Junin virus-induced suppressor cells are effective only on the efferent limb of the delayed-type hypersensitivity response.

Junin virus (JV), the etiological agent of Argentinian hemorrhagic fever, induces high mortality in the suckling BALB/c mouse, which correlates with delayed-type hypersensitivity (DTH)-like immune response. In contrast, the adult mouse is resistant to infection, and no DTH response can be detected. An antigen-nonspecific DTH suppressor T-cell activity induced by JV has been described that may be related to adult mouse survival. In this report, we present evidence supporting the inability of such cells, identified here as bearing the L3T4 marker, to affect the normal establishment of a DTH reaction. In the same form, virus-induced suppressor cells were unable to alter the expression of DTH effector cells in the absence of antigen-specific DTH suppressor cells. Besides, we found that a single high dose (200 mg/kg) of cyclophosphamide before or after JV inoculation was unable to alter the activity of virus-induced suppressor cells.