IMMUNOLOGY

Detailed explanation-1: -An APC, such as a macrophage, engulfs and digests a foreign bacterium. An antigen from the bacterium is presented on the cell surface in conjunction with an MHC II molecule Lymphocytes of the adaptive immune response interact with antigen-embedded MHC II molecules to mature into functional immune cells.

Detailed explanation-2: -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-3: -Although dendritic cells are important in presenting antigen, particularly to initiate primary immune responses, macrophages are the professional APC type most prominent in inflammatory sites and specialized for clearing necrotic and apoptotic material.

Detailed explanation-4: -Professional APCs include dendritic cells, macrophages, and B cells, whereas nonprofessional APCs that function in antigen presentation for only brief periods include thymic epithelial cells and vascular endothelial cells.

Detailed explanation-5: -All professional APCs also express MHC class I molecules as well. The main types of professional antigen-presenting cells are dendritic cells, macrophages and B cells.