Immunocompetence in the long sleep and short sleep mouse lines: baseline versus primed responses

Two lines of mice which were selectively bred for high (Long Sleep; LS) and low (Short Sleep; SS) reactivities to a sedative dose of ethanol, are also differentiated by agents that act at the GABAA-receptor complex. Since this supramolecular complex may also modulate immune function, measures of immunity have been examined in these lines. In the present study the immune responsiveness before and after an allogeneic priming stimulus was investigated. Lower mitogen-induced T-cell proliferation, mixed leukocyte reaction, and cytotoxic T lymphocyte activity were found in unprimed LS compared to unprimed SS mice. In contrast, the LS line exhibited a marked augmentation of these responses after priming, while the SS mice appeared unresponsive to this challenge. Addition of splenocytes or cell-free splenic cultures from primed mice to cultures from unprimed mice suggested that differences in priming-induced cell-to-cell interactions, rather than the release of a soluble helper factor(s) into the medium, are responsible for the marked augmentation of the secondary response in LS, compared to SS mice. Fewer T-helper and T-suppressor/cytotoxic cells were found in LS compared to SS mice, and this was unaffected by priming. These results extend previous findings demonstrating a higher natural killer cell activity and rate of tumor rejection in LS mice and suggest that these lines may be useful in studying the regulatory role of the GABAA complex in immune function.