Introduction to the special issue: A festschrift for Janice Kiecolt-Glaser - At the origin of stress and immunity.

This special issue of pays tribute to Janice Kiecolt-Glaser's groundbreaking career and marks her well-earned retirement. As a leader in human psychoneuroimmunology (PNI), Kiecolt-Glaser transformed the domain by showing that everyday stressors, along with significant life events, can significantly affect the immune system. Her groundbreaking research on informal dementia caregivers revealed the detrimental effects of chronic psychological stress, including delayed wound healing, virus reactivation, heightened proinflammatory cytokine levels, and weakened vaccine responses. This issue features contributions from her former mentees and collaborators, reflecting the enduring influence of her mentorship and research. Few psychologists in PNI have matched her mentorship legacy, and the included works showcase the ways her guidance has shaped their scientific careers. These articles explore new frameworks for integrating affective science with immune health, interventions designed for couples managing chronic illness, and studies examining the immune consequences of relational dynamics. Personal reflections from her trainees and collaborators highlight Kiecolt-Glaser's unique ability to balance rigorous expectations with unwavering support, fostering their professional growth. Collectively, this special issue illustrates how Kiecolt-Glaser's scholarship continues to advance the field, pushing the boundaries of interdisciplinary inquiry. Her influence on the next generation of scientists ensures that her legacy will remain central to PNI, reinforcing the critical role of relationships in health and disease.