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T H The

Publications and source records attributed to T H The.

At least 37 records · Page 2Linked to original sources
PubMed1999

Cytomegalovirus pneumonitis after kidney transplantation is not caused by plugging of cytomegalic endothelial cells only.

In addition to life-threatening pneumonia, cytomegalovirus (CMV) may also cause subclinical pulmonary dysfunction after kidney transplantation. To investigate the role of plugging of cytomegalic endothelial cells in the pulmonary capillary bed, we prospectively determined specific carbon monoxide diffusion capacity (KCOc) and its components: the pulmonary diffusing membrane factor (Dm) and pulmonary capillary blood volume (Vcap) before and during CMV infection in 13 kidney transplant recipients and 13 controls. During CMV infection, mean KCOc decreased significantly by 28 % of the initial value (mean KCOc 79 vs 109; P < 0.005 ) due to a decrease in both Vcap and Dm. The KCOc in controls showed a significantly smaller decrease due to a slightly lower Vcap. We conclude that kidney transplant recipients with CMV infection have significant pulmonary diffusion disturbances due to a combination of lower Vcap and lower Dm. The most likely explanation for this phenomenon is a local inflammatory process due to CMV and not plugging of cytomegalic endothelial cells only.

Adolescent↗
PubMed1999

The central role of monocytes in the pathogenesis of sepsis: consequences for immunomonitoring and treatment.

Despite important advances in critical care medicine during the last two decades, the mortality rate of sepsis has remained high, probably because the pathogenesis of sepsis is still incompletely understood. Recent studies have shown that sepsis is a bimodal entity. The first phase is characterized by the systemic release of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-alpha), interleukin-1 (IL-1), and IL-8, and by activation of the complement and coagulation cascades. In the second phase, anti-inflammatory mediators such as transforming growth factor-beta (TGF-beta), IL-10 and prostaglandin E2 (PGE2) may be released in an effort to counteract ongoing inflammation. Depending whether the pro- or anti-inflammatory response predominates, sepsis results in a systemic inflammatory response syndrome (SIRS), or a compensatory anti-inflammatory response syndrome (CARS). So far, most efforts to intervene in the immunopathogenesis of sepsis have been directed at the pro-inflammatory response. None of these interventions has been shown to improve the prognosis of sepsis, possibly because many patients were already in a state in which anti-inflammatory responses dominated. Recently, it has been shown that decreased expression of HLA-DR on monocytes in patients with sepsis constitutes a marker for CARS. We suggest that HLA-DR expression on monocytes might constitute a useful indicator of the immunological status of the individual patient with sepsis and a guide for treatment. Patients with CARS, as manifested by low HLA-DR expression, might benefit from immunostimulants, while patients with SIRS and normal or high monocyte HLA-DR expression should receive treatment directed to interfere with pro-inflammatory pathways.

Biomarkers↗
PubMed1999

Comparison of the Murex Hybrid Capture CMV DNA (v2.0) assay and the pp65 CMV antigenemia test for the detection and quantitation of CMV in blood samples from immunocompromised patients.

BACKGROUND: Presently the semiquantitative pp65 cytomegalovirus (CMV) antigenemia test on white blood cells is often used for monitoring transplant patients for the appearance of active CMV infections. However, the need for immediate processing of the specimens and the lack of interlaboratory standardization of the test may sometimes be a disadvantage. OBJECTIVE: The aim of this study was to investigate the value of the recently developed second version of the Murex Hybrid Capture (MHC) CMV-DNA assay (v 2.0) in comparison with the CMV-pp65 test. The MHC CMV-DNA assay is a quantitative solution hybridization antibody capture assay, using alkaline phosphatase conjugated antibodies and a chemiluminescent substrate. STUDY DESIGN: 248 EDTA blood samples from 33 renal transplant patients and 32 samples from 22 other immunocompromised patients were tested by both the MHC CMV-DNA assay and the CMV-pp65 test. RESULTS: The qualitative ( + or -) results of both tests showed an overall concordance of 81.4%. Calculations on the basis of discordancy analyses showed that the sensitivity, the specificity, and the positive and negative predictive values were 87.7, 98.3, 98.6, 85.2% for the MHC CMV-DNA assay and 76.6, 100, 100, 75.5% for the CMV-pp65 test. Comparison of the quantitative results of both tests systems showed a correlation coefficient of 0.837. In addition, retesting of 50 samples with the MHC-CMV-DNA assay showed an excellent reproducibility with a correlation coefficient of 0.992. All patients which were tested regularly (at least five samples) became either positive with both tests or with none of them. Neither test system detected CMV significantly earlier than the other one. Both tests became strongly positive in all transplant patients with symptomatic CMV infections, and both tests showed a rapid decline of CMV during subsequent antiviral treatment. CONCLUSION: The quantitative Murex Hybrid Capture CMV-DNA assay (v 2.0) may become a valuable additional tool in CMV diagnosis. Further studies will be needed to support this preliminary judgement.

