The effects of storage time and temperature on recovery of salivary secretory immunoglobulin A.

OBJECTIVES: This study aimed to determine the optimal storage temperature to minimise degradation of salivary s-IgA for field-based surveillance applications in resource-limited settings. METHODS: Saliva samples from 40 Zambian adults were stored at +25°C, +4°C, -20°C, and -80°C and each tested by ELISA for salivary s-IgA concentration at 0, 1, 2, 7, and 15 days. Differences were determined among concentrations over time and temperature compared with baseline values. Kruskal-Wallis tests were applied to analyse variance. Single and multivariate regression analyses estimated the influence of storage time and temperature on recoverable s-IgA. RESULTS: Results revealed a statistically significant decrease in salivary s-IgA concentration as storage time increased and as temperature decreased. Degradation during storage time was most pronounced at lower temperatures. CONCLUSIONS: s-IgA is stable at ambient temperatures in Zambia for at least 15 days, suggesting no need for cold chain handling before analysis in field-based surveillance applications.