how does antigen processing work? and how was this micrograph taken?

Question

anonymous · Answer

I'm not sure what micrograph you're talking about, but antigen processing works in one out of two ways - either the cell, ie a macrophage, absorbs a foreign substance from its surroundings and breaks it down in lysosomes inside the cell, whereafter it presents parts of the foreign substance in the form of peptides on its exterior on an MHC class II molecule, that is specific to specialized antigen presenting cells, such as macrophages and dendritic cells, so that lymphocytes may be activated to better the defense against the specific antigen. Or a normal cell, ie an epithelial cell, is infected by a virus or such, in which case pieces of the viral protein products will be presented on the cell on an MHC class I molecule that is present in all cells, and are specialized in presented antigens, that are derived from an infection present inside the cell, to the cells of the immune system.