title: Trypanosoma cruzi-induced decrease in the level of interferon-gamma receptor expression by resting and activated human blood lymphocytes.
abstract: A substantial proportion of human peripheral blood mononuclear cells (PBMC) manifested a decreased capacity to express membrane interferon-gamma receptors (IFN-gamma R) when co-cultured with Trypanosoma cruzi. Among the lymphocytes, B cells accounted for the bulk of this effect, evidenced by a marked drop in the proportion of CD19+ or CD20+ cells expressing IFN-gamma R. Decreased IFN-gamma R expression by B lymphocytes was seen as early as 3 h after co-culture with T. cruzi and persisted for at least 24 h. The parasite had no detectable effect on CD19, CD20 or DR antigen expression by B lymphocytes. Neither the proportion of B cells expressing these markers nor the membrane density of these molecules varied significantly in the presence of T. cruzi. In PBMC cultures stimulated with Staphlyococcus aureus Cowan I (SACI), T. cruzi decreased the percentages of both IFN-gamma R+ and IFN-R+bright (cells expressing above-normal levels of surface IFN-gamma R) B lymphocytes. Cell-free filtrates of T. cruzi suspensions reproduced the suppressive effects of living parasites on IFN-gamma R expression by B cells. When T. cruzi present, the intracellular levels of IFN-gamma R molecules in resting or SACI-activated B lymphocytes, represented by fluorescence intensity, were well below control values, suggesting that decreased surface expression resulted from suppressed IFN-gamma R synthesis. Among T (CD3+) cells, 10.8% to 39.6% (7 donors) expressed surface IFN-gamma R and did so at a very low level. These percentages were also reduced by T. cruzi.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Microbiology, Michigan State University, East Lansing 44824, USA.
authors.forename: F
authors.initials: F
authors.lastname: Kierszenbaum
authors.forename: H
authors.initials: H
authors.lastname: Mejia Lopez
authors.forename: M K
authors.initials: MK
authors.lastname: Tanner
authors.forename: M B
authors.initials: MB
authors.lastname: Sztein
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000032:analysis; D001402:B-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002478:Cells, Cultured; D014355:Chagas Disease / Q000276:immunology; D015536:Down-Regulation / Q000276:immunology; D005434:Flow Cytometry; D006684:HLA-DR Antigens / Q000032:analysis; D006801:Humans; D008213:Lymphocyte Activation; D051379:Mice; D008813:Mice, Inbred ICR; D015800:Protozoan Proteins / Q000494:pharmacology; D017471:Receptors, Interferon / Q000378:metabolism*; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D014349:Trypanosoma cruzi / Q000276:immunology*; D000096743:Interferon gamma Receptor
chemical_list: D015703:Antigens, CD; D006684:HLA-DR Antigens; D015800:Protozoan Proteins; D017471:Receptors, Interferon; D000096743:Interferon gamma Receptor