The allergenicity of feather bedding material

Abstract

It has long been recognized that exposure to high levels of antigen is an important risk factor for the development and exacerbation of atopic asthma and other allergic disorders (1). For this reason allergen avoidance is advised for subjects with allergic disease and for children at risk of developing allergy (2). The principal indoor allergen is the house dust mite (3); several strategies have been suggested to reduce exposure to mite allergens in the bedroom, such as occlusive covers for mattresses, pillows and duvets (4).

Additionally, synthetic materials for pillows and duvets has been encouraged to avoid sensitization to feather allergens. However, a recent Finnish study has concluded that most positive skin test reactions seen with feather extracts are due to mite allergens (5). Feathers used for production of bedding material are extensively washed before use and feather bedding appears less allergenic than synthetic alternatives (6). This is partly due to the outer covering associated with the two types. Synthetic fillings have lighter thinner covering material. This facilitates the entry of house dust mites into the filling. Allergic symptoms to bedding are most probably related to Der p 1 sensitivity rather than the filling.

We investigated the prevalence of sensitivity to feather bedding material in a dust mite sensitive population. Their previous exposure to feather bedding material was assessed during interview and compared with observed sensitivity. 105 patients with confirmed dust mite (Der p 1) sensitivity and a symptomatic history to dust were included in the study. A further 25 nonatopic subjects were included as a control group.

Each subject was skin prick tested against dust mite, grasses, cat and commercial chicken feather extract (Bayer) and against extracts of duck feather, goose feather and polyester filling material. A positive response was considered as equal to or greater than a 3-mm wheal difference from the negative control.

Protein concentrations from the two feather extracts were extremely low at 9 µg/g feathers for goose and 18.5 µg/g feathers for duck. This illustrates the efficiency of the washing process used for preparation of the bedding material.

All atopic subjects responded to the Der p 1 and some to cat and/or grasses. There were no positive reactions to any of the feather or synthetic bedding extracts or the commercial chicken feather skin test reagent used, confirming the low prevalence of feather allergy demonstrated by other workers (5). None of the nonatopic controls reacted to any of the skin test solutions apart from the histamine control.

Of the atopic subjects only 15% were using feather filled bedding material and 25% indicated previous use such but had discontinued use of such products following concern over possible allergenicity. Contact with feather bedding material more than two years previously was considered as no contact. There was no association between skin test reactivity and current or previous use of feather bedding.

In conclusion, the feather fillings used in this study do not have the potential to sensitize individuals to feather allergens in normal usage.