Enhanced myocardial lesions in chronically Trypanosoma cruzi-infected rats subjected to adult thymectomy.
Control animals and rats infected 90 days earlier, by inoculation of 1 x 10(6) trypomastigotes of Trypanosoma cruzi at weaning, were subjected to adult thymectomy (ATx) or sham operation (S-ATx) and assessed 3 months later for the presence of myocardial lesions and levels of lymph node and spleen T-cell populations. Chronic focal myocarditis (CFM) developed in 78% and 84% of S-ATx or ATx infected rats, respectively. While the two groups of infected rats did not differ as to the occurrence of myocardial lesions, large foci of CFM were more prevalent in ATx infected rats. Chronic T. cruzi (Tc) infection resulted in decreased CD4+ and increased CD8+ lymph node and spleen cell, with CD8+ lymphocytes being lowered to normal values in the spleen of the ATx infected group. It is suggested that ATx might act by interfering with a down-regulating immunoregulatory mechanism, leading to an exacerbation of autoimmune reactions believed to be involved in the generation of myocardial damage.
Bottasso
O A
OA
División Immunología, Facultad de Ciencias Médicas, Universidad Nacional de Rosario, Argentina.
Revelli
S S
SS
Dávila
H
H
Valenti
J L
JL
Musso
O C
OC
Ferro
M E
ME
Romero-Piffiguer
M
M
Morini
J C
JC
D000818:Animals; D016516:CD4-CD8 Ratio; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D002598:Chagas Cardiomyopathy / Q000276:immunology* / Q000473:pathology; D002908:Chronic Disease; D004195:Disease Models, Animal; D015536:Down-Regulation; D007958:Leukocyte Count; D008198:Lymph Nodes / Q000276:immunology; D008297:Male; D051381:Rats; D013154:Spleen / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000276:immunology; D013934:Thymectomy; D014349:Trypanosoma cruzi / Q000276:immunology*