Memórias do Instituto Oswaldo Cruz Fundação Oswaldo Cruz, Fiocruz ISSN: 1678-8060 EISSN: 1678-8060 Vol. 91, Num. 1, 1996, pp. 81-82

RESEARCH NOTE

Trypanosoma rangeli and Trypanosoma cruzi: Cross-reaction among their Immunogenic Components

A Saldana, OE Sousa

Center for Research and Diagnosis of Parasitic Diseases (CIDEP), Faculty of Medicine, University of Panama, Estafeta Universitaria, Panama, Panama

Code Number: OC96013
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It has been demonstrated that immuno-modulating mechanisms induced by epimastigotes of Trypanosoma rangeli, an assumed harmless human parasite, may have relevance to protection against Trypanosoma cruzi, the causative organism of Chagas' disease (B Basso et al. 1991 Am J Trop Med Hyg 44: 413-419). Evidently, this finding is related to the previously demonstrated antigenic similarity, between these parasites (D Afchain et al. 1979 J Parasitol 65: 507-514, B Basso et al. 1989 Rev Lat-amer Microbiol 31: 141-146, M Grögl, RE Kuhn 1984 J Parasitol 70: 822-824, F Guhl, CJ Marinkelle 1982 Ana Trop Med Parasitol 76: 361). However, at the present time it is not known which T. rangeli antigens can elicit antibodies capable to recognize T. cruzi components. In order to clarify this matter, we used the immunoblotting technique to delineate the cross-reactivity among the immunogenic components of these parasites.

The parasites used were isolated from humans in central Panama. Clones derived from single cell isolates (JA Dvorak 1985, Rev Soc Bras Med Trop 18 (Suppl): 29-38) of T. rangeli (LMCL2) and T. cruzi (MA-081A) were characterized by studies of morphology, intracellular multiplication measured in vitro and infectivity for vector salivary glands. Flagellates were cultivated and lyophilized following procedures designed previously (NH Vattuone, JF Yanovsky 1971 Exp Parasitol 30: 349-355, A Saldana 1990 Immunoparasitological Studies of Trypanosoma cruzi clones from Panama, MSc Thesis, I. Karolinska-Stockholm, 90 pp). The lyophilized T. rangeli and T. cruzi epimastigotes were used in the production of mouse antibodies as ascitic fluid (AS Tung et al. 1976 J Immunol 116: 676-681, AE Horna 1992 Biochemical and Immunological Characterization of Trypanosoma rangeli (Tejera 1920) strains affecting rural populations of Central and South America. MSc Thesis, I. Karolinska-Stockholm, 100 pp). To demonstrate the antibody cross-reactivity we followed procedures described earlier (EC Rostjord et al. 1990 J Parasitol 76: 698-702).

Previous reports suggested that exposure to T. rangeli antigens might modify the pathology due to T. cruzi (Grögl, Kuhn loc. cit., F Guhl et al. 1987 Parasitol 94: 475-484, L Hudson et al. 1988 Parasitol 96: 449-460). Nevertheless, as far as we know , the first work that demonstrated a partial resistance in T. rangeli-immunized mice against T. cruzi infection was done by Basso et al. (loc. cit.). However, the studies of T. rangeli immunogenic components seems to be just beginning.

Our results (Figs 1, 2) revealed that there are several common epitopes among T. rangeli antigens and between T. rangeli and T. cruzi polypeptides. The antibodies eluted from the regions A, B, C, D, E and F recognized additional bands to the bands from which they were separated either in T. rangeli or T. cruzi immunoblotting profiles. Most of them cross-reacted with antigens in region B ( 81, 76 and 71 Kda). However, when the antibodies eluted from regions of 34 (G), 29 (H) and 24 Kda (I) were used, more specificity was found. The antibodies from the bands of 34 and 29 Kda recognized, without differences, antigens with similar molecular weights in the T. rangeli or T. cruzi profiles. This may, therefore, represent the expression of two antigens, highly conserved, which apparently are a second group of immunodominant determinants responsible for the observed cross-reactivity.

An additional finding was the specific recognition pattern noted with the antibodies from the 24 Kda region, apparently this antigen shows a third restrictive group of immunodominant epitopes, expressed either in the 24 Kda polypeptide of T. rangeli and in the 23 Kda region of T. cruzi.

Even with these cross-reactions, it should be kept in mind, that it is possible to find specific epitopes in each one of these molecules. The identification of specific epitopes recognized by monoclonal antibodies should facilitate studies which aim at settling this possibility.

Finally, research on purification and immunochemistry of these T. rangeli antigens, which cross-reacted with T. cruzi components, could be important on the diagnostic and management of Chagas' disease.

Fig. 2: immunoblot profile of Trypanosoma cruzi antigens. Anti-T. rangeli antibodies were separated as in Fig. 1. The strips A-I show the patterns obtained when eluted antibodies interacted with total T. cruzi antigens. The strip J show the T. cruzi antigens recognized by total anti-T. rangeli antibodies. Right arrows indicate the position of molecular weight markers in Kda.

Fig. 1: immunoblot profiles of Trypanosoma rangeli antigens. Anti-T rangeli antibodies were separated from selected areas on the T. rangeli antigenic profile (strip AP). The strips A-I show the patterns obtained when eluted antibodies interacted with total T. rangeli antigens. Right arrows indicate the position of molecular weight markers in Kda.

Received 13 December 1994

Accepted 4 October 1995

Copyright 1995 Fundacao Oswaldo Cruz

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