Characterization of human memory CD4(+) T-cell responses to the dog allergen Can f 4.

BACKGROUND: The recently identified dog lipocalin allergen Can f 4 is an important respiratory allergen. OBJECTIVE: We sought to comprehensively characterize the memory CD4(+) T-cell responses of allergic and nonallergic subjects to Can f 4. METHODS: Can f 4-specific CD4(+)CD45RO(+) T-cell lines (TCLs) from allergic and healthy subjects were established and characterized by their functional and phenotypic properties. The epitope specificity of the TCLs was tested with 48 overlapping 16-mer peptides spanning the sequence of Can f 4. HLA restriction of the specific TCLs and the binding capacity of the epitope-containing peptides to common HLA class II molecules were studied. RESULTS: Can f 4-specific memory CD4(+) TCLs were obtained at an 8-fold higher frequency from allergic than from nonallergic subjects. Functionally, the TCLs of allergic subjects exhibited a higher T-cell receptor avidity and expression of CD25 and predominantly produced IL-4 and IL-5. The TCLs of nonallergic subjects mostly secreted IFN-γ and IL-10, with high CXCR3 expression. Several distinct T-cell epitope regions along the allergen were identified. Importantly, the peptides from the region between amino acids 43 and 67 showed promiscuous HLA-binding capacity and induced memory CD4(+) T-cell responses in 90% of the allergic donors. CONCLUSION: Productive TH2-deviated memory T-cell responses to Can f 4 are observed in allergic but not nonallergic subjects. A 19-mer peptide sequence covering the core of the immunodominant region of the allergen is a potential target for the development of peptide-based allergen immunotherapy.

Human CD4+ T cell responses to the dog major allergen Can f 1 and its human homologue tear lipocalin resemble each other.

Lipocalin allergens form a notable group of proteins, as they contain most of the significant respiratory allergens from mammals. The basis for the allergenic capacity of allergens in the lipocalin family, that is, the development of T-helper type 2 immunity against them, is still unresolved. As immunogenicity has been proposed to be a decisive feature of allergens, the purpose of this work was to examine human CD4+ T cell responses to the major dog allergen Can f 1 and to compare them with those to its human homologue, tear lipocalin (TL). For this, specific T cell lines were induced in vitro from the peripheral blood mononuclear cells of Can f 1-allergic and healthy dog dust-exposed subjects with peptides containing the immunodominant T cell epitopes of Can f 1 and the corresponding TL peptides. We found that the frequency of Can f 1 and TL-specific T cells in both subject groups was low and close to each other, the difference being about two-fold. Importantly, we found that the proliferative responses of both Can f 1 and TL-specific T cell lines from allergic subjects were stronger than those from healthy subjects, but that the strength of the responses within the subject groups did not differ between these two antigens. Moreover, the phenotype of the Can f 1 and TL-specific T cell lines, determined by cytokine production and expression of cell surface markers, resembled each other. The HLA system appeared to have a minimal role in explaining the allergenicity of Can f 1, as the allergic and healthy subjects' HLA background did not differ, and HLA binding was very similar between Can f 1 and TL peptides. Along with existing data on lipocalin allergens, we conclude that strong antigenicity is not decisive for the allergenicity of Can f 1.

Health risk assessment of indoor air pollution in Finnish ice arenas.

Poor indoor air quality and epidemic carbon monoxide (CO) and nitrogen dioxide (NO(2)) poisonings due to exhaust emissions from ice resurfacers have been continuously reported from enclosed ice arenas for over 30 years. The health risks in users of Finnish ice arenas were analysed in three ways: (1) evaluation of four cases of epidemic CO poisonings, (2) modelling the association between NO(2) exposure and respiratory symptoms among junior ice hockey players, and (3) estimation of the number of arena users at risk of breathing poor quality air due to non-compliance of ice arenas with recommended abatement measures. The common causes for the CO poisonings involving over 300 subjects were large emissions from propane-fuelled ice resurfacer, small arena volume, negligible ventilation, and very recent opening of the arena. Rhinitis (prevalence 18.3%) and cough (13.7%) during or after training or game were significantly associated with the estimated personal NO(2) exposure of young hockey players (n=793) to average concentrations ranging from 21 to 1176 microg/m(3) in their home arena. During a 6-year follow-up of an intensive information campaign the portion of electric resurfacers increased from 9% to 27%, and that of emission control technology on propane-fuelled resurfacers increased from 13% to 84%. The portion of inadequately ventilated arenas decreased from 34% to 25%. However, 48% of the investigated Finnish ice arenas (n=125) did not fully comply with the non-regulatory recommendations. Consequently, 20000 daily users of ice arenas were estimated to remain in 2001 at risk of breathing poor quality air. Modern small and inadequately ventilated ice arenas pose their users (mostly children and young adults) at risk of breathing poor quality air and suffering from acute adverse health effects. Governmental regulations are needed worldwide to ensure safe sports in enclosed ice arenas.

