IMMUNOLOGY

Detailed explanation-1: -Macrophages work as innate immune cells through phagocytosis and sterilization of foreign substances such as bacteria, and play a central role in defending the host from infection. However, residual macrophages in intestinal mucosa can potentially reduce inflammation to a greater extent than those in other tissues.

Detailed explanation-2: -Natural killer (NK) cells play a vital role in innate immune responses to infection; they express activation receptors that recognize virus-infected cells. Highly related to receptors recognizing tumor cells, the activation receptors trigger cytotoxicity and cytokine production.

Detailed explanation-3: -The innate immune responses are the first line of defense against invading pathogens. They are also required to initiate specific adaptive immune responses. Innate immune responses rely on the body’s ability to recognize conserved features of pathogens that are not present in the uninfected host.

Detailed explanation-4: -Macrophages are a type of white blood cell that play an integral part in the immune system with the role of phagocytosing foreign antigens, such as bacteria. They are able to present these antigens to other immune cells, such as T-cells, for further destruction.