Evaluation of sarcoma 180 (ascitic tumor) in mice infected with Schistosoma mansoni

Camundongos infectados com 60 cercárias de Schistosoma mansoni tornaram-se mais resistentes ao sarcoma 180 na forma de tumor ascítico. A inoculaçäo das células tumorais foi feita no 50§ dia de infecçäo e a evoluçäo do tumor foi acompanhada através da pesagem dos animais com intervalos de 48 horas. Nos camundongos infectados o ganho de peso (formaçäo da ascite) começou mais tarde e foi menor do que nos controles näo infectados. Também o número de células tumorais na cavidade peritoneal 72 horas após a implantaçäo do tumor foi menor no grupo infectado. Este aumento de resistência a um tumor transplantável possivelmente está relacionado ao efeito de endotoxinas sobre a atividade de tumoricida dos macrofagos ativados pela infecçäo. A imunossupressäo induzida pela infecçäo favorece a proliferaçäo de bactéria da flora endógena aumentando a quantidade de endotoxinas absorvidas pelo intestino

Surface Properties of Cell Membrane Tested by Lectin Induced Cytoagglutination (I)

This report describes surface properties of several cell membranes tested by lectininduced agglutination reactions which were quantitated using the microquantitative particle counter agglutination assay of Davis et al. (1976). The quantitative assays of concanavaalin A (con A) induced agglutination were performed for rabbit erythrocyte, rat erythrocyte, human erythrocyte, and sarcoma 180 mouse ascites cells. The percent agglutination versus the con A concentration revealed a sigmoid curve in all cases, but the steepness of the sigmoid curve is variable depending on the cell types. It varies even with the same cell but in different species. Optimum cell concentration was (0.92-0.95) x 10(7) cells/ml final concentration in the hanging drop, for rabbit erythrocytes, (0.77-1.64) x 10(7) cells/ml for rat erythrocytes, (1.59-2.7) x 10(7) cells/ml for human erythrocytes and (0.23-0.39) x 10(7) cells/ml for sarcoma 180 mouse ascites cells. When minimal and maximal agglutination percentages were defined as the concentration of con A/ml/1 x 10(6) cells corresponding to 10% and 95% agglutination, minimal and maximal agglutination occured at 0.56 ug, 19.98 ug for human erythrocytes at 0.56 ug, 224 ug for rat erythrocytes at 0.08 ug, 1.43ug for rabbit erythrocytes at 0.12 ug, 14.8 ug for sarcoma 180-mouse ascites cells respectively. The order of inhibitory activity of alpha-methyl-D-mannopyranoside (alphaMM) for each corresponding cells from the highest inhibition was human erythrocytes, rat erythrocytes, sarcoma 180 mouse ascites cells and rabbit erythrocytes. The concentrations of alphaMM required for 50% inhibition per ml of the final concentration in the hanging drop per 1 x 10(7) cells were 0.565 umoles for rabbit erythrocytes, 0.072 umoles for rat erythrocytes, 0.018 umoles for human erythrocytes and 3.677 umoles for sarcoma 180 mouse ascites cells, respectively. From our experimental results we conclude that the cytoagglutination activity was increased with con A, the inhibitory activity with alphaMM in the presence of con A was decreased, however the sarcoma 180 mouse ascites cells revealed a contradictory result, and might be due to the topological distribution of agglutination site changes to a distribution more favorable for agglutination.