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S Chugh

Publications and source records attributed to S Chugh.

28 records · Page 2Linked to original sources
PubMed1986

Antibody-dependent macrophage-mediated cytotoxicity against Entamoeba histolytica.

Interactions between trophozoites of Entamoeba histolytica and peritoneal exudate macrophages from unsensitised and antigen-sensitised animals were studied in vitro. Normal macrophages killed trophozoites to some extent. This killing capacity was enhanced by prior sensitisation of the animals with specific antigen. Incorporation of anti-amoebic antiserum in the amoeba-macrophage mixture greatly enhanced the killing capacity of macrophages. Fraction one (F-I) of a crude amoebic extract was most effective in enhancing the cytotoxicity of macrophages by prior sensitisation and anti-F-I serum was the most effective antiserum. The cytotoxicity-inducing capacity of the immune serum resided in the IgG but not in the IgM fraction.

Animals↗
PubMed1986

Elucidation of cellular population and nature of anti-amoebic antibodies in cytotoxicity to Entamoeba histolytica (NIH:200).

Interactions between trophozoites of Entamoeba histolytica and cells of the immune system were studied in vitro by mixing effector cells obtained from normal and immunized guinea pigs with trophozoites in a ratio of 10:1. Crude amoebic extract (CAE) and its highest molecular weight (MW 650,000) fraction (F-I) were used for priming the effector cells in vivo. The effector cells were collected from the spleens of normal and immunized animals. Lymphocytes were prepared by allowing splenic mononuclear cells to adhere to plastic, followed by passage through nylon wool column. There was no significant difference between the killing capacity of mononuclear cells, monocyte depleted mononuclear cells or nylon wool fractionated lymphocytes, indicating that probably monocytes and B-cells were not involved in the cytotoxicity against E. histolytica. The data suggest that effector cells probably belonged to the T-cytotoxic and K-cell category. Both CAE and F-I sensitization could induce cytotoxicity of lymphocytes against trophozoites. Similarly, anti-CAE and anti-F-I sera were found to enhance the killing capacity of effector cells in vitro. The ability of anti-amoebic serum to induce cytotoxicity was found to be independent of complement involvement and resided in IgG but not in IgM.

Animals↗
PubMed1985

Interactions between trophozoites of Entamoeba histolytica and cells of the immune system.

The interaction between Entamoeba histolytica trophozoites and cells of the immune system was studied in vitro. Both immune as well as non-immune mononuclear cells (MNC) to some extent were capable of exerting a cytotoxic effect on E. histolytica trophozoites. Incorporation of immune serum directed against the trophozoites in the reaction mixture resulted in a marked increase in the killing capacity of MNC. Highest killing was observed (96.7 +/- 1.04%) with MNC obtained from animals immunized with fraction-I(F-I) of the crude amoebic extract in association with anti-F-I serum. This cytotoxic event was found to be independent of complement involvement and required very low antibody concentrations. This antibody-dependent cellular cytotoxicity against E. histolytica in vitro was found to correlate well with the results of experiments reported earlier by us and others where a high degree of protection has been shown after vaccination of animals with F-I followed by challenge with highly virulent strains of E. histolytica.

Animals↗
PubMed1981

Virulence of Entamoeba histolytica in rat and its comparison with the serological responses of the amoebic patients.

The virulence of 70 isolates of Entamoeba histolytica was studied in the Wistar strain of albino rat by intracaecal inoculation of amoebae. The results were evaluated by the Neal scoring system, histopathological grading of ulcers and virulence indices. It was found that isolates from acute amoebic cases could infect and produce ulcers in significantly more animals than could the isolates from asymptomatic cyst passers. The virulence indices of isolates from acute cases were also significantly higher as compared to those from asymptomatic cyst passers. However, there was no significant difference between virulence indices of isolates from acute cases and non-dysenteric amoebic colitis. This study also showed that Neal scores failed to correlate with the type of pathology produced by the amoebae in the caecum. It is felt that virulence indices which depend upon the histopathological lesions should also be taken into consideration. The serological response of the patients tended to correlate with the virulence indices of isolates but only minimally. The results thus contradict a common belief amongst clinicians that higher levels of anti-amoebic antibodies reflect severe disease, as compared to low levels of antiamoebic antibodies.

Acute Disease↗