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After lung transplantation (LTx), circulating mononuclear cell composition and their subsets may be predictive for the bronchiolitis obliterans syndrome (BOS). We investigated the cellular composition in patients developing BOS, or not, by analyzing peripheral blood taken at multiple time points after transplantation. PBMCs of 11 BOS and 39 non-BOS patients were analyzed by FACS for monocytes, dendritic cells, NK-, NKT-, B- and T cells as well as B- and T cell subsets. Analysis of blood samples taken monthly during the first year post-LTx showed that circulating NK, NKT and dendritic cell percentages were not indicative of BOS development, whereas increases in T cells, monocytes and lowered fractions of B cells were related to BOS development. B- and T cell subset analysis at month 5 post-LTx indicated that IgM+IgD- memory B cells and central memory CD8+ T cells were decreased, whereas NKT cells were increased in BOS patients compared to non-BOS patients. Prior to BOS diagnosis, the composition of specific mononuclear cells on a group level differs from patients remaining BOS free. However, given the overlap in percentages of cellular frequencies between the patient groups investigated, this analysis does not allow prediction or risk stratification for development of BOS in individual patients.

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The production of IgG HLA antibodies after lung transplantation (LTx) is considered to be a major risk factor for the development of chronic rejection, represented by the bronchiolitis obliterans syndrome (BOS). It has recently been observed that elevated levels of IgM HLA antibodies also correlates with the development of chronic rejection in heart and kidney transplantation. This study investigates the relationship between IgM and IgG antibodies against HLA and MICA after lung transplantation. Serum was collected from 49 patients once prior to transplantation and monthly for up to 1 year after lung transplantation was analyzed by Luminex to detect IgM and IgG antibodies against HLA and MICA. The presence of either IgM or IgG HLA and/or MICA antibodies prior to or after transplantation was not related to survival, gender, primary disease, or the development of BOS. Additionally, the production of IgG alloantibodies was not preceded by an increase in levels of IgM, and IgM levels were not followed by an increase in IgG. Under current immune suppressive regimen, although the presence of IgM antibodies does not correlate with BOS after LTx, IgM( high) IgG( low) HLA class I antibody titers were observed more in patients with BOS compared to patients without BOS.

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BACKGROUND: Passenger leukocytes of donor origin are transferred to the patient resulting in circulatory microchimerism after lung transplantation (LTx). This chimeric state has been shown to occur in the total leukocyte fraction as well as unseparated peripheral blood mononuclear cells (PBMCs). In this study we determined the microchimerism levels of B cells, monocytes, natural killer (NK) and T cells and dendritic cell (DC) subsets (mDC1, mDC2 and pDC) during the first year after lung transplantation. METHODS: To identify circulating donor cells, 11 donor-patient combinations were selected, which were mismatched for HLA-B8. Analysis consisted of flow cytometry on a minimum of 1 million PBMCs taken monthly up to 1 year after LTx. RESULTS: Levels of microchimerism were found to be stable after LTx for all cell types investigated, although for NK+T cells an above-baseline chimerism of donor cells from the donor lung was observed in the first month after transplantation. Circulating PBMCs consisted of, on average, 0.002%, 1.7%, 0.03% and 0.001% of B cells, monocytes, NK+T cells and DCs, respectively, indicating that overall levels of microchimerism differed between the cell types investigated. In 2 patients no B-cell chimerism and in 1 patient no DC chimerism could be detected. Cell types and DC subsets of recipient origin were normally distributed. Conversely, monocytes, B cells and DCs of donor origin were increased and donor NK+T cells were decreased in number, compared with the recipient ratios. Analysis of circulating recipient DCs showed a normal distribution of mDC1s (70%), mDC2s (5%) and pDCs (25%). However, circulating donor DCs consisted of 80%, 20% and <1% of DC subsets mDC1, MDC2 and pDC, indicating that donor plasmacytoid dendritic cells were not detectable in the circulation. CONCLUSIONS: In the first year after lung transplantation a stable microchimerism was detected for all cell types investigated. However, donor pDCs were consistently absent in all samples investigated, which may be linked with graft rejection often observed after LTx.

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BACKGROUND: The purpose of this study was to determine the utility of post-transplant serum soluble CD30 levels as a biomarker for the development of the bronchiolitis obliterans syndrome (BOS) after lung transplantation during a tacrolimus/mycophenolate mofetil-based regimen. METHODS: Soluble CD30 (sCD30) concentrations were measured prior to transplantation and in 175 samples taken after transplantation in 7 patients developing BOS and 7 non-BOS patients closely matched for age, underlying diseases, follow-up and gender. RESULTS: High pre-transplant sCD30 levels dropped significantly after lung transplantation, but in the post-transplant samples no differences could be detected between patients developing BOS or not, and no changes were found prior to or during the development of BOS. CONCLUSIONS: After transplantation, sCD30 levels are consistently suppressed, but BOS is not prevented, indicating that sCD30 cannot be used as a biomarker to predict BOS after transplantation in the regimen employed.

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BACKGROUND: The development of bronchiolitis obliterans syndrome (BOS) after lung transplantation is associated with viral infections. Natural killer (NK) cells are involved in the lysis of viral infected cells, and their activation is largely controlled by activating and inhibitory killer immunoglobulin-like receptors (KIRs). We hypothesized that KIR ligand incompatibility and recipients' individual KIRs could influence the development of BOS and the incidence of cytomegalovirus reactivation after lung transplantation. METHODS: The KIR gene contents were determined in 48 patients who received a lung transplant, and human leukocyte antigen (HLA)-Cw and HLA-Bw4 typing was performed on their respective donors. RESULTS: BOS developed in 7 patients and cytomegalovirus reactivation occurred in 16. BOS developed in 5 of 19 patients homozygous for KIR haplotype A compared with 2 of 27 patients with KIR haplotype AB and B (homozygous; p = 0.03; log-rank test). In none of the patients with BOS was the activating KIR2DS5 gene detected, whereas it was present in 35% of patients without BOS (p = 0.04; log-rank test). No correlation was found between KIR gene content and cytomegalovirus reactivation. CONCLUSION: Our results suggest that the lack of activating KIRs may play an important role in the development of BOS but not in the control of cytomegalovirus reactivation after lung transplantation.

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