Recovery from Infection

This chapter discusses the immunological factors associated in the recovery of host from infections. Antibody, T cells, natural killer cells, complement, phagocytes, and interferon are involved in the response to nearly all infections and, without any doubt, are together responsible for recovery. There is good evidence that T-cell-mediated immunity is of supreme importance in recovery from a variety of microbial infections. These are the infections in which the microorganism replicates intracellularly. Tissue responses in the host bear the hallmarks of T-cell involvement, the infiltrating cells consisting primarily of lymphocytes and macrophages. Inflammation, whether induced by immunological reactions, tissue damage or microbial products, plays a vital role in recovery from infection. Inflammation is necessary for the proper functioning of the immune defenses because it focuses all circulating antimicrobial factors onto the site of infection. Complement can carry out antimicrobial activities. However, there is little direct evidence that the antimicrobial activities of complement are in fact important in the body. Interferons also act on uninfected cells, binding to a cell surface receptor and activating a number of genes involved in immunity to viruses. Multimechanistic recovery is illustrated in the chapter and other issues, such as the role of temperature, tissue repair, and resistance to re-infection are discussed.