Sero-prevalence study of IgE responses to allergens from Malaysian house dust (HDM) and storage mites (SM)

Allergens of Dermatophagoides and Blomia species are well-characterized but not for other species. This study was conducted to determine the prevalence of allergic sensitization to house dust (HDM) and storage mites (SM). One hundred adult subjects (aged > 18) were recruited. The mite specific IgE of all allergic subjects were higher compared with healthy subjetcs despite being not statistically significant except for D. farinae and G. malaysiensis. The mean serum IgE levels against HDM and SM for allergic subjects were significantly higher compared with those in healthy subjects. They were mainly sensitized to Dermatophagoides farinae (35%) and Glycycometus malaysiensis (37%). Immunoblots revealed not all allergic subjects showed positive immuno-reactivity against the mites tested. Single or multiple bands were observed for different species. The subjects were commonly sensitized to Group 2 (9-12 kDa), 10 (38 kDa) and 18 (40-48 kDa) allergens. Twenty-one out of 60 allergic subjects were sensitized to either one or more species. The majority of them (71%) were sensitized to single species. The allergic subjects were mainly sensitized to D. pteronyssinus, followed by Tyrophagus putrecentiae and Aleuroglyphus ovatus. Seven were solely sensitized to HDM while 10 were solely sensitized to SM. Four subjects were sensitized to both. Preadsorption study revealed no cross-reactivity. There was difference between the prevalence and reactivity to allergens of HDM and SM in these subjects. Both ELISA and immunoblot did not correlate well but can complement each other in improving the detection of mite allergens to the species level.

Lack of neutrophil degranulation in low-dose endotoxin inhalation based on a novel intracellular assay.

To study the nature of endotoxin or lipopolysaccharide (LPS) induced inflammation, we developed a method of quantifying intracellular human neutrophil elastase (HNE) in lysed sputum polymorphs as a means to study the degranulation status of LPS-recruited neutrophils. Induced sputum, blood and exhaled nitric oxide (NO) were collected from 10 healthy non-atopic human subjects after inhaling a single 15 microg dose of Escherichia coil LPS in an open study. At 6 hours, LPS inhalation caused significant increase of sputum and blood neutrophils but without parallel increase in myeloperoxidase, HNE or interleukin-8 (IL-8) in sputum sol and blood, or exhaled NO. Intracellular HNE in lysed sputum polymorphs or purified blood neutrophils did not show any significant changes between inhaled LPS and saline, nor was there any appreciable change in percentage HNE release induced by N-Formyl-Met-Leu-Phe (fMLP) in vitro. We concluded that in healthy humans, the transient neutrophilic inflammation induced by a single dose of inhaled 15 microg LPS is mainly characterized by cell recruitment, not enhanced secretion of granular mediators or increased exhaled NO based on our experimental conditions.

Sputum induction in corticosteroid-dependant asthmatics: risks and airway cellular profile.

Sputum induction with nebulized hypertonic saline is increasingly being used to evaluate airway inflammation. We investigated the procedure-associated risk in 16 asthmatics that were still symptomatic despite on high doses of regular corticosteroid (CS) therapy (7 on daily inhaled CS > or = 800 microg budesonide or equivalent; 9 on additional daily oral CS) and their sputum cellular profile. For comparison, 12 mild stable asthmatics and 10 normal healthy subjects were included. All subjects inhaled 3%, 4% and 5% hypertonic saline sequentially via ultrasonic nebulizer as a means to induce sputum. Maximal percentage fall of Forced Expiratory Volume on One Second (FEV1) during sputum induction was significantly greater in CS-dependent asthmatics (median % [IQR]: 16.0 [11.0-32.3]) than in mild asthmatics (5.3 [4.2-10.8], p = 0.002] and in normal subjects (4.6 [3.4-6.4]), p = 0.0001). The maximal percentage FEV1 fall was inversely correlated with baseline FEV1 (Rs= -0.69; p < 0.0001). Compared to mild asthmatics, induced sputum from CS-dependant asthmatics had proportionately fewer eosinophils (2.2 [0.8-7.0] versus 23.3% [10.7-46.3], p = 0.003) and greater neutrophils (64.2 [43.9-81.2] versus 28.7 [19.0-42.6], p = 0.009). Sputum neutrophils showed a significant inverse correlation to FEV1 (Rs = -0.51, p = 0.01). We concluded that sputum induction using nebulized hypertonic saline should be performed with caution in CS-dependant asthmatics. The airway cellular profile observed suggests that the immunopathology underlying CS-dependant asthmatics may be different or a consequence of CS therapy.

A comparison of sputum induction methods: ultrasonic vs compressed-air nebulizer and hypertonic vs isotonic saline inhalation.

Airway inflammation can be demonstrated by the modem method of sputum induction using ultrasonic nebulizer and hypertonic saline. We studied whether compressed-air nebulizer and isotonic saline which are commonly available and cost less, are as effective in inducing sputum in normal adult subjects as the above mentioned tools. Sixteen subjects underwent weekly sputum induction in the following manner: ultrasonic nebulizer (Medix Sonix 2000, Clement Clarke, UK) using hypertonic saline, ultrasonic nebulizer using isotonic saline, compressed-air nebulizer (BestNeb, Taiwan) using hypertonic saline, and compressed-air nebulizer using isotonic saline. Overall, the use of an ultrasonic nebulizer and hypertonic saline yielded significantly higher total sputum cell counts and a higher percentage of cell viability than compressed-air nebulizers and isotonic saline. With the latter, there was a trend towards squamous cell contaminations. The proportion of various sputum cell types was not significantly different between the groups, and the reproducibility in sputum macrophages and neutrophils was high (Intraclass correlation coefficient, r [95%CI]: 0.65 [0.30-0.91] and 0.58 [0.22-0.89], p < 0.001). Overall changes in median FEV, were small and comparable between all groups. Induction using ultrasonic nebulizers together with hypertonic saline was generally less well tolerated than compressed-air nebulizers and isotonic saline. We conclude that in normal subjects, although both nebulizers and saline types can induce sputum with reproducible cellular profile, ultrasonic nebulizers and hypertonic saline are more effective but less well tolerated.