Immune system microorganisms role

Immune system—a collection of specific proteins, cells, and tissues that work to protect the body from foreign potentially harmful substances and microorganisms. The immune system plays a role in the control of lot of diseases, but also is the culprit behind the phenomena of allergies, hypersensitivity. There are some specific immune systems (see MALT, GALT, NALT, SALT). 

You H, Lee WJ, Lee WJ (2014) Homeostasis between gut-associated microorganisms and the immune system in Drosophila. Curr Opin Immunol 30 48-53. doi 10.1016/j.coi.2014.06.006 Zilber-Rosenberg I, Rosenberg E (2008) Role of microorganisms in the evolution of animals and plants the hologenome theory of evolution. FEMS Microbiol Rev 32(5) 723-735. doi FMR123 [pii] 10.1111/j.l574-6976.2008.00123.x... 

Hydrophilic surfactant proteins A (SP-A) and D (SP-D), secreted by type II pneumocytes, interact specifically with a wide range of microorganisms and play important roles in the innate, natural defense system of the lung [16]. Both mRNA and protein levels of SP-A and SP-D increase dramatically in response to lung infection, injury and endotoxin challenge [17]. Type II pneumocytes also express class II major histocompatibility complex (MHC) antigens and intracellular adhesion molecule (ICAM-1), which may facilitate pulmonary immune responses [15]. 

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