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Dale T Umetsu

Publications and source records attributed to Dale T Umetsu.

40 records · Page 3Linked to original sources
PubMed2002

Critical role of CD81 in cognate T-B cell interactions leading to Th2 responses.

We previously demonstrated that CD81-/- mice fail to develop Th2-biased immune responses and allergen-induced airway hyper-reactivity. Because CD81 is expressed on both activated T and on B cells, we examined the role of CD81 expression by each cell type. We established an in vitro system by backcrossing the CD81 deletion to TCR transgenic (Tg) mice and to BCR Tg mice. Here we demonstrate that CD81 expression by T cells is critical for their induction of IL-4 synthesis by B cells. CD81-/- TCR Tg T cells were impaired in IL-4 production compared to CD81+/+ TCR Tg T cells, whereas CD81-/- and CD81+/+ BCR Tg B cells induced equivalent amounts of IL-4 in CD81+/+ TCR Tg T cells. CD81-/- TCR Tg T cells expressed reduced levels of ICOS, GATA-3, STAT6 and phosphorylated STAT6 when activated by antigen-presenting B cells. Taken together, these results indicate that CD81 expression by T cells greatly enhances cognate T-B cell interactions and greatly augments intracellular activation pathways leading to Th2 polarization.

Animals↗
PubMed2002

Critical role of B cells in the development of T cell tolerance to aeroallergens.

Respiratory exposure to allergen induces the development of allergen-specific CD4(+) T cell tolerance that effectively protects against the development of allergic-sensitization and T(h)2-biased immunity. The establishment of T cell unresponsiveness to aeroallergens is an active process preceded by a transient phase of T cell activation that requires T cell co-stimulation and is critically influenced by the antigen-presenting cell type. In this study we examined the role of B cells in the development of respiratory tolerance following intranasal (i.n.) exposure to a prototypic protein antigen. We found that respiratory exposure of BCR-transgenic (Tg) mice to minute quantities of cognate antigen effectively induced T cell unresponsiveness, indicating that antigen presentation by antigen-specific B cells greatly enhanced the development of respiratory tolerance. In contrast, respiratory T cell unresponsiveness could not be induced in B cell-deficient JHD mice exposed to i.n. antigen, although T cell tolerance developed in JHD mice reconstituted with B cells, suggesting that B cells are required for the induction of respiratory T cell tolerance. Respiratory exposure of BCR-Tg mice to cognate antigen induced activation of antigen-specific T cells and partial activation of antigen-specific B cells, as demonstrated by enhanced expression by B cells of class II MHC and B7 molecules but lack of antibody secretion. Our data indicate that B cells critically influence the immune response to inhaled allergens and are required for the development of allergen-specific T cell unresponsiveness induced by respiratory allergen.

Administration, Intranasal↗
PubMed2002

Agreement among measures of asthma status: a prospective study of low-income children with moderate to severe asthma.

BACKGROUND: Because no validated "gold standard" for measuring asthma outcomes exists, asthma interventions are often evaluated using a large number of disease status measures. Some of these measures may be redundant, whereas others may be complementary. Use of multiple outcomes may lead to ambiguous results, increased type I error rates, and be an inefficient use of resources including caregiver and patient/participant time and effort. Understanding the relationship between these measures may facilitate more parsimonious and valid evaluation strategies without loss of information. OBJECTIVE: To assess the relationships between multiple measures of asthma disease status over time. DESIGN/METHODS: We used data from a randomized, controlled trial of a comprehensive disease management program involving 119 disadvantaged inner-city children aged 5 to 12 years with moderate to severe asthma. Spearman correlations were calculated between the following asthma disease status measures: parent-reported disease symptoms, parent-reported health care utilization, functional health status using the American Academy of Pediatrics' validated Child Health Survey for Asthma (CHSA), diary data (symptom scores, night wakings, and bronchodilator use), and pulmonary function tests at baseline, 32 weeks, 52 weeks, and changes from baseline to 52 weeks. RESULTS: Ninety-four (79%) of randomized patients participated at baseline and 52 weeks. Completion rates for outcome measures ranged from 79% (CHSA, spirometry data) to 64% (diary data). At baseline, asthma symptoms, health care utilization, and individual domains from the CHSA were significantly correlated (r = 0.21-0.53). These correlations were stable over the 52-week follow-up. Forced expiratory volume in 1 second and diary data did not correlate to any other measures at baseline, and these measures correlated only inconsistently with other measures at 32 weeks and 52 weeks. Baseline to 52-week changes in asthma symptoms, utilization, and the CHSA domains were significantly correlated (0.22-0.56), as were baseline to 52-week changes in symptom days, night wakings, and the CHSA domains (r = 0.24-0.64). Baseline to 52-week changes in forced expiratory volume in 1 second and diary data did not correlate with other measures. CONCLUSIONS: These results suggest that asthma status and change in asthma status over time after introduction of a disease management intervention are best characterized by parent-reported symptoms, parent-reported utilization, and functional health status measures. Asthma diaries and pulmonary function tests did not seem to provide additional benefit, although they may play an important role in individual patient management. Our findings suggest a parsimonious evaluation strategy would include collection of key data elements regarding symptoms, utilization, and functional health status only, without loss of vital response information.

Asthma↗