Age-related increase in resistance to acute Trypanosoma cruzi infection in rats is associated with an appropriate antibody response

PASCUTTI MF; BOTTASSO O; HOURQUESCOS MC; WIETZERBIN J; REVELLI S; BOTTASSO OSCAR

SCANDINAVIAN JOURNAL OF IMMUNOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Oslo; Año: 2003 vol. 58 p. 173 - 179

0300-9475

Inoculation at weaning with Trypanosoma cruzi in inbred ?l? rats resulted in aself-resolving acute infection characterized by marked parasitaemias, whereaschallenge to adult rats revealed a mild disease with extremely low parasitaemias.To explore the mechanisms underlying such age-associated differences in diseaseoutcome, we analysed the in vitro replication of T. cruzi, nitric oxide andtumour necrosis factor-a (TNF-a) production in peritoneal macrophages(PMs), the serum concentrations of the specific immunoglobulins (Igs) IgMand IgG, antibodies exhibiting lytic activity against bloodstream forms of T. cruziand circulating levels of nitrate, TNF-a and interferon-g (IFN-g). Macrophagesfrom young rats were as effective as their adult counterparts for restrainingintracellular parasite replication. When stimulated with IFN-g, culture supernatantsfrom young PMs contained higher amounts of nitrite and TNF-a.Serum samples from 4 and 7 days post infection revealed easily detectableamounts of nitrate, with values being further augmented by day 7 post infectionand significantly higher in the young group. TNF-a levels were only detected inthe young group by day 7 post infection. Both groups had increased amounts ofIFN-g in their sera, although in adult rats, this trend was followed by asignificant drop at day 7, with young rats showing values still higher by thesame time point evaluation. In contrast, young rats presented significantly lowerlevels of IgM and IgG antibodies during the first week of infection. Increasedresistance in adult rats seems to be the result of a more appropriate antibodyproduction.