PATHOLOGY

Detailed explanation-1: -Generally, macrophages ingest and degrade dead cells, debris, tumor cells, and foreign materials. They promote homeostasis by responding to internal and external changes within the body, not only as phagocytes, but also through trophic, regulatory, and repair functions.

Detailed explanation-2: -The ability of lymphocytes to discriminate self and nonself is shaped within each individual by clonal deletion of T cells and B cells with high avidity receptors for self antigens present in primary lymphoid tissues (thymus and bone marrow, respectively).

Detailed explanation-3: -One type of white blood cell, the lymphocyte, is responsible for recognizing and reacting to non-self antigens.

Detailed explanation-4: -Macrophages recognize PAMPs via complementary pattern recognition receptors (PRRs). PRRs are molecules on macrophages and dendritic cells which are in contact with the external environment and can thus recognize PAMPs when present.