PATHOLOGY

Detailed explanation-1: -Professional antigen presenting cells (APCs) are immune cells that specialize in presenting an antigen to a T-cell. The main types of professional APCs are dendritic cells (DC), macrophages, and B cells.

Detailed explanation-2: -T Helper (Th) Lymphocytes T helper cells recognize viral peptides in association with class II MHC protein, usually on the surface of an antigen-presenting cell (APC).

Detailed explanation-3: -Human T cells express major histocompatibility complex (MHC) class II antigens and adhesion molecules characteristic of antigen-presenting cells (APCs), and recent in vitro and in vivo evidence supports an antigen-presenting function for T cells.

Detailed explanation-4: -Helper T cells themselves, however, can only function when activated to become effector cells. They are activated on the surface of antigen-presenting cells, which mature during the innate immune responses triggered by an infection.