Rationale: Cytomegalovirus (CMV), which is one of the most common infections after lung transplantation, is associated with chronic lung allograft dysfunction and worse post-transplantation survival. Current approaches for at-risk patients include a fixed duration of antiviral prophylaxis despite the associated cost and side effects.Objectives: We sought to identify a specific immunologic signature that predicted protection from subsequent CMV.Methods: CMV-seropositive lung transplantation recipients were included in the discovery (n = 43) and validation (n = 28) cohorts. Polyfunctional CMV-specific immunity was assessed by stimulating peripheral blood mononuclear cells with CMV pp65 or IE-1 peptide pools and then by measuring T-cell expression of CD107a, IFN-g, tumor necrosis factor-a (TNF-a), and IL-2. Recipients were prospectively monitored for subsequent viremia. A Cox proportional hazards regression model that considered cytokine responses individually and in combination was used to create a predictive model for protection from CMV reactivation. This model was then applied to the validation cohort.Measurements and Main Results: Using the discovery cohort, we identified a specific combination of polyfunctional T-cell subsets to pp65 that predicted protection from subsequent CMV viremia (concordance index 0.88 [SE, 0.087]

Muscle specific tyrosine kinase myasthenia gravis (MuSK MG) is a form of autoimmune MG that predominantly affects women and has unique clinical features, including prominent bulbar weakness, muscle atrophy, and excellent response to therapeutic plasma exchange. Patients with MuSK MG have predominantly IgG4 autoantibodies directed against MuSK on the postsynaptic muscle membrane. Lymphocyte functionality has not been reported in this condition. The goal of this study was to characterize T-cell responses in patients with MuSK MG. Intracellular production of IFN-gamma, TNF-alpha, IL-2, IL-17, and IL-21 by CD4+ and CD8+ T-cells was measured by polychromatic flow cytometry in peripheral blood samples from 11 Musk MG patients and 10 healthy controls. Only one MuSK MG patient was not receiving immunosuppressive therapy. Regulatory T-cells (Treg) were also included in our analysis to determine if changes in T cell function were due to altered Treg frequencies. CD8+ T-cells from MuSK MG patients had higher frequencies of polyfunctional responses than controls, and CD4+ T-cells had higher IL-2, TNF-alpha, and IL-17. MuSK MG patients had a higher percentage of CD4+ T-cells producing combinations of IFN-gamma/IL-2/TNF-gamma, TNF-alpha/IL-2, and IFN-gamma/TNF-alpha. Interestingly, Treg numbers and CD39 expression were not different from control values. MuSK MG patients had increased frequencies of Th1 and Th17 cytokines and were primed for polyfunctional proinflammatory responses that cannot be explained by a defect in Treg function or number.

†Palmer and Weinhold contributed equally to the manuscript.Cytomegalovirus (CMV) is a common opportunistic infection after lung transplant. Despite effective antiviral medications to treat CMV, invasive CMV disease contributes to lung allograft dysfunction and worse survival. Efforts to prevent CMV have led to the use of valganciclovir prophylaxis for increasingly longer periods after transplant. A pivotal concern with long-term antiviral prophylaxis is that it may prevent or delay the development of CMV-specific immunity and increase the subsequent risk of late onset disease. To address this issue, we conducted a pilot study to determine if CMV-specific immunity was detectable in lung transplant recipients at risk for CMV while on antiviral prophylaxis. Utilizing polychromatic flow cytometry panels, CMV-specific immunity was determined by peripheral blood CD4 and CD8 T cell expression of cytokines in response to the HLA restricted CMV peptides pp65 and IE-1. We determined CMV seropositive lung transplant recipients on valganciclovir for a median of 6 months from transplant have a detectable polyfunctional CMV-specific T cell response which is comparable to seropositive recipients not on antiviral medications and to healthy seropositive nontransplant controls. Thus, valganciclovir prophylaxis does not appear to impair the development of CMV-specific immunity in lung transplantation.

Accurate enumeration of CD34+ stem cells is important in assessing the need for continued mobilization and subsequent apheresis collections. We compared two new analysis systems, ProCOUNT (Becton Dickinson Immunocytometry Systems) and IMAGN 2000 STELLer (Biometric Imaging, Inc.) with our current (3-Color) flow cytometry-based method. The ProCOUNT system uses an absolute counting tube, which contains reference beads and a specific (multiple) gating strategy to determine an absolute count. The STELLer assay combines microvolume fluorimetry and automated analysis software to determine an absolute count. To evaluate linearity and reproducibility, peripheral blood was spiked with CD34+ cells (KG1a cell line). Three dilution series (measured at approximately equal to 0, 5, 10, 25, 50, and 100 CD34+ cells/microliter) were analyzed by each method. Analysis of predicted versus actual CD34+ concentration showed excellent correlation with all methods (r2 > or = 0.97, slope 0.98-1.04). To further assess precision, two PBSC samples, at approximately 200 and 800 CD34+ cells/microliter, respectively, were analyzed 10 times by each method. Coefficients of variation for the precision analysis of these samples were 5.1%-6.4% and 5.4%-12.3%, respectively. To assess overall performance, 75 patient specimens were analyzed. Excellent correlation (r2 values of 0.89-0.98) was observed among all three methods. We conclude that the three methods provide comparable linearity and reproducibility.