Sex Differences and the Effects of Alcohol on Immune Response in Male and Female Rats

Although it is clear that both alcohol and sex hormones impact immune function, very little information is available on the effects of alcohol on immune response in males versus females. We decided to determine if the alterations in immune response resulting from alcohol feeding might be expressed differently in males and females. To accomplish this we utilized pair-fed male and female Sprague-Dawley rats. Animals were fed a liquid diet for 60 days containing 30% of their calories as ethanol, and after 1 week this concentration was increased to 45% ethanol. Controls received liquid control diet of the same caloric and nutritional composition, and immune status was monitored with in vivo and in vitro techniques. Ethanol feeding significantly reduced the phytohemagglutinin skin response in males ( p = 0.020) and females ( p = 0.012). The concanavalin A blastogenic response of spleen cells prepared from female rats fed ethanol was significantly depressed with respect to spleen cells prepared from female rats fed the control diet ( p = 0.0071). Alcohol also appeared to depress spleen cell blastogenic response in males, but this trend did not quite reach significance ( p = 0.071). Spleen cells from groups of ethanol and control male and female rats were labeled with fluorescent monoclonal antibodies and run on a Fluorescent-Activated Cell Sorter. Ethanol significantly increased the percentage population of CD4 (T-helper cell) in males ( p = 0.017), but not in females, and promoted an apparent, although nonsignificant, increase in the CD4/CD8 ratio in both sexes. An ELISA was used to measure IgM and IgG antibody elaborated by pokeweed mitogen-stimulated spleen cells in cultures. Ethanol feeding increased both IgM secretion ( p = 0.0001) and IgG secretion ( p = 0.034) in cells from females but not males, and female cells secreted significantly more immunoglobins than did male cells.