How does optimism suppress immunity? Evaluation of three affective pathways.

Studies have linked optimism to poorer immunity during difficult stressors. In this study, when 1st-year law students (N = 46) relocated to attend law school, reducing conflict among curricular and extracurricular goals, optimism predicted larger delayed-type hypersensitivity responses, indicating more robust in vivo cellular immunity. However, when students did not relocate, increasing goal conflict, optimism predicted smaller responses. Although this effect has been attributed to negative affect when difficult stressors violate optimistic expectancies, distress did not mediate optimism's effects on immunity. Alternative affective mediators related to engagement--engaged affect and fatigue--likewise failed to mediate optimism's effects, although all 3 types of affect independently influenced in vivo immunity. Alternative pathways include effort or self-regulatory depletion.