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Biomedical subjects

T H The

Publications and source records attributed to T H The.

At least 19 recordsLinked to original sources
PubMed1992

Direct visualisation and quantification of cellular cytotoxicity using two colour flourescence.

A fluorescence method is described for the evaluation of cell death induced by cellular cytolytic activity. A green fluorescent membrane dye, D275, was used to label various target cell lines and propidium iodide (PI) uptake was used to assay cell death. Natural killer (NK), lymphokine activated killer (LAK) as well as targeted T cell mediated cellular cytotoxicity were quantified using the fluorescence method and compared to results obtained with the 51chromium (51Cr) release assay. A good correlation was found after an assay period of 4-8 h indicating that the fluorescence method is a reliable alternative to the 51Cr release assay.

Carbocyanines↗
PubMed1992

Increased production of antigen-specific B lymphocytes during in vitro immunization using carrier-specific T helper hybridomas.

An in vitro method to increase the production of hapten-specific antibody-forming B cells (AFC) using a carrier-specific T helper hybridoma and murine splenocytes is described. Naive splenocytes (6 x 10(6)/ml) are cultured in vitro in the presence of a hapten-carrier conjugate (DNP.OVA) and OVA-specific T helper hybridomas (0.5 x 10(6)/ml). After 4-5 days in vitro immunization (IVI), the maximum number of DNP-specific AFC were found using a spot-ELISA with twice the number of IgM positive cells as IgG positive AFC. The presence of antigen in the form of a hapten-carrier complex and the use of a carrier-specific Th hybridoma resulted in more hapten-specific AFC than when neither antigen nor Th hybridoma were present or when antigen alone or T help alone were used. Also when the hapten was conjugated to a carrier not recognised by the carrier-specific Th hybridoma there were considerably fewer (less than 50%) hapten specific AFC formed. When in vivo primed splenocytes (DNP) were boosted in vitro (IVB) under the same conditions as for IVI most hapten-specific AFC were found on day 4 and both anti-DNP IgM and IgG AFC were increased relative to IVI. Again most AFC were found when hapten was bound to the relevant carrier. In conclusion, carrier-specific T hybridomas can be used in an in vitro immunization procedure with naive or primed splenocytes to increase the frequency of anti-hapten AFC. This method offers an improvement over the current in vitro immunization procedures for the production of monoclonal antibodies.

Animals↗
PubMed1992

Dextran-magnetite particles: contrast-enhanced MRI of blood-brain barrier disruption in a rat model.

Dextran-magnetite particles (DMP) were studied for their use as a MR contrast agent to visualize lesions with a blood-brain barrier (bbb) disruption. A freezing injury to the rat cerebral cortex was used as a model of bbb disruption. The biodistribution of iv-injected DMP was studied using atomic absorption spectrophotometry, electron microscopy, and MRI. One hour after injection, focal accumulation of the particles in capillary endothelial cells could be demonstrated in the freezing lesion. Despite the observation that the relaxivity of DMP in vivo appears to be less well pronounced than that in vitro, the MR imaging studies show that DMP can be used to visualize bbb disruption with adequate contrast.

Animals↗
PubMed1992

Specific MR imaging of human lymphocytes by monoclonal antibody-guided dextran-magnetite particles.

Human lymphocytes were labeled with biotinylated anti-lymphocyte-directed monoclonal antibodies, to which streptavidin and subsequently biotinylated dextran-magnetite particles were coupled. This labeling resulted in a strong and selective negative contrast enhancement of lymphocyte suspensions at 2.0 T, caused predominantly by the specific increase of R2 with a small but significant specific increase of R1. The R1 was found to decrease with increasing field strength. The immunolabeling procedure described here may be used for the selective signal depletion of target cells in MR imaging.

Antibodies, Monoclonal↗
PubMed1992

Monitoring antigenemia is useful in guiding treatment of severe cytomegalovirus disease after organ transplantation.

