Çipe, F.Arisoy, E.S.Correa, A.G.2024-05-192024-05-19202197830308069109783030806903https://doi.org/10.1007/978-3-030-80691-0_1https://hdl.handle.net/20.500.12713/4440The immune system exists to protect against the invasion of pathogens into the body. This function can only be achieved if the immune system can distinguish self from non-self, whether a microorganism, toxin, or allergenic substance. The immune system is vital in the response against severe, potentially fatal, infective episodes. In most cases, the immune system incapacitates the pathogen, and the individual recovers, but any defective immunological defense may give rise to primary immunodeficiency [1, 2]. Individuals with primary immunodeficiency are at risk of chronic or recurrent infection. Different categories of pathogens provoke different immune responses; therefore, an infection’s clinical features may provide clues about which aspect of the immunological response is deficient [1, 2]. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Switzerland AG 2022.eninfo:eu-repo/semantics/closedAccessBook Chapter3172-s2.0-8514117506810.1007/978-3-030-80691-0_1N/A