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Biomedical subjects

B K Shenton

Publications and source records attributed to B K Shenton.

At least 91 records · Page 5Linked to original sources
PubMed1991

Renal allograft rejection. Functional impairment of kidney epithelial cell monolayers mediated by lymphokine-activated killer cells and by antibody.

A continuous line of human kidney epithelial cells was cultured to confluency on porous membranes, and the formation of intercellular tight junctions was monitored by measuring increases in the trans-monolayer electrical resistance. Typical monolayers developed functioning tight junctions within 4 days of culture and showed an increase in resistance of 1840 +/- 440 ohms (mean +/- SD; n = 5) at this time. Conventional 51Cr release assays showed that suspended kidney cells were lysed by specific antibody and complement but were relatively resistant to lysis mediated by lymphokine-activated killer cells. However, when antibody and complement or LAK cells were added to functioning kidney cell monolayers the electrical resistance of the monolayers was rapidly reduced in both cases. In the absence of trans-monolayer resistance the ion gradients essential for renal tubular function will not be supported. These results indicate that the ability of a cytotoxic effector cell to liberate 51Cr from suspended kidney cells may not be a sensitive assay for the ability of these effector cells to impair the function of structured kidney cell monolayers. It is possible that significant kidney dysfunction may occur during renal allograft rejection by failure of trans-epithelium resistance in the absence of widespread epithelial cell lysis.

Animals↗
PubMed1991

Alterations in circulating lymphocyte number and function after circulation through colorectal carcinomas.

Thirty-six patients undergoing curative resection for colorectal cancer were studied to determine the effect of the tumor on lymphocytes circulating through it. In the venous blood draining the tumor, there was an increased percentage of natural killer (NK) cells (p = 0.001), no difference in overall NK cell function, and decreased T-lymphocyte activation (p = 0.035) and proliferation (p = 0.002) compared with the lymphocytes in the arterial blood supplying the tumor. There were no significant differences in the control group of 16 patients. Local effects of colorectal cancer may include the ability to down-regulate T and NK cell function while increasing the number of NK cells. Means of enhancing antitumor activity therapeutically in an adjuvant setting, possibly through the portal vein during surgery, need to be considered, especially in the light of the immunosuppressive effects of surgery.

Aged↗
PubMed1990

Thallous chloride uptake and DNA profile in parathyroid adenomas.

Thallium isotope scintigraphy is used to localize parathyroid adenomas but the mechanism underlying the technique is poorly understood. While larger adenomas are reliably localized the results are less certain for small tumours. This study explores the relationship between cellular DNA profile and thallium uptake (localization accuracy) in 24 parathyroid adenomas. The DNA profile was assessed using flow cytometry and standard subtraction thallium scintigraphy was performed before surgery. Fifteen of the 24 adenomas demonstrated excessive mitotic activity and 13 of these glands were accurately localized. Of the remaining nine glands, only five were localized accurately (P less than 0.01, chi 2 test including Yates' correction). This difference in thallium uptake could not be accounted for on the basis of gland weight. Thallium localization of parathyroid adenomas is related to mitotic activity. This may explain some of the limitations of this technique.

Adenoma↗
PubMed1990

Monitoring of transplant patients' lymphocytes: knowledge of the varying specificities of anti-lymphocyte antibodies allows the interpretation of anomalous results.

In many transplant centers, the T lymphocytes of transplant patients are routinely monitored, both to predict and diagnose the cellular events that result from transplantation and to evaluate the effectiveness of immunosuppressive therapy. During the course of this monitoring, we have observed anomalous results: the number of T cells said to be present varies greatly depending on the surface marker used for the assay. It is shown, in this study, that these "anomalous" results can be predicted from a knowledge of the spectrum of specificity of the anti-lymphocyte antibody therapy being administered. Because polyclonal antibodies have varied and unstated specificities, it is difficult to interpret results obtained from monitoring T-cell numbers or subset ratios without some knowledge of the specificities of the drugs being used.

Antibodies↗
PubMed1990

Renal allograft rejection. Possible involvement of antibody-dependent cell-mediated cytotoxicity.

