofluorescence assay (IFA) to identify promastigotes and amastigotes from sandflies and lesion fluid aspirates, respectively. Anti-gp63 fluoresced the entire periphery and flagella of promastigotes of different Leishmania species at dilutions to 1:50. Promastigotes were distinctively demonstrated in whole infected sandfly homogenate for 17 days post-infection. Amastigotes from lesion aspirates of infected BALB/c mice and from a human cutaneous leishmaniasis case were also fluoresced by the antibody. This technique could prove to be especially useful in arthropod vector surveillance efforts in which detection of the pathogen is as important as speciation of the sand fly vector.

Animals↗
PubMed1997

Measurement of cytotoxic T lymphocyte precursor frequencies reveals cryptic HLA class I mismatches in the context of unrelated donor bone marrow transplantation.

BACKGROUND: In this large, two-center study, 260 cytotoxic T lymphocyte precursor (CTLp) frequency assays, performed to assess patient-donor compatibility, were analyzed in relation to the degree of HLA matching. METHODS: While the tissue-typing techniques used at the Royal Postgraduate Medical School (RPMS) and Anthony Nolan Bone Marrow Trust (ANBMT) differ, the results of the analyses on the two sites are analogous, with high CTLp frequencies (>1:100,000) in 42% and 41% of recipient-donor pairs, respectively. RESULTS: Recipient-donor combinations with class I mismatches and class II identity were associated with high CTLp frequencies (collectively 83% vs. 17% low CTLp). This correlation was not as strong in pairs where class II mismatches were demonstrated (61% high vs. 39% low). Despite using different matching procedures, the RPMS and ANBMT both show that 32% of the "perfectly" matched pairs (i.e., where no mismatch was detected by any of the techniques used here) had high frequencies of recipient-specific CTLp. CONCLUSIONS: The failure of conventional methods to identify such a level of histoincompatibilities indicates that the CTLp assay has an important role in the selection of unrelated donors for bone marrow transplantation.

Bone Marrow Transplantation↗
PubMed1997

Optimizing a limiting dilution culture system for quantifying the frequency of interleukin-2-producing alloreactive T helper lymphocytes.

BACKGROUND: The development of sensitive, specific, and reproducible techniques to quantify T cells with direct allospecificity has potential applications in the selection of bone marrow donors and in the monitoring of the antidonor alloresponse in patients after organ transplantation. Such data may provide an objective basis for altering existing immunosuppression, monitoring novel antirejection therapies, and predicting long-term graft outcome. We have previously published a correlation between donor antirecipient T helper frequencies (HTLf) and the severity of acute graft-versus-host disease after bone marrow transplantation. Using the same assay protocol, we have described the development of donor-specific hyporesponsiveness in a proportion of renal transplant recipients. However, several imperfections existed in the protocols used in these studies. Cellular interactions within the stimulator and the responder cell populations, and back stimulation of T cells within the stimulator cell population, could give rise to extraneous interleukin-2 and alter the validity or estimation of derived recipient antidonor HTLf. METHODS: Using peripheral blood mononuclear cells as the responding population and splenic mononuclear cells as the stimulating population, we have examined the possible effects of these cellular interactions on the results of limiting dilution analysis assays for HTLf measurement. RESULTS: These interactions have the ability to alter the validity or estimation of HTLf. We show that by depleting the responder population of HLA class II+ cells and depleting T cells from the stimulating population, these interactions are effectively abrogated. CONCLUSIONS: On the basis of the findings reported here, we describe an optimized HTLf assay which is sensitive, specific, and reproducible. This has obvious applications in the analysis of alloimmune responses in transplantation.

Bone Marrow Transplantation↗
PubMed1996

Malaria among United States troops in Somalia.

