Allo-HLA Cross-Reactivities of Cytomegalovirus-, Influenza-, and Varicella Zoster Virus-Specific Memory T Cells Are Shared by Different Healthy Individuals.

Virus-specific T cells can recognize allogeneic HLA (allo-HLA) through TCR cross-reactivity. The allospecificity often differs by individual (private cross-reactivity) but also can be shared by multiple individuals (public cross-reactivity); however, only a few examples of the latter have been described. Because these could facilitate alloreactivity prediction in transplantation, we aimed to identify novel public cross-reactivities of human virus-specific CD8+ T cells directed against allo-HLA by assessing their reactivity in mixed-lymphocyte reactions. Further characterization was done by studying TCR usage with primer-based DNA sequencing, cytokine production with ELISAs, and cytotoxicity with 51 chromium-release assays. We identified three novel public allo-HLA cross-reactivities of human virus-specific CD8+ T cells. CMV B35/IPS CD8+ T cells cross-reacted with HLA-B51 and/or HLA-B58/B57 (23% of tetramer-positive individuals), FLU A2/GIL (influenza IMP[58-66] HLA-A*02:01/GILGFVFTL) CD8+ T cells with HLA-B38 (90% of tetramer-positive individuals), and VZV A2/ALW (varicella zoster virus IE62[593-601] HLA-A*02:01/ALWALPHAA) CD8+ T cells with HLA-B55 (two unrelated individuals). Cross-reactivity was tested against different cell types including endothelial and epithelial cells. All cross-reactive T cells expressed a memory phenotype, emphasizing the importance for transplantation. We conclude that public allo-HLA cross-reactivity of virus-specific memory T cells is not uncommon and may create novel opportunities for alloreactivity prediction and risk estimation in transplantation.

[Late complications following renal transplantation]. / Late complicaties na niertransplantatie.

The number of renal transplant recipients is increasing steadily. Physicians from all specialties are ever more likely to encounter this vulnerable group of patients. They constitute a susceptible group because of increased mortality and morbidity. Half of the renal transplants are lost due to chronic transplant failure. The primary cause of chronic transplant failure is chronic allograft nephropathy. Other causes of transplant failure are calcineurin inhibitor toxicity, recurrence of the original renal disease such as glomerulonephritis and diabetes mellitus, stenosis of the renal artery in the transplant, and urological complications. The other half of the renal transplants are lost due to the death of the recipient. The primary cause of death is cardiovascular disease due to former chronic renal, hypertension and dyslipidemia following the use of immunosuppressants. In addition malignancies, infections and bone abnormalities do occur more frequently as compared to the normal populations. Alertness is warranted following kidney transplantation by both the patients themselves as well as all the treating specialists. Careful periodical monitoring for life is required because of the risk of the abovementioned complications.

[Immunological defense to viral infections: focus on virus-specific T cells]. / Immunologische afweer tegen virale infecties: virusspecifieke T-cellen in beeld.

T cells play a central role in the control of and the protection against viral infections. The T cell population consists ofa diversity ofvirus-specific memory T cells. The characteristics of these T cells seem to depend largely on the type of virus for which they are specific. T cells directed against latent viruses, such as cytomegalovirus, are cytotoxic cells. T cells directed against viruses that after the initial infection are completely removed by the immune system, such as the influenza virus, are non-cytotoxic cells. The development of new immunological techniques, such as the detection of virus-specific cells with HLA-peptide tetrameric complexes, enables the characterization of the properties of virus-specific T cells in the blood and organs.

Application of a monoclonal antibody against a neoepitope on activated C4 in an ELISA for the quantification of complement activation via the classical pathway.

In order to study the activation of the complement system via the classical pathway we have attempted to raise antibodies specific for C4 activation products. Of 20 mouse monoclonal antibodies (mAbs) obtained, one appeared to react with an activation dependent epitope exposed on the activation products C4b, C4bi, C4c (C4b/c) as well as on iC4, but not on native C4. Using this antibody as a capture antibody and polyclonal biotinylated antibodies against C4 as detecting antibodies we developed an ELISA for the quantification of C4b/c in biological fluids. The lower limit of detection was approximately 0.025 nmol C4b/c per litre. Mean C4b/c levels in plasma samples collected from healthy volunteers in tubes containing 10 mM EDTA and 0.05% (w/v) polybrene, final concentrations, appeared to be 30 nmol/l. The potential of the ELISA procedure for evaluating complement activation in clinical samples was demonstrated.

