Influence of Ordinary Cigarettes and Their Substitute IQOS on Secretory Immunoglobulin A in Unstimulated Saliva.

: Secretory immunoglobulin A (sIgA) plays a key role in oral and mucosal immunity, serving as a first-line defense against pathogens. Smoking is known to negatively affect immune function, but data on the impact of heated tobacco products such as IQOS on sIgA levels are limited. : To assess and compare the effects of conventional cigarette smoking and IQOS use on the concentration of salivary sIgA in healthy individuals. : A total of 200 participants were enrolled and divided into three groups: 60 non-smokers, 70 conventional cigarette smokers, and 70 IQOS users. Unstimulated whole saliva samples were collected and analyzed for sIgA concentration using ELISA method. Statistical analysis was performed using IBM SPSS Statistics 25. : Mean salivary sIgA levels were significantly lower in both cigarette smokers (246.03 μg/mL) and IQOS users (243.54 μg/mL) compared to non-smokers (380.74 μg/mL, < 0.05). No significant difference was observed between cigarette smokers and IQOS users. A pronounced reduction in sIgA was seen in female users of both tobacco products, whereas male users did not show a statistically significant decline. : Both cigarette smoking and IQOS use are associated with a significant decrease in salivary sIgA levels, particularly in females. The findings suggest that IQOS does not offer an immunological advantage over conventional smoking in terms of preserving mucosal immunity. Further studies are needed to confirm these findings and explore underlying mechanisms.