E.H.M. Loonen

Patients on Chronic Hemodialysis Have No Intrinsic Lymphocyte Defect upon Stimulation with Interleukin-2, Interleukin-15 or Tumor Necrosis Factor-Alpha

Background: Patients on chronic hemodialysis (HD) suffer from general immune incompetence, resulting in a high incidence of infectious complications, impaired response to vaccinations and a high incidence of malignancy. Although various abnormalities in T cell function of HD patients have been described, it remains unclear whether this is due to an intrinsic T cell defect. Aim: In the present study we tested the capacity of T cells to proliferate upon stimulation with antigen-presenting cell and T-cell-derived cytokines. Methods: The proliferation capacity of lymphocytes obtained from patients on HD and healthy controls was determined by measuring the proliferation of peripheral blood mononuclear cells (PBMC) after stimulation with rhIL-2, rhIL-15, rhTNF-α, or combination of those cytokines. In all samples the percentage of α/β TCR-positive T cells was measured. Results: After isolation of PBMC the percentage of T cells varied from 70% (before stimulation) to 80% (after stimulation). IL-2, IL-15 and TNF-α all induced PBMC proliferation, while the combination TNF-α plus IL-2 or TNF-α plus IL-15 appeared to be additive. No difference between PBMC from HD patients and controls was found. Conclusion: We conclude that lymphocytes from HD patients have no intrinsic defects in their proliferation capacity after stimulation with IL-2, IL-15 or TNF-α, in vitro, as the increase in counts per minute is predominant.

Failure to down-regulate intragraft cytokine mRNA expression shortly after clinical heart transplantation is associated with high incidence of acute rejection

BACKGROUND Brain-death, ischemia and reperfusion damage have been implicated as initial factors that lead to a cascade of immunologic events that result in allograft rejection in experimental animals. Cytokines are thought to play a central role in this process. Therefore, we evaluated intragraft cytokine mRNA expression at an early stage after clinical heart transplantation and related these data to ischemia, immunosuppression, and rejection. METHODS We sampled endomyocardial biopsies at 30 minutes (EMB 0) and at 1 week (EMB 1) after transplantation from 20 cardiac allograft recipients. Intragraft monocyte chemoattractant protein (MCP-1) and basic fibroblast growth factor (bFGF) mRNA expression levels were quantitatively measured using competitive template Reverse-transcriptase polymerase chain reaction (RT-PCR). RESULTS We measured significantly lower MCP-1 and bFGF mRNA expression levels in EMB 1 compared with EMB 0 (MCP-1, p = 0.006; bFGF, p = 0.019). We found no direct correlation between the cytokine mRNA expression levels in EMB 0 or EMB 1 and ischemic times, induction therapy, or cyclosporine whole-blood trough levels. Patients with a high incidence of acute rejection episodes (>2 in the first year) had higher bFGF mRNA expression levels (p = 0.009) and comparable MCP-1 mRNA expression levels (p = 0.378) at 1 week, compared with patients with a lower rejection incidence. The MCP-1 and bFGF mRNA expression levels in the first week were not associated with the development of graft vascular disease in the first year post-transplant. CONCLUSIONS We found a significant decrease of intragraft MCP-1 and bFGF mRNA expression levels in the first post-operative week. Patients with a high incidence of acute rejection had higher bFGF mRNA expression levels in their first week biopsy. Therefore, we conclude that patients who fail to down-regulate their bFGF mRNA expression early after transplantation are at higher risk for acute rejection.