So one very common allergic reaction is hay fever, which is the way our immune system actually responds to grass pollen. When the allergic individual inhales pollen, that pollen, which is essentially a microscopic particle, can begin to release antigens that our body sees as pathogenic. So let's take a look at the following diagram to illustrate how our mechanism is actually carried out. So, let's suppose this is the air pathogeway, the bronchiol of our lungs. These are the epithelial cells, as shown, and these are the microscopic pollen particles. Now, as the pollen particle moves, it can release these tiny particles, even smaller particles that our body labels as pathogenic.