PURPOSE: United States military personnel deployed to Somalia were at risk for malaria, including chloroquine-resistant Plasmodium falciparum malaria. This report details laboratory, clinical, preventive, and therapeutic aspects of malaria in this cohort. PATIENTS AND METHODS: The study took place in US military field hospitals in Somalia, with US troops deployed to Somalia between December 1992 and May 1993. Centralized clinical care and country-wide disease surveillance facilitated standardized laboratory diagnosis, clinical records, epidemiologic studies, and assessment of chemoprophylactic efficacy. RESULTS: Forty-eight cases of malaria occurred among US troops while in Somalia; 41 of these cases were P falciparum. Risk factors associated with malaria included: noncompliance with recommended chemoprophylaxis (odds ratio [OR] 2.4); failure to use bed nets (OR 2.6); and failure to keep sleeves rolled down (OR 2.2). Some patients developed malaria in spite of mefloquine (n = 8) or doxycycline (n = 5) levels of compatible with chemoprophylactic compliance. Five mefloquine failures had both serum levels > or = 650 ng/mL and metabolite:mefloquine ratios over 2, indicating chemoprophylactic failure. All cases were successfully treated, including 1 patient who developed cerebral malaria. CONCLUSIONS: P falciparum malaria attack rates were substantial in the first several weeks of Operation Restore Hope. While most cases occurred because of noncompliance with personal protective measures or chemoprophylaxis, both mefloquine and doxycycline chemoprophylactic failures occurred. Military or civilian travelers to East Africa must be scrupulous in their attention to both chemoprophylaxis and personal protection measures.

Anti-Bacterial Agents↗
PubMed1994

Anergic T cells as suppressor cells in vitro.

T cell-mediated suppression is an established phenomenon, but its underlying mechanisms are obscure. An in vitro system was used to test the possibility that anergic T cells can act as specific suppressor cells. Anergic human T cells caused inhibition of antigen-specific and allospecific T cell proliferation. In order for the inhibition to occur, the anergic T cells had to be specific for the same antigen-presenting cells (APCs) as the T cells that were suppressed. The mechanism of this suppression appears to be competition for the APC surface and for locally produced interleukin-2.

Antigen-Presenting Cells↗
PubMed1994

Failure of correlation between B7 expression and activation of interleukin-2-secreting T cells.

It is well established that triggering interleukin-2 (IL-2) secretion by helper T cells requires the T cell to receive at least two discrete signals. One signal is transduced by the CD3 complex, usually as the result of T cell receptor (TcR) occupancy, the second, or co-stimulatory, signal involves a non-cognate interaction between cell surface accessory molecules on the antigen-presenting cell (APC) and the T cell. A molecular interaction that has been implicated in the provision of co-stimulatory signals is that between B7/BB1 on the APC and its ligands, CD28 and CTL-A4 on the T cell. We have studied the ability of HLA-class II antigen-positive human T cells and a population of DR1-expressing transfected human fibroblasts to stimulate a proliferative response by human T cell clones, and by freshly isolated peripheral blood T cells. Despite their high levels of B7 expression, the T cell clones, were unable to induce proliferation or IL-2 secretion by DR-restricted, antigen-specific T cells. In contrast, the DR1-expressing transfectants, that were B7 negative, induced a strong proliferative response. When these two populations of DR-expressing cells were used to stimulate a primary alloresponse the results were reversed, in that the T cell clones induced a strong alloresponse but the transfected fibroblasts induced no proliferation. These results suggest that the expression of B7 may be necessary for costimulation of unprimed T cells, but not of established T cell clones. Furthermore the data show that the expression of B7 by an APC does not necessarily lead to IL-2 production or protection from the induction of tolerance. The mechanisms responsible for the inability of these T cells to provide full activation signals when used as APC is currently under investigation.

Antigen-Presenting Cells↗
PubMed1994

Threat of hepatitis E virus infection in Somalia during Operation Restore Hope.

In support of Operation Restore Hope, the United States military established a diagnostic laboratory for infectious diseases, the Joint Forward Laboratory, in Mogadishu, Somalia. Because sporadic hepatitis due to unknown causes was a frequent problem, staff members of the Joint Forward Laboratory evaluated 31 Somalis, five displaced Ethiopians, and three Western relief workers who had acute clinical hepatitis. Patients lived in multiple locations in Somalia--Mogadishu, Baidoa, and Merca--and became ill between December 1992 and February 1993. IgM antibody to hepatitis A virus was found in one English relief worker, and IgM antibody to hepatitis E virus was found in 20 (65%) of 31 Somalis, two (40%) of five Ethiopians, and two (67%) of three Western relief workers. No patient had evidence of acute hepatitis B, malaria, yellow fever, or other arbovirus infections. These data indicate that hepatitis E virus--the major cause of enterically transmitted non-A, non-B hepatitis--was a common cause of acute sporadic hepatitis in Somalia during the initial stages of Operation Restore Hope.

