Serum from Entamoeba histolytica-infected gerbils selectively suppresses T cell proliferation by inhibiting interleukin-2 production.
Suppression of T and B cell responses during invasive amebiasis may be serum mediated. The mechanism of serum-mediated suppression of spleen cell lymphoproliferation from gerbils with amebic liver abscess was examined. Compared with uninfected gerbil serum (10%), serum samples collected at days 10, 30, and 60, but not at day 20 after infection, augmented both concanavalin A (Con A; T cell mitogen)- and lipopolysaccharide (LPS; B cell mitogen)-induced proliferation of homologous spleen cells. Only day 20 serum (>5%) inhibited Con A- but not LPS-induced proliferation of spleen cells from uninfected gerbils. The suppressive mechanism was independent of nitric oxide and prostaglandin but involved reduced interleukin (IL)-2 production. Addition of exogenous IL-2 reversed the suppressive effect of day 20 serum on Con A-stimulated proliferation. These results identify a mechanism whereby serum may contribute to transient suppression of T cell responses during Entamoeba histolytica infections.
Campbell
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Department of Immunology, University of Manitoba, Winnipeg, Manitoba R3E 0W3, Canada. DarrenC_UofM@yahoo.com
Gaucher
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Chadee
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D000818:Animals; D003208:Concanavalin A / Q000494:pharmacology; D005849:Gerbillinae; D007108:Immune Tolerance; D007376:Interleukin-2 / Q000096:biosynthesis* / Q000494:pharmacology; D008101:Liver Abscess, Amebic / Q000097:blood* / Q000276:immunology*; D008213:Lymphocyte Activation; D013154:Spleen / Q000166:cytology / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
D007376:Interleukin-2; D003208:Concanavalin A