Nonspecific T-suppressors in experimental tick-borne encephalitis.

Suppressor cells inhibiting graft-verus-host reaction under conditions of two-way incompatibility were activated in lymphoid organs of tick-borne encephalitis virus-infected mice. Cells with suppressor activity were found in the thymus, peripheral lymph nodes (LN) and spleen but not in the bone marrow, or peritoneal exudate cells adhering to the plastic surface. The cells were identified as T lymphocytes based on the following properties: sensitivity to anti-theta serum, inability to adhere to plastic surface, and resistance to anti-mouse gamma-globulin serum. The T suppressors were activated 3 days after infection (p. i.) in the thymus and LN and at 4 days in the spleen; they were detectable until the appearance of clinical signs of the disease (8-9 days p. i.).