Influence of the level of dietary ethanol in mice with murine AIDS on resistance to Streptococcus pneumoniae

Abstract

Chronic ethanol consumption impairs cellular immune functions. This may explain the increased occurrence of various opportunistic infections in heavy ethanol users. Immunological alterations associated with Acquired Immune Deficiency Syndrome (AIDS) also permit more opportunistic infections. In this study, we used a murine model of retrovirus infection induced by LP-BM5 murine leukemia virus. The combined effects of ethanol use and early retroviral infection (prior to the development of AIDS) on resistance to Streptococcus pneumoniae were investigated. Consumption of ethanol by non-retrovirus-infected mice resulted in decreased resistance to S. pneumoniae. However, retrovirus-infected mice fed a diet containing high concentrations of ethanol (6 and 7% v/v) exhibited a greater resistance to S. pneumoniae infection than retrovirus-infected mice fed diets with lower concentrations (5%) or no ethanol. The total number of white blood cells also decreased as serum ethanol levels increased. There were also fewer lymphocytes and more neutrophils and monocytes in retrovirus-infected mice fed ethanol. Diet consumption decreased as the concentration of ethanol increased in the diet. Consumption was dependent upon the dark-light cycle. The highest diet consumption was observed during the first 4 hr of the dark period. The level of ethanol in serum was influenced by the amount of the diet consumed and its ethanol concentration. Both retrovirus infection and ethanol consumption effected survival after S. pneumoniae infection.