Improvement of the slide hemagglutination test for rapid Chagas' disease screening in epidemiological surveys

A slide hemagglutination test, here called SHAT, which is practical and economical for seroepidemiological surveys was standardized. This is an improved modification of the rapid hemagglutination test (RHA) which utilizes a short-lived reagent prepared with fresh blood cells. The reagent and conditions of the test were considerably modified and, most importantly, an alkaline-solubilized Trypanosoma cruzi epimastigote antigen reagent is proposed. The stability of the SHAT reagent was at least one year at 4 degrees Celsius, in an appropriate liquid suspension. The SHAT was applied to 71 serum samples from patients with Chagas' disease and from 235 clinically healthy blood donors. Sensitivity, specificity and positive and negative predictive values for the selected cutoff titer corresponding to 1:4 dilution were 0.972 (0.903-0.992)9 O.983 (O.957-0.993) 0.945 (O.867-0.979) and O.991 (O.969-0.998), respectively. These values were comparable to those found for the RHA, immunofluorescence (IFT), indirect hemagglutination (IHAT) and complement fixation (CFT) tests. These data suggest that the SHAT should be useful for seroepidemiological surveys conducted at public health laboratories in developing countries.

Mononuclear cell cytotoxicity in rats with Walker 256 tumor

In the present study we characterized the cytotoxicity of Wistar rat mononuclear cells from 21 animals which received 10(6) Walker 256 tumor cells by the subcutaneous route. All animals developed the tumor. Cytotoxicity was studied 15 days after inoculation using spleen, thymus and lymph node T lymphocytes as well as macrophages from the peritoneal cavity. A Walker 256 tumor cell suspension and tumor cells in culture (YAC-1) were labelled with 51Cr and used as target cells, according to the Herberman technique and a gamma counter was used for counting. Anti-Walker cell cytotoxicity was significantly decreased in T lymphocytes from the spleen (9.6 vs 51.1 for the control) and thymus (11.5 vs 38.2 for the control), whereas no difference was observed for lymph nodes (41.2 vs 49.5 for the control) or macrophages (43.4 vs 46.3 for the control). Anti-YAC-1 cytotoxicity was significantly decreased in T lymphocytes from all lymphoid organs compared to control: 23.6 vs 42.8 for the spleen, 22.6 vs 41.1 for the thymus, 26.6 vs 42.1 for lymph nodes, and 27.1 vs 46.3 for macrophages. No correlation was observed between tumor weight, and anti-Walker cytotoxicity or anti-YAC-1 cytotoxicity.