Effects of glutamine and ethanol in vitro on lymphocytes from human alcohol abusers and non-abusers

The amino acid L-glutamine is essential for the function of both resting and stimulated lymphocytes, and its uptake is significantly increased after stimulation. The effects of ethanol on the immune system appear to be widespread and significant, and its role as an osmolyte has recently been proposed to be important. The in vitro effect of concur rent glutamine deprivation and ethanol exposure in different osmotic conditions was investigated with respect to the proliferative capability of lymphocytes in vitro from both alcohol abusers and non-abusers, and also the kinetics of glutamine transport across peripheral blood lymphocytes (PBL) membranes from non-abusers. In a physiologically nor mal situation ethanol increases osmolality, and tonicity remains balanced. However, in situations of electrolyte imbalance ethanol addition may result in osmolality remaining near nor mal levels, but with hypotonicity. It was found that a lack of glutamine and iso-osmotic hypotonic high ethanol concentrations caused a greater inhibition of mitogen-stimulated lymphocyte proliferation than either factor alone. This was true for PBL from both non-abusers and abusers of alcohol. There was no change in membrane permeability and active transport of glutamine into lymphocytes from non-abusers that were stimulated in vitro in various conditions of ethanol, osmolality and tonicity. While lymphocyte proliferation may be inhibited in cer tain conditions and this is fur ther affected by a lack of glutamine, the capacity for active glutamine transport was maintained, perhaps due to its essential role in lymphocyte metabolism.