Comparison of T cell responses in patients with a long-term surviving renal allograft versus a long-term surviving liver allograft. It's a different world.

The aim of the present study was to analyze whether acquired transplantation tolerance had developed in patients with a long-term surviving renal or liver allograft. Analysis of antidonor cytotoxic T cell precursor frequencies was performed in 31 renal allograft recipients and 9 liver allograft recipients with good graft function 2 years after transplantation. The results demonstrated that, before transplantation, normal antidonor T cell responses were generated in both groups of patients. Two years after transplantation, donor-specific CTL nonresponsiveness had developed in a minority of the renal transplant recipients. In contrast, 8 out of 9 liver transplant recipients showed donor-specific mixed lymphocyte culture and CTL nonresponsiveness. These findings indicate that development of donor-specific T cell nonresponsiveness is not a common event after kidney transplantation, whereas liver transplantation seems to induce, at least in vitro, a state of donor-specific T cell nonresponsiveness.

Labeling with indium-111 has detrimental effects on human lymphocytes: concise communication.

When lymphocytes from human peripheral blood were labeled with In-111 oxinate, several of their properties appeared to be affected. The spontaneous release of the radionuclide was found to be relatively high. Labeled lymphocytes showed a decreased proliferative capacity, dependent on the dose of the label. Cytogenetic studies revealed that In-111 oxinate induces severe chromosomal aberrations. These results emphasize the need for great caution in the use of the In-111 label for studies on lymphocyte traffic in humans.

Sequestration of labelled granulocytes in the lungs following administration of OKT3 is dose-dependent.

In the present study the consequences of administration of low-dose (0.5 mg) OKT3 for respiratory side-effects and pulmonary sequestration of labelled granulocytes are compared with the known effects of 5 mg OKT3. Ten renal transplant patients were studied, of whom five were treated with 0.5 mg OKT3 and five with 5 mg OKT3. None of the patients in the 0.5 mg group and two of the patients in the 5 mg group experienced dyspnoea. Sequestration of labelled granulocytes in the lungs was significantly lower in the patients receiving 0.5 mg OKT3 compared with the patients receiving 5 mg OKT3. The simultaneously occurring peripheral blood granulocytopenia was significantly more severe in the 5 mg group than in the 0.5 mg group. We suppose that this sequestration of circulating granulocytes in the lungs is at least partly mediated by complement activation products. In vitro it is demonstrated that fixation of complement activation products on peripheral blood lymphocytes depends on the concentration of OKT3 present in the culture medium. We conclude that respiratory side-effects shortly following infusion of OKT3 are related to complement-induced pulmonary leucostasis, the degree of which is dependent on the administered dose of OKT3.

Increased dermal expression of ICAM-1 and VCAM-1 after administration of OKT3 in man.

OKT3 induces a systemic release of cytokines and a profound peripheral lymphocytopenia. In vitro, tumor necrosis factor-alpha, interleukin-1, and interferon-gamma increase adhesion molecule expression on vascular endothelium. To investigate the effects of OKT3 induced cytokine release on endothelial- and lymphocyte adhesion molecule expression in vivo, we studied sequential skin biopsies of six renal allograft recipients treated for acute rejection with 5 mg OKT3. An additional group of six patients treated for acute rejection with 50 mg methylprednisolone served as a control group. Compared to pre-treatment biopsies, biopsies taken 4.5- and 24 hours after the first OKT3 dose showed a maximal increase in VCAM-1 and ICAM-1 expression, respectively. In parallel, an increased number of CD2+, CD11a+, and CD49d+ mononuclear cells in the skin was observed in all OKT3 treated patients. No changes were observed after methylprednisolone treatment. We conclude that the OKT3 induced cytokine release induces increased ICAM-1- and VCAM-1 expression on vascular endothelium, leading to increased influx of CD2+ lymphocytes which may contribute to the peripheral lymphocytopenia after OKT3.

Interleukin-6 in CAPD patients without peritonitis: relationship to the intrinsic permeability of the peritoneal membrane.

