Background: White blood cells or leukocytes, which have a variety of immunological functions, have been shown to migrate in and out of the blood stream in response to different types of stressors (Davis et al., 2008). Hence, leukocyte profiling can be used to measure stress related immune activation. In the present study we employed a psychosocial stress task to assess whether emotional arousal cause leukocyte migration. Methods: We used the Trier Social Stress Test (TSST) to induce psychosocial stress. Emotional arousal was assessed with ECG, self-report measures, and blood sampling. Results: We found an increase in heart rate from baseline throughout the TSST (p < .001) and increased blood cortisol levels directly and 30 minutes after the TSST compared to baseline (p < .001). We found an increase in total Leukocyte count after the stress task (p < .001) with a return to baseline at 30, 60 and 90 minutes after (p < .001). Conclusion: The results of our study indicate that psychosocial stress triggers a physiological response manifesting as increased heart rate, cortisol levels, and leukocyte count. Our findings suggest that emotional arousal might be a key factor in inducing an immune response under stressful conditions. It is important to note that the leukocyte count returned to baseline levels within 30 minutes following the stress task, suggesting a transient and adaptive response of the immune system to social stress. Our findings support the idea that the body's physiological and immune responses to stress are interconnected and influenced by emotional states.