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K Wonigeit

Publications and source records attributed to K Wonigeit.

At least 73 records · Page 4Linked to original sources
PubMed1994

Human CD45RA+ and CD45R0+ T cells exhibit similar CD3/T cell receptor-mediated transmembrane signaling capacities but differ in response to co-stimulatory signals.

CD45RA+ cells have been described to be less responsive to CD3/T cell receptor (TcR)-mediated activation than CD45R0+ T cells. To analyze the underlying mechanism of the differential responses we compared CD3/TcR-triggered tyrosine phosphorylation in the two subsets and studied the role of co-stimulatory signals provided either by accessory cells or pharmacologic activation of protein kinase C by phorbol ester. Stimulation of purified CD45RA+ and CD45R0+ T cells with CD3/TcR antibodies induced similar patterns and intensities of tyrosine phosphorylation in the two subsets, but no proliferation. If accessory cells were used as the source of co-stimulatory signals, strong expression of the 55-kDa chain of the interleukin-2 (IL-2) receptor (CD25), significant IL-2 production and vigorous proliferation were observed in CD45R0+ cells, whereas CD45RA+ cells responded weakly. However, when CD3/TcR-mediated triggering was combined with activation of protein kinase C by phorbol ester, CD45RA+ cells responded strongly. These data indicate that the transmembrane signaling capacity of the T cell receptor expressed by CD45RA+ and CD45R0+ cells is similar and, therefore, is presumably not responsible for the differential reactivities of the two subsets. It is more likely that co-stimulatory signals determine whether CD3/TcR-initiated activation results in strong or weak responses.

Antigen-Presenting Cells↗
PubMed1994

The use of plasma levels for FK 506 dosing in liver-grafted patients.

FK 506 plasma levels were analyzed in 89 liver-grafted patients under FK 506-based immunosuppression. Plasma levels were found to be influenced by the patients' liver function: compared to patients without major liver dysfunction, those with cholestasis had higher plasma levels and these plasma levels were able to differentiate between rejection and toxicity. In patients with stable liver function, no clear difference was observed with regard to the plasma levels detectable during toxicity or rejection. We conclude that plasma levels can be used to determine the FK 506 dose but only in patients with cholestasis (i.e., during the early post-transplant course, or in patients with cholestatic rejection). In patients with stable liver function, plasma levels are only of limited clinical relevance.

Cholestasis↗
PubMed1994

Preferential TCR V usage in rat repertoire selection: V alpha 8 imparts both positive thymic selection by and alloreactivity to RT1f.

Using a panel of newly developed mAb to two rat TCR V alpha and four TCR V beta segments, TCR V usage in CD4 and CD8 T cells of eight RT1 congenic strains sharing the LEW background was analyzed by flow cytometry. While no striking effects on V beta 8.2 and 8.5 usage were observed, a 3- to 4-fold over-representation of V beta 10 in the CD4 as compared with the CD8 subset in all strains suggested a preference of V beta 10 for MHC class II products. The degree of 'overselection' was mapped to the RT1.B/D region. In addition, an allele-specific overselection of V alpha 4+ CD4 T cells was mapped to RT1.B/Du and of V beta 16+ CD8 T cells to RT1.Au. Finally, a dramatic overselection of V alpha 8+ CD8 T cells by RT1f (14% in RT1f versus 1-2% in other haplotypes) provides the most striking case yet for an intrinsic affinity of a TCR V segment for an MHC product. V alpha 8+ CD8 T cells are not only overselected by RT1f in the thymus, but also during the alloreactive response of peripheral CD8 T cells to RT1f. The implications of these findings for the contribution of TCR V segments to TCR-MHC interactions in repertoire selection and alloreactivity are discussed.

Animals↗
PubMed1994

Plasma vs whole blood for therapeutic drug monitoring of patients receiving FK 506 for immunosuppression.