We have demonstrated that serum from appropriately sensitized patients can contain IgG antibodies that bind to cultured renal epithelial cells. The presence of such antibodies on the surface of renal cells enables otherwise nonlytic PBMC to lyse these renal cells by an antibody-dependent cell-mediated cytotoxicity (ADCC) mechanism. Experiments involving cell-sorting and specific complement-mediated lysis showed that the ADCC effector cells were of the CD3 -ve, C16 +ve phenotype characteristic of NK cells. In this report it is argued that an ADCC mechanism may be of importance in mediating chronic renal cell damage in the absence of acute allograft rejection.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1990

Blood transfusion and surgery: the effect on growth of a syngeneic sarcoma.

The effects of blood transfusion, blood components, and surgical trauma on the growth of an experimental sarcoma have been examined. Recipient animals were inbred adult female WAB rats, which received allogeneic transfusions from inbred adult female PVG rats, syngeneic blood from inbred colony-mates, or saline infusions. Small volume transfusions (1-4 ml) of whole blood had no effect on tumour growth, but growth of the MC7 sarcoma was significantly enhanced following allogeneic transfusions of 5 ml whole blood, or when 4 ml was combined with sham laparotomy. Maximal enhancement of tumour growth occurred when 4 ml transfusions of allogeneic washed cells were given, but allogeneic plasma was also able, to a lesser degree, to enhance tumour growth. These data confirm that blood transfusion may enhance growth of the MC7 sarcoma, that the effect may be dose dependent, and synergistic with the immunosuppression of surgery. Many components of an allogeneic transfusion may be responsible for this effect.

Animals↗
PubMed1989

A flow cytometric technique for simultaneous analysis of human mononuclear cell surface antigens and DNA.

A method for dual staining of mononuclear cells for lymphocyte phenotypic markers and DNA is described. The cells were stained with fluorescein-conjugated monoclonal antibodies and then rendered permeable to propidium iodide using saponin. Propidium iodide stains DNA and, using flow cytometry, cell cycle analysis of individual lymphocyte subpopulations can be determined. Saponin acts within 1 min, preserves expression of surface antigens and is effective at all concentrations from 0.001% to 1%. This technique is simple, rapid and gives reproducible results.

Antigens, Surface↗
PubMed1989

A phase I study of immunostimulation and toxicity in patients with colorectal carcinoma using the immunomodulator 3,6-bis(2-piperidinoethoxy) acridine trihydrochloride (CL 246738).

Seventeen patients with residual or recurrent colorectal carcinoma were given a new synthetic immunomodulator [3,6-bis(2-piperidinoethoxy) acridine trihydrochloride CL246738) as part of a phase I clinical trial. No patients had undergone previous immunotherapy or chemotherapy. Detailed immunological studies including interferon levels, interleukin 2 levels, natural killer cell function, mitogen responses of lymphocytes, immunoglobulin levels and lymphocyte subpopulation levels were analysed in the patients who received this drug in an attempt to find out whether there was any biological activity identifiable in humans. None of the subjects showed any significant increases in post treatment values of the immunological parameters studied. Toxic effects of the drug at high doses included nausea, diarrhoea and decreased levels of consciousness. In conclusion, no immunological effects were identified following the administration of CL 246738 in human subjects with recurrent or residual colorectal cancer.

Acridines↗
PubMed1989

The relevance of a more sensitive crossmatch assay to renal transplantation.

