cee_calendar_microbes微生物和過敏性疾病(文件)
【正文】 ferent forms of antigen presented to the GALT leads to systemic nonresponsiveness or immunity Antigen specific reduction in proliferative capacity Antigen specific clonal expansion 1st Ag challenge T cell proliferation and activation T cell proliferation and activation Subsequent challenges Profound reduction in proliferative capacity。 functional nonresponsiveness due to failure to clonally expand antigen specific clones and/or cell death Clonal expansion enhanced by each antigen challenge leads to productive immune response Soluble Ag Ag + adjuvant, microbes Allergic disease (Th2) Helminth Infection (Th2) Microbial Infection (Th1) The relationship between infection and allergic disease In developed countries: High incidence of allergic disease Low incidence of infectious diseases (Th1) Low infection with worms (helminths) In developing countries: Low incidence of allergic disease High incidence of infectious diseases (Th1) High infection with worms (helminths) Pathogens IL12, IL18 TH1 APC T TLRs Antigen presentation Costimulatory molecules IFNg Helminths, Allergens IL4, IL10 ? TH2 APC T TLRs Antigen presentation Costimulatory molecules IL4, IL,5 IL13 ? ? ? IFNg IL4 TLR signaling regulates the development of Th1 and Th2 cells The Hygiene Hypothesis Allergy and asthma have increased during the last 2050 years due to reduced exposure to childhood bacterial and viral infections brought about by improvements in vaccination and sanitation. In the absence of these Th1 polarizing stimuli mucosal immune responses fail to overe their inherent Th2 bias and bee slanted in the direction of allergy. Q u i ckT i me ? a n d aPh o t o J PE G d
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