Airway inflammation associated with asthma is characterized by massive infiltration of eosinophils, mediated in part by specific chemoattractant factors produced in the lung. Allergen-specific Th2 ...cells appear to play a central role in asthma; for example, adoptively transferred Th2 cells induced lung eosinophilia associated with induction of specific chemokines. Interestingly, Th2 supernatant alone administered intranasally to naive mice induced eotaxin, RANTES, monocyte-chemotactic protein-1, and KC expression along with lung eosinophilia. We tested the major cytokines individually and found that IL-4 and IL-5 induced higher levels of macrophage-inflammatory protein-1alpha and KC; IL-4 also increased the production of monocyte-chemotactic protein-1; IL-13 and IL-4 induced eotaxin. IL-13 was by far the most potent inducer of eotaxin; indeed, a neutralizing anti-IL-13 Ab removed most of the eotaxin-inducing activity from Th2 supernatants, although it did not entirely block the recruitment of eosinophils. While TNF-alpha did not stimulate eotaxin production by itself, it markedly augmented eotaxin induction by IL-13. IL-13 was able to induce eotaxin in the lung of JAK3-deficient mice, suggesting that JAK3 is not required for IL-13 signaling in airway epithelial cells; however, eosinophilia was not induced in this situation, suggesting that JAK3 transduces other IL-13-mediated mechanisms critical for eosinophil recruitment. Our study suggests that IL-13 is an important mediator in the pathogenesis of asthma and therefore a potential target for asthma therapy.
Highlights • Adults had higher CD4+ T-cell responses to Spn and NT Hi antigens compared to very young children. • CD4+ T-cell responses of very young children to Spn and NT Hi antigens were Th-2 ...predominant. • Very young children have reduced Th1 and Th2 responses similar to neonates. • IL-17a producing CD4+ T-cells were rarely detected in response to Spn and NT Hi antigens. • Memory phenotypic profiles of antigen-induced CD4+ T-cells were divergent in adults and children.
Background. We sought to understand why some children respond poorly to vaccinations in the first year of life. Methods. A total of 499 children (6–36 months old) provided serum and peripheral blood ...mononuclear cell samples after their primary and booster vaccination. Vaccine antigen-specific antibody levels were analyzed with enzyme-linked immunosorbent assay, and frequency of memory B cells, functional T-cell responses, and antigen-presenting cell responses were assessed in peripheral blood mononuclear cell samples with flow cytometric analysis. Results. Eleven percent of children were low vaccine responders, defined a priori as those with subprotective immunoglobulin G antibody levels to ≥66% of vaccines tested. Low vaccine responders generated fewer memory B cells, had reduced activation by CD4+ and CD8+ T cells on polyclonal stimulation, and displayed lower major histocompatibility complex II expression by antigen-presenting cells. Conclusions. We conclude that subprotective vaccine responses in infants are associated with a distinct immunologic profile.
The incorporation of rituximab, a chimeric anti-CD20 monoclonal antibody, into the therapeutic armamentarium for patients with follicular lymphoma (FL) has significantly improved treatment outcome ...for such patients. Despite the almost universal application of this therapy, however, its exact mechanism of action has not been completely defined. One proposed mechanism is that of a “vaccinal” effect, whereby FL cell kill by rituximab results in the elicitation of an FL-specific T-cell response. The demonstration that rituximab can even elicit such a response in patients has, to our knowledge, never been shown. We analyzed the response against the immunoglobulin expressed by the FL before and after rituximab monotherapy in 5 FL patients and found an increase in FL idiotype–specific T cells after rituximab in 4 of 5 patients. Our data thus provide “proof of principle” for the ability of passive immunotherapy with rituximab to elicit an active FL-specific cellular response.
