Antigens: substances that can mobilize adaptive defenses and provoke immune response
-Characteristics: complete or hapten antigen, contains antigentic determinants, self-antigen
A self-antigen is covered by a variety of proteins and can be antigenic to other cells
a group of self-proteins are Major Histocompatibility Complex (MHC) and allow T lymphocytes to recognize
Antibodies: also recognized as Immunoglobulins, proteins secreted by plasma cells
^capable to bind to specific antigen detected by B cell
Structure: T or Y shape with two heavy chains and two light chains
Have 5 classes:
lgM: secreted by plasma cell during primary response, activated complement, many antigen-binding sites
lgA: found in body secretions such as sweat, saliva, intestinal juice, stops pathogens from attacking epithelial cell surface
lgD: found on B cell surface, function as B cell anitgen-receptor
lgG: abundant (75-85%), main for primary&secondary response, activates complement, protects from bacteria/virus/toxins
lgE: stem ends bind to mast cells or basophils, triggers release of histamine or inflammatory response, secreted by plasma cells in skin, only found in plasma