By retrospective analysis of 13,000 blood samples obtained from 248 patients receiving FK 506 therapy, we compared the suitability of plasma with that of whole blood as the matrix for therapeutic drug monitoring of FK 506. The plasma concentrations did not correlate with the concentrations in whole blood (r = 0.56). In contrast to plasma samples (analyzed by enzyme immunoassay), FK 506 was detectable in all whole-blood samples (analyzed by enzyme immunoassay/microparticle enzyme immunoassay). The inter- and intraindividual variations of FK 506 measurements were greater in plasma than in whole blood. Moreover, plasma concentrations correlated only poorly with clinical events. There was a tendency to greater plasma concentrations being measured during episodes of toxicity, but no clear difference was evident between stable course and rejection. In whole-blood specimens, a correlation between reduced or increased FK 506 concentrations and rejection or toxicity, respectively, was observed. The discriminatory power of whole-blood values was greater for the differentiation between toxicity and stable course than between rejection and stable course. We therefore recommend whole blood rather than plasma as the matrix for therapeutic monitoring of FK 506 concentrations.

Drug Monitoring↗
PubMed1993

Peptide translocation by variants of the transporter associated with antigen processing.

Major histocompatibility complex (MHC) class I molecules associate with peptides that are delivered from the cytosol to the lumen of the endoplasmic reticulum by the transporter associated with antigen processing (TAP). Liver microsomes of SHR and Lewis rats, which express different alleles of TAP (cim(b) and cim(a), respectively), accumulate different sets of peptides. Use of MHC congenic rats assigned this difference to the MHC, independent of the class I products expressed. Both the cim(a) and cim(b) TAP complexes translocate peptides with a hydrophobic carboxyl terminus, but translocation of peptides with a carboxyl-terminal His, Lys, or Arg residue is unique to cim(a). Thus, the specificity of the TAP peptide translocator restricts the peptides available for antigen presentation.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1993

Serum bile acids and esterified bilirubin in early detection and differential diagnosis of hepatic dysfunction following orthotopic liver transplantation.

Routine laboratory tests are of little help for early detection and differential diagnosis of hepatic dysfunction following orthotopic liver transplantation (OLT). In the present study, serum levels of esterified bilirubin, total bilirubin and bile acids were investigated in 20 patients after OLT. Twenty episodes of liver dysfunction were observed: 10 rejection episodes, 3 cases of thrombosis of the hepatic artery, 3 cases of septic shock, and 4 episodes of cyclosporin toxicity. During rejection, the median increase in esterified bilirubin was 3.2-fold (range 1.6-24.9), while total bilirubin increased 1.5-fold (range 0.7-3.4). Bile acids increased 3.6-fold (range 2.5-6.6; peak levels 25-87 microM). Both bile acids and esterified bilirubin increased 1-3 days earlier than serum transaminases and decreased only after successful anti-rejection treatment. The response of bile acids to successful treatment was usually more rapid than the response of esterified bilirubin. Hepatic artery thrombosis and septic shock were associated with a sharp increase in esterified bilirubin and very high bile acid levels (peak levels 80-185 microM). During cyclosporin toxicity, a characteristic pattern of progressively increasing bilirubin with no change in the bile acid levels was observed. Both esterified bilirubin and bile acids are very sensitive indicators of hepatic graft dysfunction. In particular, serum bile acids are useful for identifying cyclosporin toxicity and monitoring the response to anti-rejection treatment.

Bile Acids and Salts↗
PubMed1993

Production of cytokines (TNF-alpha, IL-1-beta) and endothelial cell activation in human liver allograft rejection.

Intragraft production of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1-beta (IL-1-beta) was determined in rejecting human liver grafts during acute rejection and in chronic graft dysfunction. The localization of cytokine-producing cells was then correlated with the distribution of monocytes and macrophages as their main producers, as well as with effector functions such as endothelial cell activation. In selected patients collateral TNF-alpha plasma levels were measured. In normal liver and biopsies taken during an uncomplicated course, few TNF-alpha and even fewer IL-1-beta positive macrophages were found. During acute rejection episodes of all degrees of severity liver grafts were infiltrated by large numbers of TNF-alpha-positive monocytes, and concomitant TNF-alpha plasma levels were elevated compared with uncomplicated controls. In marked contrast IL-1-beta production by macrophages and vascular and sinus endothelial cells was restricted to the most severe, irreversible rejection episodes. The localization of cytokine-positive cells coincided with areas of maximum induction of ICAM-1 and von Willebrand Factor. In chronic graft dysfunction increased numbers of mature macrophages were found. A large proportion of these were positive for TNF-alpha as well as IL-1-beta. Distinct from acute rejection episodes, however, parallel TNF-alpha plasma levels were not elevated, suggesting cytokine storage rather than secretion. The present results indicate an important local role of TNF-alpha and IL-1-beta in the early phase of the rejection process. They presumably activate endothelial cells to upregulate the expression of adhesion molecules, thereby facilitating mononuclear cell adhesion and extravasation. Therefore, specific inactivation of cytokines or of their actions may prove to be a powerful tool in the prevention and treatment of allograft rejection in the future.

