The science behind why mosquito bites itch involves a complex interaction between mosquito saliva and the human immune system. In this article, Doctronic explores the science behind mosquito bites and how to prevent them from ruining your summer. Key TakeawaysMosquito bites itch because the immune system releases histamine in response to proteins in mosquito saliva. The Role of Histamine in Immune ResponseWhen mosquito saliva enters the skin, immune cells called mast cells release histamine. This process evolved to alert the body to potential threats, but in the case of mosquito bites, it creates discomfort without providing real protection.