While the importance of the standard preoperative crossmatch in predicting renal graft success is accepted, a more rapid and sensitive assay may be of additional clinical benefit. We have developed a flow cytometric assay to detect the presence of antibodies (IgG) in the recipient sera directed against donor lymphocytes, prior to transplantation. This assay is more rapid and sensitive than the conventional cytotoxic test. In a clinical study the sera of 75 renal graft recipients were tested, all of which were negative in their conventional crossmatch; 12 of these were identified as having T cell-directed IgG, and 4 had B cell antibody. Graft failure was not significantly different in the positive and negative antibody groups, as defined by flow cytometry (P = 0.147, chi square test). The incidence of postoperative complications was studied in the 60 grafts functioning at three months. Recipients with donor B or T cell directed antibodies had a longer primary nonfunction (P = 0.0098, Mann-Whitney U test), and showed a higher number of rejection episodes (P = 0.014, Mann-Whitney U test); accordingly they were more likely to require strong immunosuppressive agents such as OKT3 or ATG (P less than 0.05, chi square test). Patients with donor-directed antibodies were also hospitalised for a longer period (P = 0.015, Mann-Whitney U test) and had a higher creatinine level 3 months after transplantation (P = 0.021 Mann-Whitney U test). This study shows that the described preoperative flow cytometric crossmatch is capable of defining a population of renal transplants who form an at-risk group. Thus this assay has considerable potential in pretransplant matching of recipients with a particular graft donor.

Antibodies↗
PubMed1988

Rapid detection of low levels of donor specific IgG by flow cytometry with single and dual colour fluorescence in renal transplantation.

Lymphocytotoxic immunoglobulin is routinely assayed before human renal transplantation. If IgG directed against donor T cells is detected in the serum of the potential recipient, transplantation is not performed as it is associated with a poor graft outcome. Poor sensitivity of the conventional assay has been postulated as being the cause of some graft failures. Two new flow cytometric assays are described which are more sensitive than the conventional test. The first assay requires manual separation of T and B lymphocytes and therefore takes a similar time to perform as the conventional assay. The second assay utilises a two-colour system and lymphocyte's separation is by fluorescence. This assay takes half the time to perform, thereby decreasing graft ischaemic time before transplantation.

Dose-Response Relationship, Immunologic↗
PubMed1988

A correction required for calculation of DNA ratios in flow cytometric analysis of ploidy.

Flow cytometric measurements of nuclear DNA content often involve the calculation of a DNA index, which compares the DNA fluorescence from two different populations. Such DNA indices have been used to classify aneuploid peaks from tumour tissue into different categories relative to normal diploid cells. This report describes a correction based on the channel for unstained particles that is required if DNA index values are to give a true and reproducible indication of relative DNA content.

Animals↗
PubMed1987

A rapid, objective method for the detection of lymphocytotoxic antibodies using flow cytometry.

Whilst several centres have reported lymphocytotoxic antibody detection using single and dual fluorescent stains with analysis of the fluorescence emitted from the cell population present in a well of a multiwell plate, problems are encountered with cell concentration and light emission overlap. A method we have developed using flow cytometry produces similar values of percentage cell death using single or double staining techniques (correlation coefficient = 0.9896). This method is not influenced by slight variation in cell number or light emission overlap. The effect of introducing red cell impurities into the normal lymphocyte preparation is described.

Antilymphocyte Serum↗
PubMed1987

Fat emulsion adversely affects lymphocyte reactivity.

Although nutritional repletion of malnourished individuals may improve tests of cell-mediated immunity, the effects of intravenous nutrient solutions themselves on the immune system are largely unknown. This study examined the effects of five parenteral nutrition solutions on in vitro lymphocyte reactivity and measured lymphocyte responsiveness in patients receiving parenteral nutrition. Normal human lymphocytes were incubated with dilutions of an amino acid/dextrose solution, an amino acid/dextrose/fat solution, an amino acid solution, dextrose, and a fat emulsion, and lymphocyte responsiveness to antigenic (PPD) and mitogenic (PHA) stimulation was measured using an in vitro electrophoretic test of cell-mediated immunity. Lymphocyte reactivity was measured in 15 postoperative patients allocated randomly to receive either simple electrolyte solutions or isocaloric parenteral regimes with or without a fat emulsion. In vitro lymphocyte responses were significantly depressed (P less than 0.001) by the fat emulsion at concentrations similar to those achieved in clinical practice but were unaffected by dextrose or amino acid solutions. Lymphocyte reactivity was significantly depressed in patients during infusion of the fat emulsion in comparison with controls (P less than 0.05). The results show that fat emulsion impairs lymphocyte reactivity and suggest that careful consideration should be given before using fat emulsions in patients in whom cell-mediated immunity is impaired already.

Clinical Trials as Topic↗