Fluorescent antibody technics were used to determine the localization and distribution of Schistosoma mansoni antigen in tissue cells, the presence of circulating antibody, and the sites of antibody production or in vivo antigen-antibody combination. The experiments were performed in mice after a primary infection with cercariae, after several challenges, and after antigen stimulation and challenge. Evidence of the presence of circulating antibody was first observed at 20 days in the inhibition fluorescent antibody test, at 25 days in the indirect fluorescent antibody test, at 42 days with the cercarial fluorescent antibody test, and at 47 days in the Cercarienhullen reaction.
Sites of antibody production or in vivo antigen-antibody combination were observed in inflammatory cells of the portal tracts, especially those along the smaller arteries, and in granulomas and isolated cells in the parenchyma of the liver; in the perivascular tissue cells, isolated parenchymal cells and granulomas of the lungs; and in cells in the center of the follicles and of perivascular infiltration in the spleen and lymph nodes.
The sites of antigen deposition after a single exposure were the perivascular inflammatory infiltrate and histiocytes in the parenchyma of the liver and lungs, the granulomas of the liver, and the neutrophils in the sinuses and the perivascular cells in the spleen. In the reexposed and antigen-stimulated groups, the same areas were positive for antigen, and in addition, antigen was detected in the endothelium of the blood vessels in the lung and some cells in the lymph nodes.
Present address: Department of Pathology, Faculdade de Medicina, Universidad do Recife, Recife, Brazil; Kellogg Fellow at the Department of Tropical Medicine and Public Health, Tulane University School of Medicine, January–July, 1962.