Administration of interferon-gama to pregnant rats reverses the depressed adjuvant-induced arthritis of their chronically Trypanosoma cruzi-infected offspring

We demonstrated that administration of interferon gamma (IFN-gama) to the inbred "l" strain of pregnant rats conferred partial resistance on their offspring to challenge with Trypanosoma cruzi. We now examine if this intervention also modifies the reportedly immunodepressed cellular responses which occur during chronic infection. Offspring were born to mothers undergoing one of the following procedures during gestation: subcutaneous injections of recombinant rat IFN-gama, 50,000 IU/rat, five times/week for 3 weeks, which was started on the day of mating (IFN-Mo); infection with 106 trypomastigotes of T. cruzi at 7, 14, and 21 days after mating plus IFN-gama treatment as given to the former group (TcIFN-Mo); the same protocol except that physiological saline was injected instead of IFN-gama (Tc-Mo); injection of physiological saline only (control-Mo). All offspring groups (N = 8-10/group) were infected at weaning and were assessed 90 days later for their adjuvant-induced arthritic response or levels of major T cell subsets in spleen and lymph nodes. TcIFN-Mo and IFN-Mo offspring showed a reestablished arthritic response, which remained within the range seen in controls. Immunolabeling studies on parallel groups of 90-day-infected offspring showed that the inverse CD4/CD8 cell ratio that is usually seen in lymphoid organs from these chronically infected rats (median 0.61) appeared to have recovered in the TcIFN-Mo and IFN-Mo groups (median 1.66 and 1.78, respectively) and was not different from uninfected controls (1.96). These studies indicate that early stimulation with IFN-gama is able to reverse the immunosuppressive state that is usually present during the chronic period of the experimental infection.

Depressed adjuvant arthritis in rats transferred with spleen cells from Trypanosoma cruzi-infected syngeneic donors

In the present we investigated whether the attenuating effect of chronica Trypanosoma cruzi (Tc) infection on adjuvant arthritis (AA) in the rat could be transferred to naive recipients. Transfer of whole spleen cells, but not of serum, from Tc-infected rats reduced AA (x ñ SEM: 11 ñ 0.5) in recipient animals (control values, x ñ SEM: 19 ñ 0.7). Transfer of a T-cell enriched subpopulation from spleen cells of Tc-infected rats (obtained by filtration through a nylon column) resulted in a similar attenuationb of AA (x ñ SEM: 7.5 ñ 2.2). The arthritic response of rats intraperitoneally inoculated with 2 x 10**5 Tc 48h before induction did not differ from that observed in controls. Neither parasites nor specific antibodies were observed in suckling mice inoculated with serum or cell suspensions employed in transfer experiments. Consequently, the depressive effect on AA could not be directly attributed to Tc per se. We hypothesize that a homeostatic immunosuppressor mechanism may be responsible for this phenomenon

Alteraciones electrocardiograficas en individuos infectados con Trypanosoma cruzi con distinto tiempo de residencia en areas de alta endemicidad / Electrocardiographic changes in subjects infected with Trypanosoma cruzi with different time of residence in areas of high endemic incidence

Se estudiaron las alteraciones del ECG (AECG) en individuos infectados chagásicos sisn sintomatología clínica, provenientes de áreas de alta endemicidad (AAE) para el T. cruzi, con distinos tiempos de residencia en esas zonas. De 355 personas evaluadas, 100 de ellas (28%), 48 mujeres y 52 hombres, presentaron signos ECG compatibles cocn una miocardiopatía chagásica crónica. Se constató un incremento en la frecuencia de las AECG con el aumento de la edad de los individuos, considerando 1 signo anormal del ECG (p<0,05) o 2 signos (p<0,001). La edad promedio de los sujetos fue homogeneizada, excluyendo de la muestra aquellos que habían residido en AAE más de 35 años. De esta forma, la frecuencia de AECG (2 signos presentes) en los individuos con más de 20 años en AAE, fue significativamente mayor a la de aquellos con menos de 5 años (p<0,01). Con respecto al tipo de alteraciones, las más comunes fueron BCRD, HBAI y BIRD. La presencia de HBAI fue significativamente superior en los individuos con más de 20 años de residencia en AAE (p<0,02). Se postula que esta prolongada residencia en AAE fovorecería la posibilidad de un mayor número de reinfecciones con el T. cruzi, que justificaría, en parte al menos, las diferencias en las alteraciones del ECG halladas