Introduction
The immune system is commonly conceived as the set of cells and molecules which participate in a concerted and tuned
The immune system is commonly conceived as the set of cells and molecules which participate in a concerted and tuned

Innat immunity Innate (also referred to as natural or native) immunity operates in the early stage of the immune response

Humoral adaptive immune responses Humoral and cellular (or cell-mediated) adaptive responses are described by the different components involved in the

Cellular immunity is mediated by T lymphocytes (T cells). Intracellular microbes (eg. viruses) which are able to survive and proliferate

Although innate immunity reactions involve effective mechanisms able to control and even eradicate threats such as infections (not discussed in
As mentioned above, T-cell’s functions are dependent on their physical interaction with other cells: they need to recognize antigens associated

TH cell activation and licensing The first event in helper T-cell activation involves DC-mediated antigen recognition (with or without B7),
The scope of this chapter was to present the main aspects of the immune response. They are summarized as follows :
Carlo Pifferi Carlo Pifferi obtained his Master’s degree in Pharmaceutical Chemistry and Technology, under the supervision of Prof. C. Nativi,