Effects of gamma interferon on syntheses of DNA and proteins by Entamoeba histolytica.
To define the participation of cell-mediated immunity in resistance to amebic infection through the action of soluble mediators or lymphokines (LKs), including gamma interferon (IFN-gamma), we studied their effect on Entamoeba histolytica. Supernatants from cultures of lymphoid cells, which had been stimulated in vitro with concanavalin A and were rich in lymphokines (LRSNs), and recombinant IFN-gamma were used. LRSN and recombinant IFN-gamma inhibited the growth of E. histolytica trophozoites in vitro. These LKs did not show a cytotoxic effect on the ameba, but they did inhibit rather significantly protein and DNA syntheses of the protozoa. Interestingly, LRSN incubated at 4 degrees C in the presence of trophozoites lost the ability to inhibit the replication of vesicular stomatitis virus. IFN-gamma inactivated at pH 2 had no effect on DNA synthesis by the ameba, thus suggesting that IFN-gamma is responsible for the observed inhibition of parasite growth. Furthermore, the IFN-gamma inhibitory effect was abolished by a monoclonal antibody specific for this LK. The results suggest that IFN-gamma may participate in protection against amebiasis infection through the activity of mediators released by lymphocytes during infection.
Castellanos
C
C
Departamento de Immunología, Universidad Nacional Autónoma de México, Mexico City.
Ramos
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C
Ortiz-Ortiz
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L
D000042:Absorption; D000818:Animals; D000911:Antibodies, Monoclonal / Q000502:physiology; D000918:Antibody Specificity; D002474:Cell-Free System; D002478:Cells, Cultured; D004247:DNA / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D004748:Entamoeba histolytica / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007371:Interferon-gamma / Q000276:immunology / Q000494:pharmacology*; D008222:Lymphokines / Q000502:physiology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D011500:Protein Synthesis Inhibitors / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D011994:Recombinant Proteins; D013154:Spleen
D000911:Antibodies, Monoclonal; D008222:Lymphokines; D011500:Protein Synthesis Inhibitors; D011994:Recombinant Proteins; C021649:concanavalin A-induced helper factors; D007371:Interferon-gamma; D004247:DNA