Yes!!! You can be allergic to house dust and not dust mites. House dust is a mixture of many substances including shed human skin, mold, animal hair and dander, fibers, and dust mites and their excrement. The amount of each can vary from home to home. The significance of Late Phase skin test responses to an airborne allergen such as dust mites has long been controversial. Despite the lack of conclusive data, many allergists consider a delayed response to be significant. This is based on the known fact that the allergic response is made up of an early phase [immediate up to 30 minutes] followed by a more prolonged late phase reaction. The late phase typically occurs 4-8 hours after exposure but can occur even later in some circumstances. Based on this data it can be extrapolated that a delayed response up to 24 hours could be relevant.
Every allergist has their own style and protocol as to what they may remove from serum after a retest. Typically I do not remove an allergen that has shown significant reactivity on previous testing.
Finally, If you seem to be more clinically sensitive to dust…. it may be necessary for your allergist to review your allergy serum makeup and increase the individual components (such as dust mites, mold etc.) that you may have lost with the removal of house dust from your serum.