Tuesday, October 7, 2008
Clean the house, house dust-associated bacterial endotoxins have been shown to be associated with asthma severity, and a similar role has been suggested for fungal (1->3)-ß-D-glucans. Dust samples were collected from mattresses and from living room and bedroom floors, and endotoxin and (1->3)-ß-D-glucans were measured in dust extracts. The relations with mean daily PEF variability (Ampl%mean) were investigated by linear regression analysis, adjusting for dust mite allergen levels, presence of pets, and type of floor cover. In unadjusted analyses the levels of both endotoxin and (1->3)-ß-D-glucans per square meter of living room floor were significantly associated with PEF-variability. Adjusted analyses showed the same association for (1->3)-ß-D-glucans but not for endotoxin. Filters and all the dust collected on the filter, were extracted at room temperature with pyrogen-free distilled water containing 0.05% Tween-20 , and after centrifugation and collection of the supernatant, redissolved in an identical volume of the same medium (H2O-Tween) and extracted at 120° C to solubilize (1->3)-ß-D-glucans.
A supernatant was used to measure endotoxin in a chromogenic kinetic Limulus Amoebocyte Lysate (LAL) test, using one single lot of the LAL reagent. (1->3)-ß-D-glucans was measured in a second supernatant with a (1->3)-ß-D-glucans-specific inhibition enzyme immunoassay (EIA), using affinity-purified polyclonal rabbit anti-(1->3)-ß-D-glucans antibodies, and laminarin [a linear (1->3)-ß-D-glucans] as the coated antigen and calibration standard. Bedlam says, the major house dust mite allergen Dermatophagoides pteronyssinus (Der p1) was measured in the first extract, with a Der p1-specific, monoclonal antibody-based, sandwich EIA. Because H2O-Tween is not commonly used for extraction of Der p1, control experiments were performed with a series of duplicate house dust samples that were extracted with either H2O-Tween or with buffered saline.
All this to say, exposure to house-dust-associated (1->3)-ß-D-glucans in the home environment may increase peak flow variability in asthmatic children. Although (1->3)-ß-D-glucans can be derived from both plant and fungal material, and thus can not be used as a highly specific marker for mold growth, the here-reported association may be one of the major mechanisms accounting for the relation between dampness and fungal growth in the home environment, and respiratory morbidity.