Disease Outbreaks↗
PubMed1992

A rapid limiting dilution assay for measuring frequencies of alloreactive, interleukin-2-producing T cells in humans.

A limiting dilution analysis (LDA) has been established which measures the total numbers of alloreactive interleukin-2 (IL-2)-secreting T cells in human peripheral blood mononuclear cells (PBMC). A significant advantage over most previous LDA is that the assay may be completed in approximately 48 h since an IL-2-dependent 'indicator' cell line is used to reduce assay time. Results are reproducible and correlate with the degree of HLA class II antigenic disparity between responder and stimulator cells. Use of both PBMC and Epstein-Barr virus-transformed B lymphoblastoid cell lines (B-LCL) as stimulator cells permits estimation of the frequency of Epstein-Barr virus-specific T cells in different responder individuals. A modification of the assay may also be used to measure the frequencies of 'primed' alloreactive cells, i.e., those alloreactive cells which have previously encountered their specific stimulating alloantigen. Use of the assay in the clinical context of bone marrow and renal transplantation is discussed.

Animals↗
PubMed1992

Use of a murine T-cell hybridoma expressing human T-cell receptor alpha- and beta-gene products as a tool for the production of human T-cell receptor-specific monoclonal antibodies.

We describe the production of mouse monoclonal antibodies specific for the human TcR using as the immunogen transfected murine T-cell hybridoma cells coexpressing mouse CD3 with human Jurkat TcR alpha and beta chains. The shortage of monoclonal antibodies (mAbs) specific for the human TcR-V alpha and V beta families reflects the difficulties in their production by conventional methods using whole human T cells or purified soluble receptors as immunogens. As an alternative strategy to circumvent these difficulties, we have generated a transfected mouse T-cell line expressing a human (Jurkat) TcR alpha beta dimer in a complex with mouse CD3. The parental mouse T-cell line, TG40, is a cell surface TcR-negative, cytoplasmic CD3-positive variant of the mouse T-cell hybridoma 2B4. The human-TcR alpha beta expressing mouse transfectant was used to immunize mice with the same genetic background as the parent mouse T-cell line, and a human TcR-specific response was successfully achieved. MAb-producing hybridomas were generated by fusing spleen cells from the immunized mice with the mouse myeloma cell line NSO. Of 124 hybridoma supernatants screens, 72 showed reactivity to the human T-cell line Jurkat. Twenty-four of the hybridomas producing human (Jurkat) TcR-specific antibodies were cloned and screened for reactivity to Jurkat TcR. Several IgG2b and IgM mAbs specific for the Jurkat T cell line were selected on the basis of their ability to modulate surface CD3 expression on Jurkat cells. Most of the antibodies do not stain other TcR-expressing human T cell leukemia cell lines, implying specificity for the variable domains of the Jurkat TcR.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Orthotopic liver transplantation for hepatic GVHD following allogeneic BMT for chronic myeloid leukaemia.

A 21-year-old man who had an HLA-identical sibling donor BMT for chronic myeloid leukaemia developed grade IV acute GVHD of the liver that was unresponsive to corticosteroids and anti-IL2 receptor monoclonal antibody. He was treated with an orthotopic liver transplant and is currently well 6 months later with normal liver function and no evidence of GVHD in the transplanted liver.

Adult↗
PubMed1992

[Outbreak of paratyphoid fever among Peruvian naval personnel].