We investigated the value of monitoring CMV antigenemia during and after antiviral therapy for CMV disease. During the study period, 10 out of 214 renal transplant recipients were treated for CMV disease, receiving a total of 14 courses of treatment. Antigenemia decreased within 7 days after onset of treatment in eight of nine courses associated with a rapid clinical recovery. In three courses with a slow or absent response, antigenemia levels initially increased. Monitoring antigenemia was helpful in differentiating persisting CMV disease from other opportunistic infections and rejection. Relapses of CMV disease were preceded by rises in antigenemia. Viral isolation became negative within 3 days after initiation of ganciclovir, irrespective of the clinical response. Antigenemia is a marker of the effect of ganciclovir on CMV replication in vivo, and its monitoring may be valuable in the management of patients with severe CMV disease.

Adult↗
PubMed1992

Peripheral blood lymphocyte number and phenotype prior to therapy correlate with response in subcutaneously applied rIL-2 therapy of renal cell carcinoma.

The phenotype of peripheral blood lymphocytes of 27 renal cell carcinoma patients before and at the end of subcutaneously given rIL-2 therapy was determined by two colour flow cytometry. Therapy induced changes in peripheral blood leucocyte composition and phenotypes were comparable to those reported for intravenously given rIL-2. The present paper shows a correlation between the 'activation status' of the patient before therapy and eventual response.

Adult↗
PubMed1992

The lower matrix protein pp65 is the principal viral antigen present in peripheral blood leukocytes during an active cytomegalovirus infection.

During an active infection with human cytomegalovirus (HCMV), viral antigen is consistently present in peripheral blood leukocytes. Two monoclonal antibodies (MAbs), CMV-C10 and CMV-C11, are commonly used in the HCMV antigenaemia assay to detect these cells in the peripheral blood of patients suspected of having an active HCMV infection. We demonstrate that the viral antigen detected by these MAbs is the viral structural protein pp65 and not an immediate early antigen as previously reported. Furthermore, significantly fewer leukocytes were found to be positive with MAbs specific for immediate early antigens.

Antibodies, Monoclonal↗
PubMed1992

Antibodies to acetylcholine receptors in myasthenia gravis. In vitro synthesis by peripheral blood lymphocytes before and after thymectomy.

Pokeweed mitogen (PWM)-driven in vitro synthesis of antibodies to the acetylcholine receptor (PSA) was studied in non-thymoma patients with myasthenia gravis. In a group of 46 patients, the occurrence of PSA was related to the presence of the thymus or, in operated patients, the absence of a clinical effect of thymectomy. Sixteen patients were followed before and soon after thymectomy. PSA disappeared in all patients, at least temporarily, between 6 weeks and 1 year afterwards, independent of the clinical course and eventual clinical effect of the operation. A recurrence was found only in one of the five patients who derived no benefit from the operation. These findings support the hypothesis that the therapeutic effect of thymectomy can be explained by removal of a source of autoreactive lymphocytes. There was no correlation between the changes in serum levels of a-AChR and clinical improvement, suggesting a minor role of circulating peripheral blood lymphocytes (PBL) and the thymus in the total production of a-AChR.

Adult↗
PubMed1991

Detection of autoantibodies against myeloid lysosomal enzymes: a useful adjunct to classification of patients with biopsy-proven necrotizing arteritis.

