(1 -> 3)-beta-D-glucan and endotoxin in house dust and peak flow variability in children

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)-beta-D-glucans. In this study the relation between these agents and pe ak expiratory flow (PEF) variability was investigated in 148 children 7 to 11 yr of age of whom 50% had self- or parent-reported chronic respiratory s ymptoms. All children self-monitored twice daily their PEF for a period of 16 wk. Dust samples were collected from mattresses and from living room and bedroom floors, and endotoxin and (1-->3)-beta-D-glucan were measured in d ust extracts. The relations with mean daily PEF variability (Ampl%mean) wer e investigated by linear regression analysis, adjusting for dust mite aller gen levels, presence of pets, and type of floor cover. In unadjusted analys es the levels of both endotoxin and (1-->3)-beta-D-glucan per square meter of living room floor were significantly associated with PEF-variability (bu t not when expressed per gram of sampled dust), particularly in atopic chil dren with asthma symptoms. Adjusted analyses showed the same association fo r (1-->3)-beta-D-glucan but not for endotoxin. Although no associations wer e found with microbial agent levels in bedroom floor or mattress dust, high levels of (1-->3)-beta-D-glucan in living room floor dust apparently incre ase PEF variability in asthmatic children.