EXPERIMENTAL PARASITOLOGY 90, 286–289 (1998) ARTICLE NO. PR984343 RESEARCH BRIEF Schistosoma mansoni: The Circulating Cathodic Antigen Forms an Abundant Product of 41/42 kDa in the Urine of Infected Patients Hesham H. Abdeen, 1 Abdel-Fattah M. Attallah, 2 Hanan I. El-Mohamady, Robert A. Harrison, 3 and Moustafa M. Mansour US Naval American Medical Research Unit-3 (NAMRU-3), Cairo, Egypt Abdeen, H. H., Attallah, A.-F. M., El-Mohamady, H. I., Harrison, antigen would be detectable mostly in a free form, which is R. A., and Mansour, M. M. 1998. Schistosoma mansoni: The circulating not conjugated in immune complexes as in serum. In addition urine cathodic antigen forms an abundant product of 41/42 kDa in the urine sampling is a noninvasive technique under field conditions (Ripert of infected patients. Experimental Parasitology 90, 286–289. et al. 1988). Index Descriptors and Abbreviations: trematode; Schistosoma man- Due to their production in relatively large amounts and direct contact soni; diagnosis; urine; circulating anodic antigen (CAA); circulating with the immune system, circulating antigens exist as major immuno- cathodic antigen (CCA); monoclonal antibody (MAb); soluble worm gens during the course of infection. We were thus encouraged to antigen preparation (SWAP); phenol sulfuric test active peak (PSAP). generate diagnostic monoclonal antibody(s) (MAb) from chronically infected mice, which could be used for detection of circulating anti- gen(s) in infected urine. A panel of MAbs was prepared, as previously described (Goding 1987), using splenocytes of Balb/c mice infected with 50 S. mansoni cercariae after 22 weeks of infection. The spleno- cytes were fused to P3NS1 myeloma cells and the clones producing Schistosome circulating antigens are a group of antigens excreted/ antibodies against soluble worm antigen preparation (SWAP) were secreted by the parasite in the blood stream of the host, where they selected by ELISA. Control ascites fluid was prepared from animals are cleared from the circulation and excreted mainly in the urine. The injected with myeloma cells. Four IgM MAbs were found to recognize gut-associated antigens; circulating anodic antigen (CAA) (Berggren a major band of about 41/42 kDa and three minor bands of 53, 60, and Weller 1967) and circulating cathodic antigen (CCA) (Carlier et and 62 kDa, in pooled concentrated urine from Egyptian males infected al. 1975), are the most studied. Detection of CAA and CCA, in the with S. mansoni (10 patients with an average egg output of 600 egg/ blood and urine of patients, provided the basis of candidate-improved g stool, as determined by the Kato thick-smear technique). Figure 1 assays for the diagnosis of schistosomiasis (Deelder et al. 1994). How- shows the reactivity of one of these MAbs, named B 3 C 9 , to the urine ever, the use of urine samples over serum samples offers several concentrate from infected and uninfected humans. Urine concentrates advantages. Detection of a circulating antigen in the urine would be were prepared by ammonium sulfate precipitation at 50% saturation, easier due to the concentration effect taking place in the kidneys. The incubation overnight at 4°C, centrifugation in a bench microcentrifuge at 14,000 rpm at 4°C for 10 min, and resuspension of pellets in 1/25 of the original volume in 1X SDS-PAGE loading buffer supplemented 1 Address for correspondence: Commanding Officer, NAMRU-3 with 5 M urea. Urine concentrates were boiled for 5 min and cleared (Attn Code 101F), FPO AE 09835-0007, U.S.A. Address for reprint by centrifugation at 14,000 rpm for 10 min before loading on SDS- requests: Research Publication Branch, NAMRU-3 (Attn Code 101F), PAGE gels. Urine from normal humans was provided by uninfected FPO AE 09835-0007, U.S.A. laboratory personnel and treated as for urine from schistosomiasis 2 Present Address: Gastro-enterology Center, Mansoura University, patients. Mansoura, Egypt. The MAb B 3 C 9 showed a typical reactivity to CCA when compared 3 Present Address: Liverpool School of Tropical Medicine, Liv- erpool, UK. to an anti-CCA MAb named 5H11, previously used for detection of 286 0014-4894/98