Introduction Few preliminary studies suggest that night shift work is associated with a desynchronization of rhythmic immune parameters, which may explain in part the increased risk for infection, cardiometabolic disorders, and cancer in shift workers.

Objectives To examine how night shift work alters cellular immune markers.

Methods This study included 46 male rotating shift workers from a car industry in Barcelona, Spain, sampled twice toward the end of a 3-week night shift (22:00–06:00 hrs) and a 3-week day shift (06:00–14:00 hrs) rotation. We collected four blood samples per worker; before and after during each shift (night shift at 06:00 and 14:00, day shift at 22:00 and 6:00). We measured 30 cytokines, chemokines and growth factors using Luminex technology and examined within-person variations in analytes between sampling time-points and shifts. We applied linear mixed models to examine within-person associations between shift and analytes, comparing samples taken at 6:00am during each shift. We also conducted a factor analysis using analyte levels from all 4 time points for each individual to identify common factors and determine if these factors were altered by shift work.

Results We observed lower levels of several analytes during the night shift (cytokines IL17, IL12, IL4, TNFα, and cytokine receptors IL1RA, IL2R; chemokines IP10, MIP1α, MIP1β, and RANTES; growth factors GCSF, FGF, EGF, HGF, and VEGF) compared to the day shift. In the factor analysis, the main factor (explaining 57% of the variance) was negatively associated with night shift (beta: -0.14, 95%CI -0.25 to -0.03, p-value less than 0.01), indicating that night shift affects immune marker levels in this pathway. This factor included growth factors (FGF, EGF, HGF), Th1 type cytokines (IL15, IL2) and pro-inflammatory cytokines and chemokines (IL1β, MIP1α, MIP1β).

Conclusion Our results show that night shift is associated with disruption in multiple immune response pathways.