Does guanine concentration in house-dust samples reflect house-dust mite exposure?

Using specific ELISA extracts, we analyzed samples of pure mite cultures and house dust for group I allergens from Dermatophagoides pteronyssinus, D. farinae, and D. microceras. Correspondingly, we measured the concentration of guanine and xanthine by rigorous chemical methods. The pure mite cultures were used to correlate allergen levels with guanine levels. The house-dust samples one-sidedly contained more guanine than expected. This suggests that considerable amounts of guanine originate from non-house-dust mite sources and implies that guanine quantifications are of limited clinical value.