title: Regulatory effects of IL-12 and IL-18 on Onchocerca volvulus- and Entamoeba histolytica-specific cellular reactivity and cytokine profiles.
abstract: In the present study, the cytokines interleukin (IL)-12 and IL-18 were evaluated for their capacity to modulate and to re-direct in vitro parasite antigen-specific cellular responsiveness in patients exposed to Onchocerca volvulus and Entamoeba histolytica infection. We found that IL-18 was highly capable of reducing parasite antigen-induced IL-10 production by PBMC. In contrast, addition or neutralization of IL-12, also in combination with IL-18 and the interferon-gamma-inducible chemokine IP-10 did not affect IL-10 production. Interestingly, the highest IL-10 levels were measured when IL-18 and IP-10 were both neutralized. Although having no effect on IL-10, IL-12 strongly promoted spontaneous and parasite antigen-driven IFN-gamma production by PBMC, whereas IL-18 was only moderately affecting IFN-gamma release by PBMC re-stimulated with E. histolytica- or O. volvulus-specific antigens. Both IL-12 and IL-18 diminished the cellular production of IL-13, and a synergistic effect was observed when the cytokines were combined. Likewise, neutralization of IL-12 enhanced Entamoeba and Onchocerca antigen-driven IL-13 production, but no further increase of IL-13 was observed, when anti-IL-12 and anti-IL-18 were used together. This study disclosed that IL-18 will significantly down-regulate parasite-specific IL-10 production, whereas IL-12 induced IFN-gamma and inhibited IL-13 production by PBMC from humans exposed to O. volvulus and E. histolytica. Such selective immune-regulatory capacity of IL-12 and IL-18 may comprise an important tool to re-direct polarized cytokine responses towards a balanced Th1/Th2 cytokine profile, which may prevent pathology and promote immunity against helminth and protozoan parasite infections.
mesh_terms: D000293:Adolescent; D000328:Adult; D000818:Animals; D000947:Antigens, Helminth / Q000276:immunology; D054357:Chemokine CXCL10; D019743:Chemokines, CXC / Q000096:biosynthesis / Q000276:immunology; D004748:Entamoeba histolytica / Q000276:immunology*; D004749:Entamoebiasis / Q000097:blood / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis / Q000276:immunology; D016753:Interleukin-10 / Q000096:biosynthesis / Q000276:immunology*; D020382:Interleukin-18 / Q000096:biosynthesis / Q000276:immunology*; D015848:Interleukin-5 / Q000096:biosynthesis / Q000276:immunology; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000378:metabolism; D008213:Lymphocyte Activation / Q000276:immunology; D008875:Middle Aged; D017181:Onchocerca volvulus / Q000276:immunology*; D009855:Onchocerciasis / Q000097:blood / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology; D018418:Th2 Cells / Q000276:immunology
chemical_list: D000947:Antigens, Helminth; D054357:Chemokine CXCL10; D019743:Chemokines, CXC; D020382:Interleukin-18; D015848:Interleukin-5; D016753:Interleukin-10; D007371:Interferon-gamma