Cell Adhesion Molecules↗
PubMed1993

Passenger lymphocytes in human liver allografts and their potential role after transplantation.

Rare cases of graft-versus-host disease after liver transplantation indicate that donor lymphocytes may be transferred to the recipient by human liver grafts. In this study, we have analyzed the number and subpopulations of donor lymphocytes transferred by liver grafts in order to evaluate the potential relevance of these cells after transplantation. Therefore, mononuclear cells were isolated from the tissue of perfused human donor livers and from the associated lymph nodes. The number of lymphocytes, their location, and surface marker expression were determined by immunostaining. The majority of lymphocytes transferred by the grafts were found within the liver tissue (5.3 +/- 2.9 x 10(9) cells). These lymphocytes are mainly T and NK cells, predominantly CD8+, are partially activated (28% HLA-DR+), and show strong adhesion molecule expression (88% LFA-1(3+)). In addition, 20-500 x 10(6) of resting lymphocytes, predominantly T and B cells, are transmitted by lymph nodes. These findings demonstrate that considerable numbers of donor lymphocytes of distinct phenotype are regularly transmitted to the recipient by human liver grafts and may be of functional relevance after transplantation.

Antigens, CD↗
PubMed1993

Persistence of donor lymphocytes in liver allograft recipients.

Occasional cases of graft-versus-host disease after liver transplantation indicate a transfer of donor lymphocytes by human liver grafts. However, little is known about the usual fate and potential function of passenger lymphocytes in clinical liver transplantation. In this study, we have analyzed liver graft recipients for the presence of donor lymphocytes in the early course after transplantation. The presence of such cells in blood, the graft, and, occasionally, the skin was studied by the use of mAb to polymorphic HLA class I determinants and double-staining techniques in flow cytometry and immunocytology. The findings were compared with the clinical courses and with the results of routine graft biopsies. Within the first week after transplantation, in all 16 patients, between 1% and 24% donor lymphocytes (T, NK, and B cells) were detectable in blood, and in 14 of 22 patients (64%), between 2% and 23% donor T cells were found in the graft. After more than 2 weeks, donor cells were still present in blood in 2 of 14 patients at very low numbers. The presence of donor lymphocytes in the graft was associated with intragraft immune activation in 5 of 15 patients, but no clinical rejection occurred in these cases; mild graft-versus-host disease was observed in one patient. These findings demonstrate that donor lymphocytes regularly persist in liver-grafted patients for some time; this transient mixed lymphoid chimerism is only rarely associated with clinical graft-versus-host disease and some evidence even suggests that these donor-derived lymphocytes may exert beneficial immunomodulatory properties.

Adult↗
PubMed1993

Responsiveness for mouse IgG2b antibodies to the human alpha/beta T-cell receptor/CD3 complex: evidence for genetic determination and low grade antibody cross-linking not mediated by known Fc gamma receptors.

