Objective Regulations and mechanisms of linalyl acetate played in the immune functions of mice were studied.

Method Thirty-two 30-d-old SPF C57BL/6 male mice were randomly divided into groups of blank control (CK) and continuous gavage of low-dose of linalyl acetate at 50 mg·kg⁻¹ (LD), medium-dose at 100 mg·kg⁻¹ (MD), or high-dose at 200 mg·kg⁻¹ (HD) for 28 d. Body weight of the mice was measured, thymus and spleen indices calculated, pathological changes of HE-stained immune organs and duodenum mucosa examined under microscope, and expressions of IgA, IgM, and IgG in the tissues analyzed by qPCR.

Result During the entire test period, no significant differences in body weight, nor any apparent growth inhibition, of the mice in the treatment groups and CK were observed (P＞0.05). The spleen indices of MD group at (0.31±0.02) and HD at (0.33±0.02) were significantly higher than that of CK at 0.26±0.01 (P＜0.05). The thymus index rose dose-dependently with no statistical significance (P＞0.05). The mice in the treatment groups displayed a clear boundary between cortex and medulla on the HE-stained thymus tissue, intact white and red pulps of the spleen, neatly arranged villi of the duodenal mucosa, no inflammatory infiltration or tissue damage, and significantly increased proportions of splenic white pulp area in the MD and HD groups (P＜0.05). In the spleens, the expressions of IgA i.e., (1.89±0.12) in MD and (2.35±0.15) in HD, IgM i.e., (1.76±0.10) in MD and (2.18±0.13) in HD and IgG i.e., (1.92±0.11) in MD and (2.41±0.14) in HD were significantly higher than those in CK (P＜0.05). And in the thymus, these genes were also upregulated in a dose-dependent manner (P＜0.05).

Conclusion Force feeding mice with linalyl acetate in the range of 50–200 mg·kg⁻¹ did not induce apparent toxicity to the animals. But the treatment promoted the development of immune-related organs and upregulated the associated globulin genes to significantly enhance the humoral immune functions of the mice. Hence, the naturally occurring ester of linalool could plausibly be used as a green immunomodulator in animal husbandry.