PATHOLOGY

Detailed explanation-1: -An antigen-presenting cell (APC) is an immune cell that detects, engulfs, and informs the adaptive immune response about an infection. When a pathogen is detected, these APCs will phagocytose the pathogen and digest it to form many different fragments of the antigen.

Detailed explanation-2: -A professional antigen presenting cell (APC) has the ability to capture and process foreign antigens, and to deliver the three signals for T cell activation (peptide MHC-TCR, costimulation and polarizing cytokines).

Detailed explanation-3: -Dendritic cells are the most important antigenpresenting cell of the three, with a central role in the initiation of adaptive immune responses (see Section 1-6).

Detailed explanation-4: -Antigen-presenting cells are vital for effective adaptive immune response, as the functioning of both cytotoxic and helper T cells is dependent on APCs. Antigen presentation allows for specificity of adaptive immunity and can contribute to immune responses against both intracellular and extracellular pathogens.