Background Amphiregulin, a member of the epidermal growth factor family, is expressed by activated mouse TH 2 cells. Amphiregulin produced by mouse hematopoietic cells contributes to the elimination ...of a nematode infection by a type 2 effector response. Objective To identify the human peripheral blood cell population expressing amphiregulin. Methods Amphiregulin-expressing cells were identified by flow cytometry of cell surface markers and histologic staining. Histamine and amphiregulin in supernatants were measured by enzyme immunoassay. Quantitative real-time PCR was used to measure mRNA expression. Results Stimulation of human PBMCs by anti-CD3 + anti-CD28 antibodies induced expression of amphiregulin mRNA and protein by a non–T-cell population. The amphiregulin-producing cells were basophils, as judged by morphology and expression of CD203c and CD123 (IL-3 receptor α chain). Activated mouse basophils also produced amphiregulin. Amphiregulin expression by basophils in response to anti-TCR stimulation required IL-3 produced by T cells, and IL-3 alone induced high levels of amphiregulin expression by purified basophils. Amphiregulin was expressed at much higher levels when human basophils were stimulated by IL-3 than by IgE cross-linking, whereas the opposite was true for IL-4 expression and histamine release. Heparin-binding epidermal growth factor–like growth factor was also expressed by IL-3–stimulated human basophils. PBMCs from human subjects with asthma contained significantly higher numbers of basophils able to produce amphiregulin compared with controls with or without allergy. Conclusion IL-3 can induce basophils to express high levels of amphiregulin, which may contribute to tissue remodeling during type 2 immune responses such as asthma.
Recent advances in understanding CD4+ T‐cell differentiation suggest that previous models of a few distinct, stable effector phenotypes were too simplistic. Although several well‐characterized ...phenotypes are still recognized, some states display plasticity, and intermediate phenotypes exist. As a framework for reexamining these concepts, we use Waddington's landscape paradigm, augmented with explicit consideration of stochastic variations. Our animation program “LAVA” visualizes T‐cell differentiation as cells moving across a landscape of hills and valleys, leading to attractor basins representing stable or semistable differentiation states. The model illustrates several principles, including: (i) cell populations may behave more predictably than individual cells; (ii) analogous to reticulate evolution, differentiation may proceed through a network of interconnected states, rather than a single well‐defined pathway; (iii) relatively minor changes in the barriers between attractor basins can change the stability or plasticity of a population; (iv) intrapopulation variability of gene expression may be an important regulator of differentiation, rather than inconsequential noise; (v) the behavior of some populations may be defined mainly by the behavior of outlier cells. While not a quantitative representation of actual differentiation, our model is intended to provoke discussion of T‐cell differentiation pathways, particularly highlighting a probabilistic view of transitions between states.
Biological differences of interest in large, high-dimensional flow cytometry datasets are often obscured by undesired variations caused by differences in cytometers, reagents, or operators. Each ...variation type requires a different correction strategy, and their unknown contributions to overall variability hinder automated correction. We now describe swiftReg, an automated method that reduces undesired sources of variability between samples and particularly between batches. A high-resolution cluster map representing the multidimensional data is generated using the SWIFT algorithm, and shifts in cluster positions between samples are measured. Subpopulations are aligned between samples by displacing cell parameter values according to registration vectors derived from independent or locally-averaged cluster shifts. Batch variation is addressed by registering batch control or consensus samples, and applying the resulting shifts to individual samples. swiftReg selectively reduces batch variation, enhancing detection of biological differences. swiftReg outputs registered datasets as standard .FCS files to facilitate further analysis by other tools.
Background. Respiratory syncytial virus (RSV) infection is the most common respiratory viral infection resulting in hospitalizations in infants worldwide. Illness severity is likely multifactorial; ...however, unlike other viral infections, both type 1 and type 2 cytokine responses have been implicated in severe disease. Methods. We measured RSV-specific cytokine responses ex vivo during primary RSV infection in the blood of 18 infants with polymerase chain reaction—confirmed RSV infection. To focus on primary RSV infection, subjects were all <9 months old. RSV-specific cytokine responses were measured at 3 time points during acute primary RSV infection and at 1 memory time point 3–6 months later. Results. RSV-specific interferon (IFN)—γ responses were detected in 10 of 18 of infants. Infants with mild disease had higher RSV-specific IFN-γ memory responses than did those with moderate or severe disease. No consistent correlations between RSV-specific IFN-γ responses and corticosteroid administration were observed. RSV-specific interleukin (IL)—4 or IL-5 responses to primary RSV infection were detectable in 5 of 18 and 8 of 15 infants, respectively. Conclusions. During primary RSV infection, many infants demonstrated RSV-specific IFN-γ responses. The strongest IL-4 and IL-5 responses were detected in 3 infants with severe disease, suggesting that type 2 responses may contribute to the pathogenesis of severe disease.
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