We investigated whether day to day changes in the transport characteristics of the peritoneal membrane to macromolecules in patients treated with CAPD, were related to the levels of interleukin-6 (IL-6) in the effluent of an overnight dwell. Four stable CAPD patients without peritonitis collected all "nightbags" on consecutive days during 2 months for the determination of peritoneal IgG clearance. Serum samples were obtained weekly. IL-6 was determined in the effluent on all occasions where the IgG clearance was less than mean - SD or greater than mean + SD. On these days clearances of beta 2-microglobulin, albumin and alpha 2-macroglobulin were determined as well, to calculate the peritoneal restriction coefficient, i.e. the slope of the power relationship between protein clearances and their free diffusion coefficient in water. This coefficient was used as a parameter of the intrinsic permeability of the membrane. IL-6 was measured by a sensitive and specific bioassay, using the B13.29, subclone 9.9 hybridoma cell assay. Dialysate IL-6 was measured on 43 occasions when IgG clearance was high and on 37 occasions when IgG clearance was low. In all 4 patients indirect evidence was found for local production of IL-6 within the peritoneal cavity: mean dialysate/serum ratios were 15 to 452 times higher than could be expected when IL-6 would enter the dialysate by diffusion only. The patient with the highest dialysate/serum ratio showed higher clearances of albumin, IgG and alpha 2-macroglobulin than the other 3 patients (p less than 0.001) and a lower restriction coefficient (p less than 0.001), indicating a high intrinsic permeability.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunosuppressive drugs in clinical medicine.

Immunosuppressive drugs are agents capable of suppressing the development of at least one type of immune response in vivo at doses with minimal side-effects. Some characteristics regarding the mechanism of action of corticosteroids, azathioprine, cyclophosphamide, cyclosporine and monoclonal antibodies anti-CD3 are reviewed. Corticosteroids induce a redistribution of lymphocytes and display an anti-inflammatory effect; the immunosuppressive effect of azathioprine seems to consist mainly of its suppression of the inflammatory response; cyclophosphamide and cyclosporine influence the immune system itself and anti-CD3 monoclonal antibodies suppress cellular immunity fairly specifically. Finally, a brief summary of their use in renal disease, systemic vasculitis and connective tissue diseases is given.

[Immunology in clinical practice. VI. Current immunosuppressive drugs]. / Immunologie in de medische praktijk. VI. Nieuwe immunosuppressieve geneesmiddelen.

Immunosuppressive drugs are agents capable of modulating at least one type of immune response in vivo at doses with tolerable side-effects. Classical immunosuppressive drugs include corticosteroids, azathioprine, cyclophosphamide, methotrexate and cyclosporine. In the past two years tacrolimus and mycophenolate mofetil were registered as immunosuppressive drugs. Tacrolimus interferes with the calcium-dependent signal transduction of T-lymphocytes. Mycophenolate mofetil is an inhibitor of purine synthesis by inhibition of the enzyme inosine monophosphate dehydrogenase. Both tacrolimus and mycophenolate mofetil have proven efficacy in both prevention and treatment of acute allograft rejection. The new drugs are stronger than the classical ones but do not cause more adverse reactions. The value in clinical medicine of some new, promising immunosuppressive drugs, i.e. sirolimus (rapamycin), mizoribine, brequinar and leflunomide remains to be proven.

[Immunology in medical practice. I. Introduction]. / Immunologie in de medische praktijk. I. Inleiding.

Fundamental immunology has seen a tremendous development in the past decades. This has resulted in a large body of knowledge, part of which has led to applications in laboratory diagnosis, but of which little has made its way to the clinic in terms of new therapies. The progress in understanding pathogenesis of diseases is also slow. This journal is planning a series of articles that highlight the recent achievements of immunology and their consequences for understanding and treating disease.

[Immunology in medical practice. XXX. Organ transplantation: indications and results]. / Immunologie in de medische praktijk. XXX. Orgaantransplantatie: indicaties en resultaten.

During the past 30 years, solid organ transplantation has developed into a routine medical procedure. Currently, one-year transplant survival rates for kidney, heart, liver and pancreas are between 80 and 90%; for most organs, the long-term results are fair with 5-year survival rates of 60%. Inclusion criteria for potential recipients have become less stringent. These days, potential recipients are rarely excluded on the basis of their calendar age alone. The development of more and stronger immunosuppressive drugs has facilitated transplantation across wider immunological differences between donor and recipient with good results. While the number of patients on the waiting lists for organ transplantation increased, the number of organs offered for donation decreased. This has resulted in waiting times of several years for most organ transplantations. While the short-term outcome has improved significantly over the past decades, the long-term outcome has not. Most renal transplants, for example, are lost due to chronic rejection. The challenge for the future will be to improve the long-term outcome of organ transplantation and to decrease the morbidity associated with chronic immunosuppressive therapy.