Morphine modulates γδ lymphocytes cytolytic activity following BCG vaccination

Chronic opioid administration modulates lymphocytes’ functional capabilities increasing susceptibility to infectious diseases. Bacille-Calmette-Guérin (BCG) vaccination initiates a non-specific and specific cell-mediated immunity orchestrated by T lymphocytes including γδ T lymphocytes. γδ T lymphocytes increase in natural killer and antigen-directed cytolytic response following BCG vaccination. The objective of this study was to determine morphine effects on γδ T lymphocytes’ cytolytic activity. Pigs were chronically administered morphine and subsequently vaccinated with Mycobacterium bovis BCG. By administering morphine prior to BCG vaccination, natural killer response was significantly suppressed (p = .034). Furthermore, innate cytolytic response against M. bovis-infected monocytes (p = .002) as well as antigen specific cytolytic functions (p = .04) were significantly altered due to morphine administration. It was concluded that administering morphine prior to BCG vaccination significantly altered γδ T lymphocyte cytolytic responses.