Bee pollen is a valuable apitherapeutic product and has been known to have diverse biological activities, including antimicrobial, anti-inflammatory, and even anticancer activity. However, its effect on the immune system is not well studied and is rather controversial. This study intended to elucidate the biological activity of bee pollen on immunity. For this purpose, we used lyophilized bee pollen after wet grinding, which shows increased extraction of bioactive components and enhanced biological activity. First, lyophilized bee pollen after wet grinding significantly increased the proliferation of splenocytes isolated from normal mice. On the other hand, lyophilized bee pollen after wet grinding dose-dependently reversed splenocyte proliferation by concanavalin A or lipopolysaccharide. To clarify the activity of bee pollen on immunity lyophilized bee pollen after wet grinding was administered daily to mice for five weeks and isolated splenocytes. In this study, there was no significant difference in the population of immune cells and the size of spleen between bee pollen- and sterile water-treated groups. However, proliferation of splenocyte isolated from bee pollen-administered animals was boosted by both concanavalin A and lipopolysaccharide. Finally, kaempferol, a well-known flavonoid from bee pollen, dose-dependently increased splenocyte proliferation by both Con A and LPS. On the other hand, naringenin, another flavonoid in the bee pollen, dose-dependently inhibited the proliferation of splenocytes by Con A and LPS. Together, these data indicate that bee pollen may be able to prime the immunity to boost immune reaction after inflammation.

1. Introduction
2. Research methods
    2.1. Animals
    2.2. Splenocyte isolation and proliferationassay
    2.3. Splenocyte proliferation by bee pollen
    2.4. Splenocyte proliferation by chronicadministration of bee pollen in mice
    2.5. Splenocyte proliferation by flavonoids
    2.6. Statistical Analysis
3. Results and Discussion
    3.1. Proliferation of splenocytes by beepollen
    3.2. Effect of bee pollen on proliferationof splenocytes induced by mitogens
    3.3. Effect of bee pollen when chronicallyadministered to mice
    3.4. Effect of flavonoids on splenocytesproliferation
    3.5. Discussion
4. Conclusion
Acknowledgments

• Jia Bak(Department of Pharmaceutical Science and Technology, Kyungsung University, Busan 48434, Republic of Korea)
• Il Kyung Chung(Department of Biotechnology, Daegu Catholic University, Kyeongsan-Si, Gyeongbuk, 38430, Republic of Korea)
• Yun-Sik Choi(Department of Pharmacology, College of Pharmacy, Kyungsung University, Busan 48434, Republic of Korea) Corresponding author