IL-2 producing memory CD4(+) T lymphocytes are closely associated with the generation of IgG-secreting plasma cells

The role of specific CD4(+) T cell subsets in the induction of Immoral immune responses in humans is largely unknown. In this study, the generation of hepatitis B surface Ag-specific CD4(+) T lymphocytes following vaccination was closely monitored and characterized at the single-cell level. The appearance and absolute numbers of hepatitis B surface Ag-specific IL-2 producing effector memory CD4(+) T lymphocytes was solely and tightly related to Ab titers reached. This relation remained present many years after vaccination. Subsequently, a relation was found between Ab titers and number of IL-2 producing memory CD4(+) T lymphocytes for various other Ags. These observations matched the findings of an in vitro assay, using different T cell subsets to induce B cell differentiation into IgG-producing plasma cells. By depleting for IL-2 producing memory T cells, we demonstrated that these cells are important for B cell differentiation into IgG-producing plasma cells. Finally, blocking the action of IL-2 with an IL-2R-alpha Ab inhibited the differentiation of B lymphocytes into IgG-producing plasma cells. Based on these findings, we conclude that the development of Ag-specific IL-2-producing memory T cells appears to be essential for the development of IgG-secreting plasma cells in humans

Local application of FTY720 to the lung abrogates experimental asthma by altering dendritic cell function

Airway DCs play a crucial role in the pathogenesis of allergic asthma, and interfering with their function could constitute a novel form of therapy. The sphingosine 1-phosphate receptor agonist FTY720 is an oral immunosuppressant that retains lymphocytes in lymph nodes and spleen, thus preventing lymphocyte migration to inflammatory sites. The accompanying lymphopenia could be a serious side effect that would preclude the use of FTY720 as an antiasthmatic drug. Here we show in a murine asthma model that local application of FTY720 via inhalation prior to or during ongoing allergen challenge suppresses Th2-dependent eosinophilic airway inflammation and bronchial hyperresponsiveness without causing lymphopenia and T cell retention in the lymph nodes. Effectiveness of local treatment was achieved by inhibition of the migration of lung DCs to the mediastinal lymph nodes, which in turn inhibited the formation of allergen-specific Th2 cells in lymph nodes. Also, FTY720-treated DCs were intrinsically less potent in activating naive and effector Th2 cells due to a reduced capacity to form stable interactions with T cells and thus to form an immunological synapse. These data support the concept that targeting the function of airway DCs with locall

Lung transplant patients show a dissimilar peripheral b-cell subset ratio compared with healthy controls

Objectives: Lung transplant is a last treatment option for patients with end-stage pulmonary disease. Chronic lung allograft dysfunction, which generally manifests as bronchiolitis obliterans syndrome, is a major long-term survival limitation. Bronchiolitis obliterans syndrome is diagnosed when forced expiratory volume in 1 second declines > 20% in the absence of known causes. B cells can either contribute or restrain the development of bronchiolitis obliterans syndrome (eg, via induction of alloimmune antibodies, regulation of cellular immunity, and induction of tolerance). Here, we explored how peripheral B-cell subsets were altered in lung transplant recipients with bronchiolitis obliterans syndrome. Materials and Methods: Fresh whole blood samples were analyzed from 42 lung transplant recipients, including 17 with bronchiolitis obliterans syndrome; samples from these groups were compared with 10 age-matched healthy control samples. B-cell subsets were analyzed using flow cytometry, and relative distributions of subsets were compared. Changes in forced expiratory volume in 1 second were also determined. Results: Absolute B-cell count was significantly increased in transplant recipients with bronchiolitis obliterans syndrome. Transitional (CD24+CD38+) and naïve (CD27-IgD+) B cells were decreased in lung transplant patients, with transitional B cells almost absent in those with bronchiolitis obliterans syndrome. Double-negative (CD27-IgD-) memory B cells were significantly increased (P < .001). No differences were found for plasmablasts (CD38+CD24-) and switched (CD27+IgD-) and non-switched (CD27+IgD+) memory B cells. Correlation analyses showed positive correlations between lung function and naïve B cells in transplant recipients (P = .0245; r =-0.458). Conclusions: Peripheral B-cell count and subset distribution were altered in lung transplant recipients with and without bronchiolitis obliterans syndrome compared with healthy controls. Transitional and naïve B-cell decreases may be caused by differentiation toward double-negative B-cells, which were increased. The correlation between forced expiratory volume and naïve B cells during follow-up care may be clinically interesting to investigate