Interpretation of cough provoked by airway challenges.

STUDY OBJECTIVE: To analyze the cough response to three airway challenges in order to clarify whether the recording of the provoked coughs would be beneficial in the management of asthma. DESIGN: A prospective study. SETTING: University hospital. PARTICIPANTS: Fifteen healthy subjects, 16 steroid-naïve subjects with asthma, and 16 subjects with steroid-treated asthma. INTERVENTIONS: Inhalation challenges with isotonic histamine, hypertonic saline solution, and hypertonic histamine, using an ultrasonic nebulizer and 2-min tidal breathing method. MEASUREMENTS: Airflow parameters were measured with a spirometer, and the coughs were recorded manually. RESULTS: Coughing during the isotonic histamine challenge was associated with the degree of the bronchoconstriction induced. When this was taken into account, the healthy subjects coughed as frequently as the asthmatic subjects. During the two hypertonic challenges, the asthmatic subjects coughed more frequently than did the healthy subjects when the induced bronchoconstriction had not yet developed. At that stage of the hypertonic saline solution challenge, the mean coughing frequency was 0.7 coughs per minute (95% confidence interval [CI], 0.03 to 1.3 coughs per minute) for the healthy subjects, 2.7 coughs per minute (95% CI, 0.8 to 4.5 coughs per minute) for the steroid-naïve asthmatic subjects, and 1.3 coughs per minute (95% CI, 0.6 to 1.9 coughs per minute) for the steroid-treated asthmatic subjects (p = 0.018). For the hypertonic histamine challenge, the respective values were 0.8 coughs per minute (95% CI, 0.4 to 1.2 coughs per minute), 3.6 coughs per minute (95% CI, 2.4 to 4.9 coughs per minute), and 2.1 coughs per minute (95% CI, 1.0 to 3.1 coughs per minute; p = 0.001). This cough did not correlate with airway hyperresponsiveness. CONCLUSIONS: Coughing during isotonic histamine challenge seems to be a manifestation of bronchoconstriction, and recording of the coughs may not provide additional information to airflow measurements. Frequent coughing during hypertonic saline solution and hypertonic histamine challenges in the absence of bronchoconstriction is a pathologic phenomenon. Sensitivity to the cough-provoking effect of hypertonic challenges seems to be enhanced in patients with asthma but unrelated to airway hyperresponsiveness. Therefore, the recording of the provoked coughs during these challenges may add to the information obtained from airflow measurements.

Hypertonicity of the challenge solution may increase the diagnostic accuracy of histamine challenge.

There is significant overlap in the responsiveness to direct airway challenges, such as the histamine challenge, between asthmatic and non-asthmatic subjects, which decreases their accuracy in the diagnosis of asthma. To minimise this overlap, a new test, hypertonic histamine challenge, was developed. Fifteen healthy subjects, 16 subjects with steroid-naive asthma, and 16 asthmatic subjects undergoing inhaled corticosteroid treatment underwent inhalation challenges with hypertonic saline, isotonic histamine, and hypertonic histamine, using an ultrasonic nebuliser and 2-min tidal breathing method. The increase in histamine solution tonicity decreased the histamine PC20 values only in the steroid-naive asthmatic subjects (1.1 (0.5-2.7) vs. 0.5 (0.2-1.2) mg/ml, P = 0.047). Using 1mg/ml as the cut-off value, the sensitivity, specificity, and accuracy of the hypertonic histamine challenge to detect steroid-naive asthma was 81%, 100%, and 90%. The respective values for the isotonic histamine challenge were 56%, 100%, and 77%. Furthermore, there was a statistically significant difference in the hypertonic histamine PC20 between steroid-naive and steroid-treated asthmatic subjects, which could not be detected in the isotonic histamine PC20. The hypertonic histamine PC20 was highly repeatable, with a single determination 95% range of +/-1.35 doubling concentrations. The hypertonic histamine challenge was safe but provoked more cough and throat irritation than the other two challenges. In conclusion, compared with a conventional, isotonic histamine challenge, hypertonic histamine challenge may be more accurate in the diagnosis of asthma and also, more capable to detect the effects of inhaled corticosteroid treatment.