The anti-inflammatory effect of LS 2616 and poly I:C in coxsackievirus B3 induced murine myocarditis.

We have studied the effects of immunotherapy in coxsackievirus B3-induced myocarditis in male BALB/c mice. A single i.p. injection of the synthetic interferon inducer poly I:C conferred an almost total protection from lethality when administered at 0 h or 24 h after infection. Poly I:C treatment at 48 h after infection, as well as daily i.p. injections of the quinoline-3-carboxamide LS 2616, a new stimulator of NK-cell activity, gave no protection from lethality. The inflammatory lesions and necrosis in the ventricular myocardium 7 days after virus inoculation (3.1% of section area) were reduced in the poly I:C (24 h) treated group (1.0% of tissue section area). A less pronounced reduction was seen in the LS 2616 and poly I:C (48 h) treated groups (1.7 and 1.9% of tissue section area, respectively). The response patterns of the studied lymphocyte subpopulations were different with these two compounds, TIB+ (pre-B)-cells increased with poly I:C treatment (49%), but decreased with the LS 2616 treatment (65%). The Lyt 1+ (pan T)-cells responded similarly. Poly I:C (24 h) and LS 2616 treatment tended to increase the number of class II expressing cells (1.9- and 2.9-fold, respectively). The titer of neutralizing antibodies to coxsackievirus B3 was significantly increased in the LS 2616 treated group (1:80) but not significantly so in the poly I:C treated groups (1:40) as compared to the infected and non-infected control groups (1:20 and less than 1:5, respectively).