Who are our Old Friends?
Rook hypothesizes that the immune system has evolved to require input from at least three sources collectively called the Old Friends:
Commensal microbiota:
diverse range of species found on normal skin, gut, airways, urogenitary tract, etc
Transmitted by mothers and other family members
Environmental microbiota:
diverse range of species found on animals, soil, air, plants
Spp. which inhabit our indoor and outdoor environments
Old Infections:
Helminths Salmonella, HAV, H. Pylori etc
Cause chronic infections – have to be tolerated, attempts to eliminate cause tissue-damage