A retrospective epidemiological study was conducted in connection with an outbreak of paratyphoid fever at a Peruvian naval installation in Callao. The study sought to determine the magnitude of the outbreak, the source of infection, the attack rates, the persistence of bacilli excretion, and the clinical picture of the disease. The source of Salmonella paratyphi B infection had been a meal of chicken and rice served to around 400 members of the naval police. Over a period of three weeks, 21 persons were hospitalized and 52 received outpatient treatment at the naval hospital. In addition, through a questionnaire it was revealed that 86 unreported cases of diarrhea related to the outbreak had occurred. The most common clinical manifestations were fever, headache, weakness, anorexia, abdominal pain, and diarrhea. The general attack rate was 39.8%. In a follow-up survey carried out 37 days after exposure, fecal cultures indicated that 8.5% of the persons affected continued to excrete the microorganism. The high rates of attack and transmission of S. paratyphi B in this outbreak point up the considerable pathogenicity and virulence of some strains of the microorganism and their impact on public health. It is suggested that preventive measures be taken at naval and other similar installations, including the education of workers who handle and prepare food, in order to ensure proper hygiene.

Adult↗
PubMed1991

Optimising a limiting dilution culture system for quantitating frequencies of alloreactive cytotoxic T lymphocyte precursors.

We have developed a limiting dilution assay for estimating the frequencies of allo-MHC reactive cytotoxic T lymphocyte precursors (CTL-p) in peripheral blood. The culture conditions were optimised in order to give maximum sensitivity while at the same time maintaining a high degree of specificity. While the addition of filler cells, interleukin-1 and interleukin-4 were unnecessary, the addition of interleukin-2 (IL-2) was crucial for optimal expansion of the CTL-ps. However, excess exogenous IL-2 was found to give rise to nonspecific cytotoxicity, and 5 U/ml final concentration of recombinant IL-2 added on Days 3 and 6 was optimal. The establishment of baseline control cultures for determining positivity and negativity of the test cultures is discussed. Using this modified assay system, we demonstrated that the culture conditions fulfil "single hit" criteria and that the assay is highly specific.

Cell Differentiation↗
PubMed1991

Limited regions of the alpha 2-domain alpha-helix control anti-A2 allorecognition: an analysis using a panel of A2 mutants.

The regions of the HLA-A2 molecule controlling anti-A2 alloreactivity were explored using naturally occurring allelic variants of HLA-A, and a panel of transfectants expressing the products of A2.1 genes that had been mutated at multiple positions encoding residues in the alpha 2 domain alpha-helix. As a means of detecting distant conformational effects, these altered A2.1 molecules were also examined serologically. Amino acid substitutions at the carboxy-terminal end of the alpha 2 domain alpha-helix led to diminished staining with the monoclonal antibody (mAb) MA2.1. The epitope for this antibody has previously been mapped to the alpha 1 domain alpha-helix (residues 62-65). This suggests that interdomain contacts may cause conformational alteration, and that mutants can have distant, as well as local effects. Of the 24 positions where substitutions were made, only six led to loss of the anti-A2 alloresponse by the three clones and three lines that were tested. In addition, the mutations that altered the MA2.1 epitope, located on the alpha 1 domain alpha-helix, did not inhibit allorecognition. This suggests that a limited number of regions on the A2.1 molecule are responsible for allodeterminant expression. The most influential substitutions were those at positions 152, 154, 162, and 166. It is notable that three of these are predicted to be T-cell receptor (Tcr)-contacting residues, and one (152) to contribute to peptide binding. These results suggest that the specificity of alloreactive T cells is determined by exposed polymorphisms, directly contacted by the Tcr, and by concealed polymorphisms which influence peptide binding.

Cell Line↗
PubMed1991

Generation and characterization of an HLA-DR alpha-specific monoclonal antibody using L-cell transfectants expressing human and mouse class II major histocompatibility dimers.

Among the HLA-DR-specific monoclonal antibodies (mAbs) that have been characterized previously, there is a marked shortage of DR alpha chain-specific mAbs which stain unfixed cells. This may result from the high degree of sequence similarity between the alpha 1 domains of HLA-DR and H-2E leading to a state of cross-tolerance to DR alpha in H-2-expressing mice. BALB/b (E-negative) mice were immunized with DR1-transfected mouse L cells. The chain specificity of the resulting DR-specific mAb was determined using a panel of transfectants expressing hybrid mouse/human class II heterodimers. A DR alpha-specific mAb was generated which was capable of immunoprecipitating DR alpha beta dimers and inhibiting the anti-DR alloresponse of human T-cell clones. The present study demonstrates that, with the selection of a suitable recipient strain, transfectants can be useful in the generation and definition of chain-specific mouse mAbs.

Animals↗