What Are Der p 1 and Der p 2?
Der p 1 (Dermatophagoides pteronyssinus allergen 1) and Der p 2 are the two major allergenic proteins produced by house dust mites—microscopic arachnids that live in virtually every home worldwide. These proteins are found primarily in dust mite fecal matter, which becomes the dried particles you inhale throughout your day.
House dust mites themselves are tiny creatures, invisible to the naked eye, that feed on the dead skin scales humans shed daily. A single gram of household dust can contain up to 19,000 mites. But here's what's truly problematic: it's not the mites themselves causing your allergies—it's their waste. Approximately 95% of dust mite allergens come from mite fecal particles that dry, break apart, and become airborne.
Der p 1 is a cysteine protease enzyme—meaning it doesn't just trigger allergic reactions, it actively breaks down the protective tight junctions between cells in your respiratory tract. This enzymatic activity allows allergens to penetrate deeper into your airways, facilitating allergic sensitization and inflammation. Think of Der p 1 as a protein that literally opens the door for allergens to invade your body more effectively.
Der p 2 is a non-proteolytic allergen that triggers immune responses through different mechanisms. It activates inflammatory pathways including NF-κB and MAPK, leading to the release of pro-inflammatory cytokines and the expression of adhesion molecules that recruit more inflammatory cells to your airways. Der p 2 essentially sounds the alarm that brings your immune system's inflammatory response rushing to the scene.
Both proteins, at approximately 7-14 nanometers in size, are small enough to remain suspended in the air for extended periods and penetrate deep into your respiratory system, reaching even the smallest airways in your lungs.

