Significance of schistosomal granuloma modulation

Hepatic Schistosoma mansoni periovular granulomas undergo changes in size, cellular composition and appearance with time. This phenomenom, known as "i mmunological modulation", has been thought to reflect host immunological st atus. However; as modulation has not been observed outside the liver partic ipation of local factors, hitherto little considered seems crucial. Compone nts of the extracellular matrix of periovular granulomas of the mouse were particularly studied in three different organs (liver, lung and intestine) and during three periods of infection time (acute, intermediate and chronic ) by means of histological, biochemical and imunofluorescence techniques, w hile quantitative data were evaluated by computerized morphometry in order to investigate participation of local factors in granuloma modulation. Resu lts confirmed modulation as a exclusively hepatic phenomenom, since pulmona ry and intestinal granulomas, formed around mature eggs, did not change siz e and appearance with time. The matricial components which were investigate d (Type I, III and IV collagens, fibronectin, laminin, proteoglycans and el astin) were found in all granulomas and in all organs examined. However; th eir presence was much more prominent in the liver. Elastin was only found i n hepatic granulomas of chronic infection. The large amount of extracellula r matrix components found in hepatic granulomas was the main change respons ible for the morphological aspects of modulation. Therefore, the peculiar e nvironment of the liver ultimately determines the changes identified in sch istosomal granuloma as "modulation".