AIDS-Related Opportunistic Infections↗
PubMed1999

Low HLA-DR expression on peripheral blood monocytes predicts bacterial sepsis after liver transplantation: relation with prednisolone intake.

Bacterial sepsis remains a frequent complication after liver transplantation. We previously reported the results of a pilot study that suggested that low expression of HLA-DR on monocytes is a predictive marker for the occurrence of sepsis. We have studied the value of this marker in an additional cohort of patients, and have analyzed the relation of HLA-DR expression with the use of immunosuppressive agents. 20 adult liver transplantation patients were prospectively monitored during the first 4 weeks after transplantation. All were treated according to standard protocols. The percentage of monocytes expressing HLA-DR was measured by flow cytometry. In addition, the effects of incubation of monocytes with prednisolone in vitro on the expression of HLA-DR was determined in 7 healthy volunteers. Seven patients developed bacterial sepsis after a median 15 (range 10-20) days after transplantation. HLA-DR expression was significantly lower in these patients on days 7, 14, 21, and 28 after transplantation compared with non-septic patients. The percentage of HLA-DR positive monocytes was 30% or less, 3 (1-8) days before onset of sepsis. On day 7 after transplantation, HLA-DR expression on 50% or less of monocytes had a positive predictive value for sepsis of 71%, whereas the negative predictive value was 85%. Patients who developed sepsis received significantly more prednisolone. Incubation with prednisolone in vitro lowered the expression of HLA-DR in a dose-dependent manner. We conclude that low HLA-DR expression on monocytes is a marker for a high risk of subsequent sepsis in liver transplantation patients. This high risk may be (at least partly) related to the dose of prednisolone.

Adolescent↗
PubMed1999

Plasma lactoferrin levels are decreased in end-stage AIDS patients.

The antimicrobial protein lactoferrin (Lf) is present in plasma and in mucosal secretions. Using ELISA we analysed plasma and saliva of HIV-infected patients, patients with AIDS, and healthy controls for the presence of secreted Lf. The plasma Lf levels of AIDS patients (classification C3) were significantly lower (p < 0.001) as compared to asymptomatic and symptomatic HIV infected patients, or controls. In addition, plasma Lf levels closely correlated with neutrophilic granulocyte counts in the HIV-infected patients. Thus, basal plasma Lf levels are likely the result of Lf release by neutrophilic granulocytes. The Candida titres present in the oral cavity were determined in a part of the HIV-infected patient group. As it appeared, the presence of this opportunistic pathogen always coincided with low levels of salivary Lf levels. We conclude that Lf, as part of the nonspecific immune system, might play an important role in the first line of defense against opportunistic microbial infections in AIDS patients.

AIDS-Related Opportunistic Infections↗
PubMed1999

Immune response capacity after human splenic autotransplantation: restoration of response to individual pneumococcal vaccine subtypes.

