Handbook of Immunological Properties of Engineered Nanomaterials

Abstract

The immuno system functions to defend the host from pathogenic microorganisms, such as bacteria, viruses, fungi, and other invaders. This defensive function is performed by leukocytes and many other specializes cells distributed in different organs, specially in the lymphoid and haemopoietic systems. However, the different cells interact each with other giving an immunologic reply coordinated and direct to eliminate the pathogenic microorganism or to minimize the produced damages. The immune system is highly versatile to recognize and destroy foreign elements, building a multistage response against them. It includes a large variety of cells and many types of soluble elements. Non-specific immune cells, such as macrophages, granulocytes, dendritic, or natural killer cells, together with specific cells (T helper, T regulatory, B lymphocytes, etc) are the most important cellular components. The  cooperation between non-specific cells with specific ones (B and T lymphocytes) and the secretion of soluble factors are crucial for a good adaptive immune response. Antigenicity is a subtype of the immunogenicity response characterized by the formation of an antibody specific to the given type of foreign substance (i.e. Nanoparticles and therapeutic proteins), called antigen. Thus, although the main purpose of the immune system is the recognition of pathogens, it is possible to develop immune responses against non-pathogens or foreign elements. This the reason why some people develop quite strong immune responses to certain components.  These responses are called allergy or hypersensitivity reactions, which include exaggerated humoral or cellmediated responses to non-pathogen components. However, despite many years of intensive studies, it is still not known why a particular person develops an allergy and others do not.