Bacterial Toxins Are Successful Immunotherapeutic Adjuvants and Immunotoxins

Bacterial protein toxins of pathogenic bacteria play an important role in infectious diseases to hijack mammalian cells and manipulate host immune responses. Several bacterial toxins and their non-toxic mutants have been intensively studied over the past decades in order to harness their abilities to enter host cells for stimulation of adaptive T cell responses, direct elimination of cancer cells or to boost immunity as adjuvants. Moreover, another set of bacterial toxins called effectors, which are translocated into the host cells by specialized secretion systems, have been used to facilitate the delivery of heterologous antigens into antigen presenting cells. Some of the most powerful bacterial neurotoxins have found their application in treatment of various neurological disorders as well as in cosmetic industry. Whereas few bacterial toxins are currently in various phases of clinical cancer trials, the immunotherapeutic potential of others needs to be established further. This chapter will introduce bacterial toxins used in immunotherapy and present the major achievements in this field. Similarly, the hurdles and limitations of the use of bacterial toxins in human immunotherapy will be discussed together with other diagnostics applications.