It opens to the infinite world of smells, whether for better or for worse. It has the gift of stimulating sexual desire, by capturing pheromones. It gives us permanent access to breathing and even serves as a filter of ambient air by damming dust, pollen or any other element that threatens to irritate us. And far from remaining marble against the invaders, the nose - it is obviously him that it is - vigorously defends any disruptive intrusion. For proof, sneezing untimely that violently expel the most adventurous intruders or the saliva-forming hairs that line the nasal mucosa, real dust traps.
But against viruses, these mechanical traps prove to be powerless. Result: these invade our upper respiratory tract and rush shamelessly into the heart of our lungs. We fall ill, from a cold for example. He, so anxious to protect us from all kinds of enemies, seems strangely ineffective against microbes.
It's actually the opposite! Against all odds, the nose hides a formidable weapon against viruses. Its mucous membranes, in addition to protecting us from dust, harbor small sentinels that ensure the identification of harmful pathogens and, if necessary, neutralize them. And these babysitters seem endowed with a long-term memory. When the flu hits us the first time, it will lose the battle during an upcoming invasion, our nose has meanwhile transformed into an unsuspected antiviral fortress. If the smell of a madeleine can reactivate distant memories, an inhaled virus revives, for its part, these protective entities, called "resident memory cells".
The memory of white blood cells
It took the intuition of a team of biologists from the Department of Microbiology and Immunology at the University of Melbourne (Australia) to flush out these sentinels: white blood cells called cytotoxic T lymphocytes - or T CD8. Far from circulating throughout the body, these immune cells reserve their protection in highly targeted areas. Capable of destroying cells infected with viruses and bacteria, they activate themselves in a given tissue so as not to leave it and defend against pathogens














