A subunit vaccine candidate region of the Entamoeba histolytica galactose-adherence lectin promotes interleukin-12 gene transcription and protein production in human macrophages.
The cysteine-rich region of the 170-kDa subunit galactose-adherence lectin (Gal-lectin) of Entamoeba histolytica is a subunit vaccine candidate and a protective antigen in the gerbil model of amebiasis. Macrophage-mediated immunity is important for protection against E. histolytica and is activated by Th1 cytokines. As Th1 differentiation is promoted by IL-12, we investigated what portion of the Gal-lectin could stimulate IL-12 in human THP-1 macrophages. Native Gal-lactin stimulated IL-12 p40 / p35 mRNA expression in a dose- and time-dependent manner as measured by reverse transcriptase-PCR. Human immune serum and Gal-lectin mAb inhibition studies identified amino acids (aa) 596 - 998 as immunogenic and containing the IL-12 inducing domain. IFN-gamma priming augmented Gal-lectin-induced IL-12 mRNA expression independent of TNF-alpha and IL-1beta, and was required for IL-12 p70 protein production from macrophages and human peripheral blood mononuclear cells. Gal-lectin plus IFN-gamma stimulated IL-12 p40 and p35 gene transcription with stable mRNA transcripts and a differential requirement for protein synthesis. These results suggest that aa 596 - 998 of the Gal-lectin can confer Th1-mediated protection against amebiasis through IL-12 induction.
Campbell
D
D
Institute of Parasitology, Macdonald Campus of McGill University, Ste. Anne de Bellevue, Québec, Canada.
Mann
B J
BJ
Chadee
K
K
D000818:Animals; D000954:Antigens, Surface / Q000235:genetics / Q000276:immunology; D004748:Entamoeba histolytica / Q000276:immunology*; D005786:Gene Expression Regulation / Q000276:immunology*; D006801:Humans; D018664:Interleukin-12 / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D037102:Lectins; D008264:Macrophages / Q000276:immunology*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology*; D015800:Protozoan Proteins / Q000235:genetics / Q000276:immunology*; D016052:Protozoan Vaccines / Q000276:immunology*
D000954:Antigens, Surface; D037102:Lectins; D008562:Membrane Glycoproteins; D015800:Protozoan Proteins; D016052:Protozoan Vaccines; C052452:galactose inhibitable adherence protein, Entamoeba histolytica; D018664:Interleukin-12