OBJECTIVE: To evaluate features of general immune function, in particular the restoration of the humoral immune response to pneumococcal capsular polysaccharides, in humans undergoing a spleen autotransplantation after splenectomy because of trauma. SUMMARY BACKGROUND DATA: After splenectomy, patients have an increased risk of overwhelming infection or sepsis involving encapsulated bacteria such as pneumococci. The value of human spleen autotransplantation after splenectomy because of trauma has long been questioned. Mononuclear phagocyte system function appeared to be similar to that in splenectomized persons. The presence of specific antipneumococcal antibodies would allow other parts of the mononuclear phagocyte system, such as those in the liver, to phagocytose opsonized bacteria. METHODS: Ten consecutive patients undergoing splenectomy followed by autotransplantation were compared with the next 14 consecutive patients undergoing splenectomy alone. After a minimum of 6 months, the patients were vaccinated with 23-valent pneumococcal vaccine. Blood samples were taken at the time of vaccination and after 3 and 6 weeks for antipneumococcal capsular polysaccharides IgM and IgG enzyme-linked immunosorbent assay against types 3, 4, 6, 9, 14, and 23. Splenic regrowth was evaluated by scintigraphy. RESULTS: Surprisingly, several of the nonautotransplanted patients showed scintigraphic activity, indicating the presence of either accessory spleens or traumatic seeding (splenosis). Significant antibody titer increases (more than twofold) were found for both IgM and IgG in the autotransplanted patients. Splenectomized-only patients showed no significant increase in Ig levels in patients without splenic regrowth and partial improvement in patients with splenosis/accessory spleens. CONCLUSIONS: Considering this significant antipneumococcal antibody increase, spleen autotransplants can be expected to permit an adequate humoral response to pneumococcal infections and presumably also to other TI-2 antigens, and to protect against overwhelming postsplenectomy infection or sepsis.

Adolescent↗
PubMed1999

Humoral immune response to human cytomegalovirus in patients undergoing percutaneous transluminal coronary angioplasty.

Possible causal relations between prior human cytomegalovirus (HCMV) infection and atherosclerosis and between HCMV reactivation and restenosis after coronary angioplasty have been suggested. We investigated patterns of antibodies directed to HCMV in 112 patients undergoing percutaneous transluminal coronary angioplasty (PTCA) and in a group of sex- and age-matched controls (blood donors without evidence of atherosclerosis). Levels of antibodies to HCMV were measured by enzyme-linked immunosorbent assay (ELISA) of serum samples drawn before and 5 weeks after PTCA. To further differentiate the humoral immune response, we specifically tested antibody reactivity towards four single HCMV proteins (IE2, p52, pp150, and pp65) by recombinant ELISAs. We found that 73% of PTCA patients and 69% of sex- and age-matched controls were seropositive for HCMV (odds ratio, 1.2 [not significant]). The corresponding odds ratios for matched pairs ranged in the recombinant ELISAs from 1.2 to 1.4. Patients had more often high titers of anti-HCMV antibodies (11 versus 4%; odds ratio = 3.3 [0.9 to 15.2]; P = 0.052) and high titers of anti-pp150 antibodies (13 versus 4%; odds ratio = 6.0 [1.3 to 38.8]; P = 0.008). Anti-HCMV immunoglobulin M antibodies were not detected in any patient. There was no evidence of acute HCMV reactivation after PTCA, since the titers of antibodies to the investigated recombinant proteins did not increase at 5 weeks after PTCA. Our results show a limited association between prior HCMV infection and coronary artery disease. We infer that positive anti-HCMV titers are not a major risk factor at the time of disease manifestation. However, this study cannot rule out a possible role of HCMV at earlier stages of the atherosclerotic process. Recombinant ELISAs provide a valuable tool for investigating the antiviral immune response.

Adult↗
PubMed1999

Coronary angioplasty induces rise in Chlamydia pneumoniae-specific antibodies.

Chlamydia pneumoniae is frequently found in atherosclerotic lesions, and high titers of specific antibodies are associated with increased risk for acute myocardial infarction. However, a causative relation has not been established yet. We performed a prospective study of 93 patients undergoing percutaneous transluminal coronary angioplasty (PTCA) to investigate whether angioplasty influences Chlamydia-specific antibody titers and whether there is an association with restenosis. Blood samples were obtained before and 1 and 6 months after angioplasty. Antibodies against chlamydial lipopolysaccharide and against purified C. pneumoniae elementary bodies were measured by enzyme-linked immunosorbent assay (ELISA). After angioplasty, the prevalence of antibodies to lipopolysaccharide rose from 20 to 26% for immunoglobulin A (IgA), from 53 to 64% for IgG, and from 2 to 7% for IgM (P = 0.021, 0.004, and 0.046, respectively). There was a rapid increase of mean antibody titers of all antibody classes within 1 month of PTCA. During the following 5 months, antibody titers decreased slightly but were still higher than baseline values. Results of the C. pneumoniae-specific ELISA were essentially the same. The rise of anti-Chlamydia antibodies was not caused by unspecific reactivation of the immune system, as levels of antibodies against cytomegalovirus did not change. Neither seropositivity nor antibody titers were related to restenosis. However, increases in mean IgA and IgM titers were restricted to patients who had suffered from myocardial infarction earlier in their lives. In conclusion, we show that PTCA induces a stimulation of the humoral immune response against C. pneumoniae. These data support the idea that plaque disruption during angioplasty might make hidden chlamydial antigens accessible to the immune system.

