DESCRIPTION: Immunosuppression by alcohol, manifested by increased susceptibility to bacterial and viral infections, is characterized by the disruption of normal cytokine responses by cells of the immune system. The NFkB family of transcription factors is a critical regulator of cytokine responses, coordinating the transcriptional response to immune stimuli. Preliminary data is presented demonstrating that ethanol specifically inhibits the activation of two distinct NFkB complexes in myeloid cell lines. Ethanol inhibits the signal induced phosphorylation of the NFkB inhibitor IkappaBalpha, thereby blocking the translocation of NFkB to the nucleus and the activation NFkB response genes. The formation of a novel, activated Bcl-3/p50 complex is also inhibited in the presence of ethanol. An experimental strategy is proposed that will focus on the mechanism by which ethanol inhibits IkappaBalpha phosphorylation. The sensitivity of the NFkB signaling pathway to ethanol differs depending on the cell type and the specific inducing agent, comparing the response using several well-characterized cell models and activation protocols will facilitate the identification of the upstream activating events modulated by ethanol. Preliminary data show that ethanol suppresses activation of the recently characterized IkappaB kinase complex, and its upstream regulator MEKK1. These studies will be extended and intensified to identify the molecular target or the interaction of ethanol with the NFkB signaling pathway. A similar strategy will be applied to the Bcl-3/p50 activation pathway. To gauge the significance of NFkB for immunosuppression by ethanol, the effects of ethanol on differentiation and activation in response to cell stimulation by inducers of NFkB will be quantified. Parameters to be studied include marker protein expression, growth arrest, cell adhesion and phagocytosis. Parallel experiments will examine the ethanol sensitivity of NFkB target gene expression, including cytokines, anti-apoptotic proteins, and viral promoters. The data obtained should allow the functional consequences of NFkB inhibition for the immune system to be predicted and tested with greater accuracy.