Allergen Der p1 and guanine production of house dust mites Dermatophagoides pteronyssinus in a semi-natural environment

Hygienic limits for mite allergen exposure are established on empirical grounds. The correlation of mite numbers, guanine content and allergen Der p 1 or group 1 content in house dust is sometimes obscure. The aim of this study is to determine the ratio of newly produced allergen Der p 1 and guanine per mite per day in a controlled environment. In a semi-natural test system, house dust mites (D. pteronyssinus) were incubated on soiled carpets at 75% and 80% relative humidity (rH) for 2,4, 6, and 8 weeks. Guanine and Der p 1 production per mite per day was calculated by determination of the guanine and allergen Der p 1 content of the mite substrates, and integration of the counted number of live mites per incubation period. At 75% rH, mean Der p 1 production per mite per day was 0.5 ± 0.1 ng. Guanine production amounted to 15 ± 4 ng per mite per day. The allergen production was lower than expected from literature data, which may be related with a different diet. The ratio between the geometric means of Der p 1 and guanine in these experiments is 1:50 on the average. This is remarkably lower than the ratio between the internationally accepted hygienic limits in house dust for these compounds (1:300). Increasing humidity to 80% rH did not result in significant production changes. Differences in production and degradation of allergens and guanine, under different indoor conditions will account for the deviation in their mutual correlations, thus influencing the usefulness of these parameters in exposure assessments and decreasing the validity of generalized hygienic limits in individual cases.