Adult↗
PubMed1999

Overcoming the problem of cytomegalovirus infection after organ transplantation: calling for Heracles?

Although diagnosis of CMV infections and treatment of CMV disease with effetive antiviral drugs have become much easier, the persistent problem of CMV infection after solid-organ transplantation still requires solid knowledge of the pathophysiology of its clinical manifestations in order to minimize the impact of CMV infections in the future. The complex symptomatology of CMV infection after solid-organ transplantation is reviewed as well as some of the new theories attempting to explain the myriad of symptoms seen after transplantation.

Cytomegalovirus Infections↗
PubMed1999

Towards standardization of the human cytomegalovirus antigenemia assay.

The Human Cytomegalovirus antigenemia (HCMV-Agemia) test has been accepted worldwide as a clinical tool in the diagnosis and management of HCMV-associated syndromes in immunocompromised patients. The many modifications proposed since the first description by our laboratory make standardisation of the HCMV-Agemia assay necessary to enable multicenter clinical trials. We report the initial work for standardization of the HCMV-Agemia assay. A standard protocol is proposed, the optimal distribution conditions are investigated and the results of the shipment of positive and negative test slides as well as of two sets of coded internal standard slides are discussed. The main conclusions are that standard slides can be distributed at room temperature and that the results of participating laboratories with the coded internal standard slides were strikingly similar in spite of differences in HCMV-Agemia protocols used by participating laboratories.

Antibodies, Monoclonal↗
PubMed1998

Donor-specific hyporeactivity after liver transplantation: prominent decreases in donor-specific cytotoxic T lymphocyte precursor frequencies independent of changes in helper T lymphocyte precursor frequencies or suppressor cell activity.

BACKGROUND: The development of immunological donor-specific hyporeactivity may account for the low incidence of chronic rejection after clinical liver transplantation. We investigated whether hyporeactivity commonly develops after liver transplantation by analyzing precursor frequencies of donor-reactive cytotoxic (CTLp) and helper (HTLp) T lymphocytes and mixed lymphocyte culture (MLC) reactivity in liver allograft recipients. We further studied whether CTLp hyporeactivity correlated with changes in donor-specific HTLp frequencies or suppressor cell activity. METHODS: CTLp and HTLp frequencies and MLC reactivity against donor and third-party spleen cells were determined in pre- and posttransplantation peripheral blood samples from 18 recipients with good graft function 2 years after transplantation. By mixing posttransplantation samples (with "putative" suppressor cell activity) with pretransplantation samples (in which normal CTL activity with no suppressor cell activity is expected), the presence of suppressor cell activity in peripheral blood was analyzed. RESULTS: Two years after transplantation, all but one (94%) of the recipients had developed CTLp hyporeactivity as evidenced by reduced donor-specific CTLp frequencies. The development of hyporeactivity was not specific for any particular underlying disease. The occurrence of HTL hyporeactivity, however, was less frequent: 38% and 20% of recipients were HTLp and MLC hyporeactive, respectively. Decreases in CTLp frequencies did not correlate with decreased donor-specific HTL function or suppressor cell activity in peripheral blood samples. CONCLUSIONS: Donor-specific CTLp hyporeactivity can develop in the majority of liver allograft recipients, irrespective of underlying disease. Donor-specific HTL hyporeactivity, however, occurs infrequently. A reduction in donor-specific CTLp frequencies was found to be independent of changes in donor-specific HTLp or suppressor cell activity, suggesting that other mechanisms (e.g., clonal deletion) are operative in the reduction of donor-specific CTLp after liver transplantation.

