I investigated the response of secretory immunoglobin-A (SIg-A) to a cold pressor test (CPT). Acute physical stressors trigger the activation of the sympathetic nervous system, which may influence an immune response. Inter-individual differences in autonomic responses to acute stressors make it difficult to draw conclusions on immune system responses. My primary hypothesis was that the CPT causes an increase in SIg-A in saliva. My secondary hypothesis was that the increase in SIg-A has a direct correlation to the increase in salivary α-amylase (SαA) concentrations, cardiovascular and hemodynamic parameters indicative of sympathetic activity.
Twenty participants completed a 5-min CPT, with cardiovascular parameters measured and saliva samples collected. The effect of CPT on SIg-A had a decreasing trend that was variable in individuals. The CPT caused the SαA, HR, BP to increase (p< 0.05). There were no correlations between SIg-A and SαA concentrations, cardiovascular and hemodynamic changes during and post CPT. Our analysis showed an inverse correlation between the SIg-A magnitude of change and its baseline value (r = -0.60, p= 0.01). Therefore, the CPT increased SIg-A in participants with a low baseline and decreased SIg-A in participants with a high baseline. Our results suggest that the sympathetic nervous system does not affect the SIg-A concentrations and SIg-A changes according to its baseline in accordance with the law of initial values. These results will help interpret SIg-A studies, and to understand the interindividual variations in SIg-A responses.