Enhancement of coxsackievirus B3 myocarditis in mice by lobenzarit disodium through inhibition of splenic pan T cells.

OBJECTIVE: The aim was to test the efficacy of the immune system modulator lobenzarit disodium in the treatment of coxsackievirus B3 myocarditis.
METHODS: Two week old C3H/He mice were inoculated with 10(3) plaque forming units of coxsackievirus B3. Lobenzarit disodium, 25 mg.kg-1.d-1, was given subcutaneously daily on days 0-14 (experiment I; group 2) and days 14-28 (experiment II; group 4). Both treated groups were compared to infected controls for each experiment (groups 1 and 3). For the analysis of splenic lymphocyte subsets, additional mice in untreated and treated groups were killed on d 7, and the percentages of Thy 1.2 (CD3), L3T4 (CD4), Ly 2 (CD8) subsets were analysed by laser flow cytometry (experiment III).
RESULTS: In experiment I, the survival rate in the lobenzarit treated group was significantly lower than in the controls (2/11 v 8/11). Cellular infiltration and myocardial necrosis in the lobenzarit group were more severe. Myocardial virus titres and serum neutralising antibody titres did not differ significantly between the two groups. In experiment II, the survival rate (7/9 v 13/13) and cardiac pathology between the two groups did not differ significantly. In experiment III, the percentage of the Thy 1.2 subset (CD3) in the treated group was significantly lower (p < 0.05) than in the control group, at 36.0(SD 2.9)% v 42.8(5.8)%.
CONCLUSIONS: Lobenzarit disodium decreased splenic pan T cells and aggravated both clinical course and cardiac pathology in acute murine coxsackievirus B3 myocarditis.