title: Modulation of T-helper cell populations: potential mechanisms of respiratory hypersensitivity and immune suppression.
abstract: Information presented at this symposium indicates that modulation of Th cell responses is one means by which xenobiotics may cause immunotoxicity. A shift from Th1 to Th2 responses can enhance both infectious and allergic disease. Hence, in some cases, a common mechanism may be responsible for effects that are generally considered to be very different. Because cytokines produced in the inflammatory process play a role in modulation of Th cell responses, there is a mechanism by which agents that appear to have only local effects at the portal of entry may, in fact, affect immune responses systemically. An understanding of conditions which trigger certain cytokine responses may be useful not only in understanding inflammation but also in predicting certain kinds of immunosuppressive and allergic responses. Future studies in this area are likely to provide insights into many areas of immunotoxicology.
authors.affiliation: National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA.
authors.forename: M K
authors.initials: MK
authors.lastname: Selgrade
authors.forename: D A
authors.initials: DA
authors.lastname: Lawrence
authors.forename: S E
authors.initials: SE
authors.lastname: Ullrich
authors.forename: M I
authors.initials: MI
authors.lastname: Gilmour
authors.forename: M R
authors.initials: MR
authors.lastname: Schuyler
authors.forename: I
authors.initials: I
authors.lastname: Kimber
mesh_terms: D000393:Air Pollutants / Q000009:adverse effects / Q000633:toxicity; D000818:Animals; D001249:Asthma / Q000209:etiology / Q000276:immunology / Q000473:pathology; D016535:Bronchial Hyperreactivity / Q000209:etiology* / Q000276:immunology; D003141:Communicable Diseases / Q000209:etiology / Q000276:immunology / Q000473:pathology; D016207:Cytokines / Q000096:biosynthesis; D004195:Disease Models, Animal; D006801:Humans; D006967:Hypersensitivity / Q000209:etiology / Q000276:immunology / Q000473:pathology; D007108:Immune Tolerance / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D008670:Metals / Q000009:adverse effects / Q000633:toxicity; D018417:Th1 Cells / Q000166:cytology* / Q000187:drug effects / Q000276:immunology / Q000528:radiation effects; D018418:Th2 Cells / Q000166:cytology* / Q000187:drug effects / Q000276:immunology / Q000528:radiation effects; D014466:Ultraviolet Rays / Q000009:adverse effects; D015262:Xenobiotics / Q000009:adverse effects / Q000633:toxicity*
chemical_list: D000393:Air Pollutants; D016207:Cytokines; D008670:Metals; D015262:Xenobiotics