Mouse IgG2a and IgG3 antibodies directed to the human T-cell receptor/CD3 complex stimulate peripheral blood mononuclear cells in almost all individuals. By contrast, responder and non-responder individuals exist for the stimulatory effect of mouse IgG1 and IgG2b antibodies. Whereas responsiveness to IgG1 antibodies is rather frequent (60-70%) and is known to be determined by an Fc gamma RII polymorphism on the accessory cells, little is known about the underlying factors of the rare (6%) IgG2b responsiveness. In this study it is shown that (1) IgG2b responsiveness is genetically determined with a dominant pattern of inheritance; (2) IgG2b responsiveness is determined by a radioresistant feature of responder accessory cells which can be substituted by artificial cross-linking, but not by IL-1 beta or IL-2; (3) stimulation of peripheral blood mononuclear cells of an IgG2b responder by IgG2b antibodies requires rather high antibody concentration compared with stimulation by IgG2a antibodies; (4) the stimulation leads to proliferation and IL-2 receptor expression, but no measurable IL-2 production; (5) antibody binding to known Fc gamma receptors (Fc gamma RI, Fc gamma RII, Fc gamma RIII) is not involved in the stimulatory effect of the IgG2b antibodies in responders. These results demonstrate that responsiveness to IgG2b antibodies against the TcR/CD3 complex depends on a genetically determined feature of accessory cells that is not identical with any of the known Fc gamma receptors. Most likely, the stimulatory effect observed in IgG2b responders is explained by a low grade cross-linking of the antibody by a not yet identified polymorphic structure on the surface of accessory cells.

Animals↗
PubMed1993

Monitoring cyclosporin A (ciclosporin, INN) concentrations in whole blood: evaluation of the EMIT assay in comparison with HPLC and RIA.

We report here on an evaluation of the enzyme-multiplied immunoassay technique (EMIT) from Syva for cyclosporin A (ciclosporin, INN) concentration measurements in whole blood. The assay incorporates a monoclonal antibody for specific determination of ciclosporin. Measurements by EMIT were performed on the Cobas Mira-S from Roche. A total of 197 blood specimens from heart-(n = 74), kidney-(n = 62) and liver-(n = 61) transplant recipients were analyzed. EMIT values correlated well with those obtained by HPLC, as well as with those obtained by a selective radioimmunoassay (INCStar). Ciclosporin concentrations determined by EMIT (y) agreed very well with those by RIA, and averaged 8% higher than those by HPLC (x) [n = 197, mean = 143 micrograms/l, y = 155 micrograms/l, y = 1.09x - 0.6, r = 0.969]. Within-series and between-days CVs ranged from 4.6% to 7.3% for ciclosporin concentrations > 100 micrograms/l, and from 5.5% to 10.5% for ciclosporin concentrations between 69.5 micrograms/l and 100 micrograms/l. The within-series CV for a concentration of 45.5 micrograms/l was 14.8%. Calibration employing a 2-point mode instead of a continuous mode of UV-signal evaluation improved the precision of the EMIT assay at low ciclosporin concentrations. Sample pretreatment required thorough and skillful performance to avoid false positive ciclosporin measurements. We conclude that the EMIT assay is specific, and rapid to perform. It can be effectively used in the monitoring of ciclosporin concentrations in whole blood.

Antibodies, Monoclonal↗
PubMed1993

The Mycoplasma arthritidis infection in congenitally athymic nude rats.

Fifteen young (47-81 days old) and 5 adult (360 days old) Rowett nude rats (rnu/rnu) and 12 euthymic littermates (rnu/+) (56 days old) were infected with Mycoplasma (M.) arthritidis ISR1. The polyarthritis developing after the infection was more severe in the athymic than in the euthymic rats. In the nude rats the disease was progressive and led to the death of 6 animals whereas in the euthymic littermates the disease was resolved within 70 days after infection. In contrast to euthymic rats athymic animals did not develop antibodies against M. arthritidis within 6 weeks (young nude rats) or 23 weeks (adult nude rats) after infection, indicating that M. arthritidis is a thymus dependent antigen. However, low antibody titers were found in the nude rats infected at an age between 47 and 81 days at 340 days after infection, probably due to the development of T-cells which occur in older nude rats. The euthymic as well as the young athymic rats showed an increase in antibody titers after a challenge infection 345 days after the first infection and both were resistant to challenge infection. On the contrary the adult nude rats infected with M. arthritidis did not develop antibodies against the mycoplasmas and were highly susceptible to a second infection after 198 days. This indicates that antibodies play an important role in the defence of the M. arthritidis infection in rats.

Aging↗