What is the immune response to Entamoeba histolytica in the pathogenesis of amebiasis?

Updated: Jul 19, 2019
  • Author: Vinod K Dhawan, MD, FACP, FRCPC, FIDSA; Chief Editor: Michael Stuart Bronze, MD  more...
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Serum antibodies in patients with amebic liver abscess develop in 7 days and persist for as long as 10 years. A mucosal IgA response to E histolytica occurs during invasive amebiasis; however, no evidence suggests that invasive amebiasis is increased in incidence or severity in patients with IgA deficiency.

Cell-mediated immunity is important in limiting the disease and preventing recurrences. Antigen-specific blastogenic responses occur, leading to production of lymphokines, including interferon-delta, which activates the killing of E histolytica trophozoites by the macrophages. This killing depends on contact, oxidative pathways, nonoxidative pathways, and nitric oxide (NO).

Lymphokines, such as TNF-α, are capable of activating the amebicidal activity of neutrophils. Incubation of CD8+ lymphocytes with E histolytica antigens in vitro elicits cytotoxic T-cell activity against the trophozoites. During acute invasive amebiasis, T-cell response to E histolytica antigens is depressed by a parasite-induced serum factor.

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