Antigen-specific Suppressor T Cells Prevent Cardiac Injury in Balb/c Mice Infected with a Nonmyocarditic Variant of Coxsackievirus Group B, Type 3

Two variants of coxsackievirus group B, Type 3 (CVB3o and CVB3M) infect Balb/c cardiac tissue equally, but only one variant (CVB3M) induces myocarditis. Various studies indicate that disease resistance in CVB3o-infected mice results from generation of suppressor cells. Low-dose cyclophosphamide (50 mg/kg body weight) treatment enhances inflammation in both CVB3M and CVB3o-infected animals, which clearly demonstrates that CVB3o has the capacity to induce disease, but inhibitory factors must exist preventing myocarditis. Spleen cells obtained from mice 10 days after CVB3o inoculation inhibited myocarditis induction in CVB3M-infected recipients, which confirms the presence of suppressor cells in these animals. The suppressor cell belongs to the Lyt 2+ subclass of T lymphocytes and specifically interferes with CVB3-induced myocarditis but fails to inhibit T-cell-mediated cardiac injury triggered by an unrelated virus, encephalomyocarditis virus.