Microstress, mood, and natural killer-cell activity.

The interactions between transient minor negative and positive life events ("microstressors"), concurrent mood states, and immunological functioning were assessed by measuring levels of natural killer-cell activity (NKA), stress, and mood weekly for four weeks. No association was found between the frequency of either positive or negative microstressors and NKA, nor between concurrent mood ratings and NKA. Some individuals showed a marked and unexplained variability in NKA on a week-to-week basis. These results do not support the hypothesis that the minor stresses of everyday living affect immune function. The study does suggest that single cross-sectional determinations of NKA may not be suitable for studies of psychosocial factors and NKA.