Immunological Memory and Infection

Abstract

This chapter focuses on the principles of immune memory. It is divided into four parts: (i) a historical perspective of vaccination, (ii) an overview of protective immunity to microbes, (iii) a discussion of the current models of memory T- and B-cell differentiation, and (iv) an overview of the mechanisms involved in maintaining immunological memory. Microbial infections usually induce both T- and B-cell long-term memory. The kinetics and anatomic location of antibody production after an acute viral infection are shown. In summary, immunological memory in the B-cell compartment consists of memory B cells and plasma cells: two distinct cell types with different anatomic locations and very different functions. The rapid rise in antibody levels on reinfection is the result of memory B-cell differentiation into new antibody-secreting plasma cells. Since preexisting antibody provides the first line of defense against infection by microbial pathogens, the importance of plasma cells in protective immunity cannot be overstated. In fact, it could be argued that plasma cells may be the single most important cell type in protective immunity to infections. In conclusion, in this chapter an attempt has been made to give an overview of the principles of immunological memory to infection. This remains one of the most exciting areas of immunology and infectious diseases, and there are many challenges ahead.