Thiol containing antioxidant drugs and the human immune system.

The over production of toxic oxygen species (TOS) by the phagocytic cells involved in inflammatory processes plays a crucial role in generating the immune defects which characterize both infections and neoplastic diseases. Since the thiol containing drugs, and N-acetylcysteine possess a high capacity for scavenging and inhibiting TOS, the question of whether these substances are able to protect, in vivo as well as in vitro, the function of lymphocytes isolated from the peripheral blood in patients suffering from chronic pulmonary diseases (CPD) was investigated. The lymphocytes isolated from healthy donors as well as those from CPD patients exposed in vitro to TOS showed a reduced viability and an impairment of functions in: (a) the ability to express HLA Class II and TAC antigens and (b) the capacity to stimulate and proliferate in allogenic (MLR) and autologous mixed lymphocyte reactions (AMLR). The presence of NAC or CAT blocked this toxicity. Cells isolated from healthy donors and patients following treatment with NAC were less sensitive to the in vitro toxicity of TOS.