Suppressor cell activity in a male infant with T-and B-lymphocyte dysfunction treated with thymosin.

A male infant with bilateral iris coloboma who had had repeated infections and malabsorption was studied. The levels of total lymphocytes and of T and B cells were normal or high, but IgA became undectable and IgG low, whereas IgM was normal. His lymphocytes did not respond to phytohemagglutinin (PHA), concanavalin A, pokeweed mitogen (PWM) or in mixed lymphocyte reactions (MLR), nor did they respond in vitro when thymosin was included in the test systems. He was skin-test-negative, even to dinitrochlorobenzene. His crudely isolated T lymphocytes and the supernatant of his PHA-stimulated lymphocytes inhibit the response of normal lymphocytes to PHA, PWM, and in MLR. During thymosin treatment skin test and lymphocyte reactivity to mitogen remained negative. He became faintly positive in MLR, and the suppressor activity in the supernatant of his PHA-stimulated lymphocytes no longer inhibited the response of normal lymphocytes to PHA, PWM, or in MLR. In parallel with thymosin treatment he showed quite marked clinical improvement.