La enfermedad del adyuvante en ratas infectadas experimentalmente con Trypanosoma cruzi

Abstract

Se estudió la evolución de la artritis por adyuvante en ratas que habían sido infectadas previamente con Trypanosoma cruzi, con el objeto de evaluar su competencia inmunológica a través de la respuesta artrítica. La artritis por adyuvante se indujo en ratas adultas, endocriadas de ambos sexos, con 0.1 mi de adyuvante completo de Freund en la almohadilla plantar, en 2 lotes: a) inyectadas 90 días antes con 1 x 10(6) T. cruzi y b) testigos normales simultáneos. Se midieron, la lesión artrítica macroscópicamente con una escala semicuantitativa, y con microscopía óptica la histopatología de la lesión local y la del corazón, a los 180 días post-infecoión. La magnitud de las lesiones artríticas en las ratas con T. cruzi fue significativamente menor (p < 0.001) que la de los testigos, en todo el período. El infiltrado inflamatorio local, formado por linfocitos, plasmocitos y macrófagos fue significativamente menor (p < 0.001) en las ratas chagásicas, con respecto al de los testigos. Se postula que en las ratas que recibieron T. cruzi la respuesta artrítica menor podría deberse a una competición antigénica con los determinantes del parásito o a mecanismos inmunosupresores que interfieren en la producción de la entidad experimental.

Absence of experimental cross-protection induced by a Trypanosoma cruzi-like strain isolated from bats

“…In this context, participation of adjuvants becomes important because of their ability to focus the immunological response to a cellular or humoral pattern that depends on the activated T-cell populations and the cytokine profile produced. In the present study, we used Freund's adjuvant, which can generate toxic effects in spite of its T H 1-type stimulating properties 33 , thereby leading to controversy relating to protection induction 20 .…”

Administration of interferon-<FONT FACE=Symbol>g</font> to pregnant rats reverses the depressed adjuvant-induced arthritis of their chronically Trypanosoma cruzi-infected offspring

“…The second group was infected with an sc injection of 10 6 living trypomastigotes at 7, 14, and 21 days after mating, plus treatment with RrIFN-g as administered to group 1. Pregnant rats were infected at weekly intervals in an attempt to produce a more evident infection, considering that infection of adult rats, pregnant or not, results in a scarcely noticeable acute disease (3,15). A similar infection schedule was applied to group 3, which received physiological saline instead of RrIFNg.…”

“…Kinetic studies demonstrated that early arthritic signs are noticeable 7 days after induction, and AA is fully developed by the end of the second week postinduction. Microscopy studies have revealed that affected joints are heavily infiltrated by lymphocytes, macrophages, epithelioid and giant multinucleate cells resembling a chronic granulomatous reaction (16). The arthritis was evaluated at 7, 15, 20 and 30 days postinduction by direct examination of individual joints using a semiquantitative scale (10).…”

“…In fact, challenge with living trypomastigotes at weaning is followed by a self-controlling acute infection characterized by easily noticeable parasitemias lasting up to 30 days postinfection (pi), together with the synthesis of specific antibodies that reach their maximum titers at 30 days pi, and persist within these levels thereafter. Well after the acute episode is resolved, 60 to 80% of these rats develop a mild chronic focal myocarditis consisting of mononuclear cell infiltration and destruction of myocardial muscle fibers (1)(2)(3)(4).…”

“…Because our rats become highly resistant to T. cruzi when challenged in adult life (15), IFN-g was also given to rat mothers in an attempt to reproduce what may happen when the host is effectively infected and synthesis of endogenous IFN-g is more likely to be increased. Our model proved to be useful in demonstrating that administration of IFN-g to pregnant rats largely protected their offspring against further challenge with T. cruzi, with young born to mothers that had also been infected during gestation displaying the lowest parasitemias (14).…”