73 TRANSACTIONS OFTHE ROYAL SOCIETY OFTROPICAL MEDICINE AND HYGIENE, VOL. 70. No. 1.1976. Schistosomal pigment in human and murine infections with Schisfosoma mansoni J. A. GRIMAUD Laboratoire d’dnatomie Pathologique Exp&imentale, Institut Pasteur de Lyon, France R. BOROJEVIC” Labdratorio Central GonGalo Monk, FUSEB, 121 Raa Valdemar Falc~o, Brotas, Salvador, Bahia, Bras2 H. ARAUJO DOS SANTOS Departamento de Medicina, Faculdade de Medicina, Universidade Federal da Bahia, Salvador, Bahia, Bras2 * Expert de la Cooperation Technique Francaise Summary Schistosomal pigment was studied by optical and electron microscopy in liver biopsies of patients with different clinical forms of schistosomiasis and in livers of mice experimentally infected with Schistosoma munsoni. Phagosomal and residual forms of the pigment are described. The quantity of pigment is low in subclinical and in hepatointestinal forms of schistosomiasis; it is high in young patients with the hepatosplenic form, and low in the old ones. The participation of the pigment in the pathogenesis of schistosomal lesions is discussed. Introduction The presence of schistosomal pigment is a constant characteristic of liver and spleen pathology in experi- mental and human infections by Schistosoma mansoni. In the experimental pathology of schistosomiasis, the quantity of pigment is proportional to the number of adult worms present in the host and to the duration of the infection (KLOETZEL and LEWERT, 1966; RAMADAN and MICHAEL, 1969). In human pathology, the quantity of pigment in the liver and spleen is very variable, ranging from complete absence of pigment to heavy loads present throughout the liver, giving it a dark grey colour. The schistosomal pigment represents a product of the digestion of erythrocytes, ingested and eliminated by the worms in the portal circulation. It is chemically composed of a complete porphyrin ring and of a large and probably proteinaceous molecule (UOETZEL and LEWERT, 1966; HOMEWOOD and JEWSBURY, 1972). The presence of iron in it is still under investigation. The morphology of the pigment in human schistosomiasis has not been described. Its influence on the host-parasite relationship is not clear, and its role in the histogenesis of the schistosomal lesions is still unresolved. Materials and methods The experimental material was collected from randomly bred Swiss albino mice, infected with 60 to 90 cercariae of both sexes, or with 200 to 500 cercariae of only one sex, of the LE strain (Belo Horizonte) or of the FS strain (Salvador) of S. mansoni. The human material, listed in Table I, was collected The authors are grateful to Professor Z. A. Andrade, Deoartment of Pathologv. Facultv of Medicine, Federal University of Bahia, for advice and guidance of this work. Dr. J. C. Bina is gratefully acknowledged for valuable participation in the clinical work. We wish to thank Mrs. L. P. de Ceccatty for her technical assistance. This investigation was supported by the Conselho National de Pesquisas, Brasil. in the “Hospital Prof. Edgard Santos”, Federal Univer- sity, Salvador, Bahia. The patients are divided into two groups: The first one includes all the subclinical cases, and those where disorders of intestinal transit and abdomi- nal pain are the main clinical findings, with a slightly enlarged but elastic liver, and without an intensive periportal fibrosis. The second group includes patients with typical hepatosplenic syndrome, having an enlarged liver, hard and nodular on palpation, clinical signs of augmented portal pressure, an enlarged spleen and, upon histo- logical examination, characteristic Symmers’ fibrosis. The second group is subdivided according to the age of the patients. The presence of the pigment in histological prepara- tions is estimated arbitrarily as low (+), medium (+ +) or high (+ + +). It should be remembered that only the larger deposits can be seen by optical microscopy, and that the small inclusions of the phagosomal form, described below, can only be seen by electron microscopy. Surgical liver and spleen biopsies were taken during splenectomy operations of patients with a severe hepato- splenic form of schistosomiasis. Percutaneous needle biopsies of liver were done in cases of hepatointestinal or milder hepatosplenic forms of schistosomiasis. Small fragments of fresh tissue were fixed for optical microscopy in 10% buffered formalin, and for electron microscopy either in glutaraldehyde (4%) buffered in sodium caccodylate (0,3M), followed by osmification, or ‘in osmic acid (1 ‘A) buffered in sodium caccodylate (0,3M), at 4”C, for 90 minutes. Dehydration was carried out in ethanol and propylene oxide, followed by embed- ding in epoxy-resin. Ultra-thin sections for electron microscony were done using a Reichert OMU-2 micro- tome, contrasted with uranylacetate/lead citrate solutions (Revnolds). and observed on the Hitachi HU-II-C and Philips EM-300 microscopes, under 60 and 80 kW. Control preparations were treated with conventional histological methods and examined, as semi-thin sections, under light microscopy.