PURPOSE: Assessment of the value of determination of antineutrophil cytoplasmic antibodies (ANCA) and its specificities for classification of patients with biopsy-proven necrotizing arteritis. PATIENTS AND METHODS: The serum samples of 28 consecutive patients with biopsy-proven vasculitis involving medium- and/or small-sized arteries were tested for ANCA by an indirect immunofluorescence technique, by neutrophil extract enzyme-linked immunosorbent assay (ELISA), and by catching ELISA. RESULTS: Eight patients had Churg-Strauss syndrome; six had myeloperoxidase (MPO) antibodies, and in the other two patients, ANCA were not detected. Six patients had polyarteritis nodosa (PAN) limited to the skin and the musculoskeletal system; ANCA were not detected in these patients. Two patients had systemic PAN and both had MPO antibodies. The remaining 12 patients had overlapping clinical features of the different forms of vasculitis. Five patients had polyarteritis in combination with chronic nasal inflammation and glomerulonephritis compatible with Wegener's granulomatosis (WG) but without granulomas in the respiratory tract. All five patients had 29-kd serine protease antibodies. Two patients had polyarteritis in combination with nasal polyposis and asthma compatible with Churg-Strauss syndrome, but eosinophilia was not detected. Both patients had MPO antibodies. Three patients with unclassified granulomatous arteritis had either elastase antibodies or ANCA of unknown specificity. One patient with unclassified systemic vasculitis had 29-kd serine protease antibodies, and one patient with necrotizing arteritis of the bowel in combination with Schönlein-Henoch purpura was negative for ANCA. CONCLUSION: Determination of ANCA and its specificities is a useful adjunct to the classification of patients with biopsy-proven necrotizing arteritis. Within the spectrum of idiopathic vasculitides, 29-kd serine protease antibodies are associated with WG, MPO antibodies are associated with Churg-Strauss syndrome and systemic PAN, and PAN limited to the skin and the musculoskeletal system is not associated with ANCA.

Adult↗
PubMed1991

Anti-acetylcholine receptor antibodies decrease after thymectomy in patients with myasthenia gravis. Clinical correlations.

Clinical course and changes in serum levels of antibodies to the acetylcholine receptor (a-AChR) were followed in 82 patients with myasthenia gravis during a period of 1-8 years after thymectomy. Decrease in a-AChR immediately after thymectomy was influenced by changes in a total IgG. Immunosuppressive medication affected serum a-AChR at all points of time. In a subgroup of 41 patients without thymoma who had no immunosuppressive drugs, there was a steady decrease in a-AChR concomitant with clinical improvement from 6 weeks after thymectomy.

Adolescent↗
PubMed1991

Antigenemia in the diagnosis and monitoring of active cytomegalovirus infection after liver transplantation.

In 45 liver transplant recipients, the value of weekly monitoring of cytomegalovirus (CMV) antigenemia for early diagnosis of active CMV infection was compared with serology and rapid viral isolation. Active CMV infection occurred in 23 patients. The sensitivities of the antigenemia assay and serology (of blood) and rapid viral isolation (from blood or urine) were 96%, 96%, 57%, and 70%, respectively. First diagnostic results of these methods were obtained a median of 25, 36, 31, and 49 days, respectively, after transplant. CMV infection was symptomatic in 20 patients; antigenemia was present at the onset of disease in 13 of these. Maximum CMV antigenemia levels were higher in patients with severe disease than in those with mild or asymptomatic infection. CMV antigenemia is a sensitive, early, quantitative marker of active CMV infection after liver transplantation.

Adult↗
PubMed1991

Cytomegalovirus-specific antibodies to an immediate early antigen and a late membrane antigen and their possible role in controlling secondary cytomegalovirus infection.

In 24 renal transplant recipients who had a secondary cytomegalovirus (CMV) infection, the magnitude and development of CMV-specific antibodies directed against two different antigens were studied in relation to the presence of CMV-immediate early antigen-positive peripheral blood leucocytes (CMV antigenaemia). These antibodies were measured in an antigen-capture ELISA using two monoclonal antibodies: one directed against the major immediate early antigen (IEA) and a second one directed against the CMV-encoded glycoprotein B (gB). A statistically significant inverse relationship between the level of anti-IEA antibodies present at the time of transplantation as well as the magnitude of the increase of these antibodies during CMV infection and the maximum number of IEA-positive cells during infection was shown. In contrast, both anti-gB and anti-total CMV antibodies did not give any correlation with the CMV antigenaemia. This may indicate that the anti-IEA immune response plays a role in defence mechanisms against a CMV infection.

Antibodies, Monoclonal↗