Helminths 2

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Helminths preferentially induce Th2 responses

Th2 responses are protective against some g.i. nematodes

*helminth infection is often characterised by impaired T cell proliferation - mechanism allowing parasite survival while down-regulating pro -inflammatory responses

*T cell regulation (Treg) is associated with chronic infection

Main role is to suppress other cells (both Th1 and Th2)

depletion of Treg leads to muli-organ auto-immunity

Depletion of Treg reduces the recover of adult worms: suggesting that Treg interfere with effector T cell responses

Where helminths are endemic:

less Th1 = auto immunity

less Th2 = allergy associated diseases

increased incidence of allergy and auto-immune disease may be correlated with improvements in sanitation/hygiene and lack of exposure to infection

exposure to such infections in childhood establishes a regulatory network that helps prevent over-reaction

Key points:

achieving a balanced immune response is key to prevent pathology

in schistosome infection, Th2 responses are required, but have to be regulated

Helminth seems to protect against allergy and can modulate inflammatory disease