Humans↗
PubMed1998

Quantitation of immunosuppression by flow cytometric measurement of the capacity of T cells for interleukin-2 production.

BACKGROUND: Methods to quantitate the effects of immunosuppressive drugs on immune reactivity might be helpful for monitoring immunosuppressive treatment. Cyclosporine (CsA) inhibits the induction of cytokine synthesis in T cells, and measurement of interleukin (IL)-2 production might constitute a parameter of this drug's effect. METHODS: We determined the percentages of CD4+ and CD8+ lymphocytes producing IL-2 upon stimulation by phorbol myristate acetate and calcium ionophore in whole blood culture, using immunostaining of intracytoplasmatic and membrane markers, followed by multiparameter flow cytometry. A total of 38 clinically stable transplant patients on various immunosuppressive protocols were studied. RESULTS: The percentage of CD4+ T cells producing IL-2 was strongly reduced in patients compared with healthy controls (23% [range, 3-68%] vs. 59.0% [range, 41-70%]; P=0.000035). The percentage of CD4+ T cells producing IL-2 was negatively correlated with the CsA level (Rc=-0.0821, P=0.00002297) but not with prednisolone or azathioprine doses. Fewer CD8+ T cells produced IL-2 in transplant patients compared with controls, but the difference failed to reach statistical significance. The percentage of CD8+ T cells capable of producing IL-2 was inversely correlated to CsA levels (Rc=-0.0375, P=0.0011). CONCLUSIONS: These data suggest that the functional effects of CsA in transplant recipients can be quantitatively determined and that the capacity of CD4+ T cells to produce IL-2 upon stimulation constitutes a functional parameter of CsA effects on the immune system. Prospective studies are required to determine whether this method is useful for clinical monitoring.

Adult↗
PubMed1998

Donor-specific immunological non-responsiveness after liver transplantation.

Since the rate of immunological losses of liver allograft after the immediate posttransplant period is much lower than in other organs, we studied the immune responses against donor HLA antigens in 18 patients with a good long-term outcome to determine whether the development of a state of immunological non-responsiveness to donor antigens might account for this favorable outcome. The reactivity against donor spleen cells was measured before and 2 years after transplantation. The reactivity in mixed lymphocyte culture (MLC) and the frequencies of cytotoxic T cell precursors (CTLp) were determined. Responses against third-party spleen cells were determined concurrently to exclude a generalized reduction of immunocompetence due to chronic immunosuppressive treatment. Before orthotopic liver transplantation, the majority of patients had normal T cell responses against donor antigens that were comparable to those against third-party antigens. Two years after transplantation, donor-specific MLC non-reactivity had developed in 10 of the 18 (56%) patients. In addition, 15 of 18 (83%) patients had developed donor-specific cytotoxic T cell (CTL) non-responsiveness; 2 had reduced numbers of CTLp against both donor and third-party cells, while the remaining patient had maintained reactivity against donor antigens. In conclusion, donor-specific non-responsiveness is present in the majority of patients 2 years after successful liver transplantation, but occurs predominantly at the CTL level.

Humans↗
PubMed1998

Quantification of immunosuppression by flow cytometric measurement of intracellular cytokine synthesis.

The availability of a method to measure the effects of drugs on immune reactivity should be helpful in optimizing treatment after organ transplantation. Since cyclosporine A (CSA) interferes with activation of T cells and cytokine synthesis, production of IL-2 and IFN-gamma might constitute a marker of this drug's effects. We measured the capacity for mitogen-stimulated production of these cytokines in whole blood by using immunostaining of intracellular and membrane antigens, followed by flow cytometry. The percentage of CD4+ T cells producing IL-2 or IFN-gamma was strongly reduced in 20 transplant patients compared with 24 healthy controls. The capacity for IL-2 production of CD4+ and CD8+ cells correlated inversely with CSA blood levels (P values 0.0087 and 0.0396, respectively). IFN-gamma production by CD4+ T cells showed a negative correlation with the prednisolone dose (P = 0.0175) and, for the CD8+ subset, with CSA trough levels (P = 0.0023). These data show that inhibition of T cell cytokine synthesis by CSA and prednisolone can be quantified.

