Myasthenia gravis (MG) is a neuromuscular disorder mediated by autoantibodies against the nicotinic acetylcholine receptor (AChR) on the postsynaptic membrane of the neuromuscular junction. The production of antibodies is regulated by T cells by means of immunoregulatory cytokines. To investigate the involvement of TNF-alpha, lymphotoxin (LT), IL-6, IL-10, IL-12 and perforin in MG, numbers of cytokine mRNA expressing blood mononuclear cells (MNC) were examined in patients with MG and controls. LT belongs to the Th1 cell related cytokines, IL-6 and IL-10 to the Th2 type, TNF-alpha is produced by both Th1 and Th2 cells, IL-12 induces T cell switch towards the Th1 type and perforin is an effector molecule inducing cell lysis. Short term culture of MNC with AChR revealed augmented levels of AChR-reactive TNF-alpha, LT, IL-6, IL-10, IL-12 and perforin mRNA expressing cells in MG compared to levels obtained without AChR or in presence of control antigen. AChR-reactive TNF-alpha, IL-6, IL-10, IL-12 and perforin mRNA expressing cells were higher in MG than controls. These findings suggest that the cytokines TNF-alpha, LT, IL-6, IL-10 and IL-12, and the cytolytic effector molecule perforin are also involved in MG.