Down-regulation of murine lymphocyte responsiveness to mitogens after treatment with antigens of Entamoeba histolytica.
Injection of mice with pathogenic Entamoeba histolytica (strain HM1-IMSS) antigens resulted in a decreased capacity of splenocytes to respond to mitogen-induced blastogenesis following a challenge with concanavalin A (Con A), phytohemagglutinin (PHA), and lipopolysaccharide (LPS), whereas no inhibition was observed in mice that had previously been injected with equivalent amounts of non-pathogenic E. histolytica-like Laredo antigens. Depletion of adherent cells in the splenocyte preparation indicated that these cells were not a major contributor to the observed immunosuppression. Quantification of splenic T-lymphocyte subsets demonstrated a significant decrease in Thy-1+ and Lyt-1+ cells, but Lyt-2+ cells were not affected. Splenocytes treated with pathogenic amoebic antigens in vitro affected the capacity of these cells to respond optimally to Con A- and LPS-induced blastogenesis but not to that induced by PHA. These findings demonstrate that amoebic antigens affect lymphocyte function and may be important co-factors in the immunoregulation and pathogenesis of amoebiasis.
Chadee
K
K
Institute of Parasitology of McGill University, Ste-Anne de Bellevue, Québec, Canada.
Denis
M
M
Keller
K
K
D000818:Animals; D000953:Antigens, Protozoan / Q000276:immunology*; D002478:Cells, Cultured; D003208:Concanavalin A / Q000276:immunology; D004748:Entamoeba histolytica / Q000276:immunology*; D005260:Female; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D010835:Phytohemagglutinins / Q000276:immunology; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
D000953:Antigens, Protozoan; D010835:Phytohemagglutinins; D003208:Concanavalin A