Flow Cytometry↗
PubMed1998

A sensitive method for quantifying cytomegalic endothelial cells in peripheral blood from cytomegalovirus-infected patients.

A sensitive method has been developed for the quantification of cytomegalic endothelial cells (CEC) in peripheral blood (PB) of patients with active cytomegalovirus (CMV) infections. The three subsequent key steps of this method are density centrifugation to enrich endothelial cells (EC) in the mononuclear cell (MNC) fraction, EC-specific staining, and fluorescence-activated cell sorting (FACS) of EC onto adhesion slides. The FACS method was compared with the conventional method of cytocentrifugation of the MNC fraction onto slides, followed by EC-specific staining. The main advantage of the additional steps for the isolation and quantification of CEC in PB by FACS is a 10-times-greater sensitivity than by cytocentrifugation of the MNC fraction alone. The recovery percentages of EC from whole blood were comparable for both methods. Recoveries of EC obtained after FACS were 53% +/- 16.5%, (mean +/- standard deviation), and recoveries of EC obtained after cytocentrifugation of the MNC fraction were 43% +/- 4.3%. In patients with active CMV infection, 5 to 72 CEC were detected by FACS, equivalent to 0.8 to 9.0 CEC/ml of blood. With this method for isolation and quantification, the characterization of CEC in PB of patients with CMV-associated clinical symptoms, as well as the quantification of EC in PB of patients with pathophysiological manifestations involving endothelial damage that are different from those caused by CMV infections, can be performed.

Animals↗
PubMed1998

Studies on the induction of antigen-specific antibody in anti-CD40 cultured human B lymphocytes.

Costimulatory signals provided by T cells are required for B cells to produce specific antibody to T-dependent antigen. We have investigated the suitability of using the CD40 culture system for the proliferation and differentiation of Ag-specific human B cells using cytomegalovirus (CMV) or tetanus toxoid (TT) as antigen. We modified the CD40 culture system (CD32-transfected L cells, anti-CD40, and IL-4) by applying a sequential cytokine stimulation and compared total B-cell cultures with antigen-specific B cells preselected by panning. The detection of specific antibody became possible when antigen-selected B cells were cultured for 7 days in the CD40 system to induce clonal expansion, followed by the addition of IL-2 and IL-10 for an additional 7 days to induce plasma-cell differentiation. We conclude that our initial inability to detect specific antibody in the CD40 system is due to overgrowth of nonspecific B-cell clones and that selection of antigen-specific B cells by panning overcomes this problem. Induction of antigen-specific antibody production was found to be optimal when the initial contact with antigen during panning was limited to between 1 to 24 hours.

Antibodies, Bacterial↗
PubMed1998

Prior cytomegalovirus infection does not predict clinical outcome after percutaneous transluminal coronary angioplasty.

BACKGROUND: A direct association between human cytomegalovirus (HCMV) infection and the development of restenosis after coronary angioplasty has been suggested. The aim of this prospective study was to evaluate the value of HCMV serology in predicting the clinical outcome after percutaneous transluminal coronary angioplasty (PTCA). METHODS AND RESULTS: 112 patients undergoing elective PTCA were included in the study. HCMV antibody levels were measured by ELISA. Cardiac events within a follow-up period of 6 months after PTCA were defined as (1) progression or recurrence of anginal complaints and/or a positive exercise test; (2) restenosis that required repeat revascularization. 73% of PTCA patients were seropositive for HCMV. Successful PTCA was achieved in a total of 94 patients, who were followed for 6 months. In 31/94 patients (33%) cardiac events occurred and in 15/94 (16%), this could be related to restenosis. We found no statistically significant difference between seropositive and negative patients with respect to anginal complaints or the need for revascularization. There was no evidence of acute reactivation, since titers of anti-HCMV antibodies did not increase after PTCA. CONCLUSION: This study shows that the clinical outcome after PTCA is not related to the HCMV serostatus of the patient. Therefore, our data do not support the hypothesis that serological markers of HCMV infection are of clinical importance for the assessment of a patient's individual risk after PTCA. This does not preclude a role for local reactivation of HCMV at the site of angioplasty.

Acute Disease↗