Innate immunity prevents tissue invasion by Entamoeba histolytica.

Although innate and adaptive immunity both play a role in amoebiasis, the mechanisms involved in the elimination of Entamoeba histolytica are poorly understood. To provide more information about the innate immune mechanisms that may confer protection against invasive amoebiasis, we administered inflammatory substances (bacillus Calmette-Guérin, lipopolysaccharide, complete Freund's adjuvant, or mineral oil) into the peritoneum of hamsters. The animals were then challenged with pathogenic trophozoites of E. histolytica and, after 7 days, the protective host response was analysed. We found that the nonspecific inflammatory response induced in the peritoneum was sufficient to prevent liver invasion by E. histolytica. In vitro experiments showed that the killing of trophozoites was mediated by peritoneal macrophages and a protein of 68 kDa with peroxidase activity.

Activity of a crude extract formulation in experimental hepatic amoebiasis and in immunomodulation studies.

The activity of a crude extract formulation was evaluated in experimental amoebic liver abscess in golden hamsters and in immunomodulation studies. The formulation comprises the following five plants-Boerhavia diffusa, Tinospora cordifolia, Berberis aristata, Terminalia chebula and Zingiber officinale. The formulation had a maximum cure rate of 73% at a dose of 800 mg/kg/day in hepatic amoebiasis reducing the average degree of infection (ADI) to 1.3 as compared to 4.2 for sham-treated controls. In immunomodulation studies humoral immunity was enhanced as evidenced by the haemagglutination titre. The T-cell counts remained unaffected in the animals treated with the formulation but cell-mediated immune response was stimulated as observed in the leukocyte migration inhibition (LMI) tests.

Dot-enzyme-linked immunosorbent assay (Dot-ELISA) of anti-Entamoeba histolytica antibodies in human serum and colostrum.

Seroepidemiologic and clinical studies of amoebiasis require improved methods for the detection and titration of anti-Entamoeba histolytica (Eh) trophozoite antibodies. We have developed a Dot-enzyme-linked immunosorbent assay (Dot-ELISA) to titrate anti-Eh antibodies in human serum and colostrum. The anti-Eh serum IgG antibody titers from healthy individuals and from patients with amoebic liver abscess obtained, with our Dot-ELISA were similar to those obtained with a standard ELISA, but the background values were lower. Significant anti-Eh sIgA antibody titers were found in seven out of 42 colostrum samples of mothers of newborn children with diarrhea. Our Dot-ELISA is rapid, inexpensive, and might be used for the diagnosis of individuals and in seroepidemiologic studies of amoebiasis.

Identification of Entamoeba histolytica antigens recognized by IgA class human antibodies in sera and colostra of puerperal women using immunoblotting techniques.

Immunodetection of total antigens of Entamoeba histolytica trophozoites transferred to nitrocellulose paper was realized with IgA antibodies present in colostra and sera samples of 28 puerperal women and in 24 sera samples of patients with a diagnosis of amebic hepatic abscess. The most frequently recognized antigens by colostra antibodies were those which correspond to 1290, 82.79, 52.14, 40.91, 37.75, 35.08, 33.52, 28.53, 27.53 and 25.32 KDa of molecular weight, in the case of puerperal sera those of 82.79, 52.14, 40.91, 37.75, 35.08, 33.52, 28.53, 27.53, and 25.32 KDa, whereas the sera of patients with amebic hepatic abscess those of molecular weight of 719, 118.45, 88.45, 69.45, 55.26, 52.14, 49.38, 42.72, 36.81, 35.08, 33.52, 25.32, 23.82, 23.47, 20.52 and 20.03 KDa. The putative adhesins were recognized infrequently by Iga of puerperal colostra and sera while the IgA of sera of patients with amebic hepatic abscess recognized those of 118.45 KDa (112 KDa in other studies) in 83.33% of the cases.