Marked reduction of ANAE reactivity of T cells in the lymphoid tissues of monkeys treated with multiple high doses of human beta interferon.

We report a histological study of the organs and tissues of cynomolgus monkeys which had received multiple high doses of human beta interferon (IFN). There were dense aggregations of small lymphocytes without the acid alpha-naphthyl acetate esterase (ANAE) reactivity in the thymus-dependent areas (TDA) of lymphoid tissues, indicating that the T mu cells of IFN-treated monkeys had lost this characteristic enzyme. This change of T mu cells in the tissues was not accompanied by a change in circulating T mu cells.