甲殼素 (chitosan) 為D型葡萄糖胺 (D-glucosamine) 聚合而成的多醣，存在於甲殼類生物的外殼中。研究指出，甲殼素具有多種生理活性，包含抗微生物以及抗腫瘤等活性，但其免疫調節功能，仍無完整研究，因此本篇主要研究目的在探討蟹殼甲殼素對BALB/c小鼠脾臟細胞增生以及細胞激素分泌的影響。將不同濃度蟹殼甲殼素樣品與小鼠脾臟細胞共同培養72小時，再以3-(4,5-dimethylthiazol-2,5-diphenyl)-tetrazoliumbromide (MTT) 測定細胞增生；另外，將不同濃度的蟹殼甲殼素與小鼠脾臟細胞共同培養48小時，取其上清液，測定細胞激素分泌量。結果顯示，蟹殼甲殼素在濃度156~1250 μg/mL時有顯著刺激脾臟細胞增生之趨勢。細胞激素分泌量顯示，單獨添加蟹殼甲殼素，在濃度20~1250 μg/mL範圍內，對小鼠脾臟細胞介白質
(interleukin, IL)-4及IL-6的分泌量無顯著影響。脾臟細胞在內毒素脂多醣(lipopolysaccharide, LPS) 刺激下，添加適當劑量蟹殼甲殼素時，顯著刺激細胞激素IL-2分泌；添加蟹殼甲殼素濃度為20~1250 μg/mL時，能顯著抑制細胞激素IL-6以及IL-10分泌量；分析IL-6 (促發炎細胞激素) / IL-10 (抗發炎細胞激素) 分泌量比值，顯示添加適當劑量蟹殼甲殼素時，IL-6/IL-10的比值有下降的趨勢，推測在此濃度範圍內，甲殼素可能有降低發炎之潛力。綜合本試驗結果發現，適量添加蟹殼甲殼素，能刺激小鼠初代脾臟細胞增生、IL-2分泌，並調節在LPS誘發發炎狀況下，降低促發炎/抗發炎細胞激素分泌量比值，具有抗發炎潛力。

Chitosan, found in the exoskeleton of crustacean, is a D-glucosamine-polymerized polysaccharide. Some studies have indicated that chitosan has multiple physiological functions, including antimicrobial and antitumor
activities. However, the report on immunomodulatory effects of chitosan is still limited. This study attempted to investigate the effects of crab shell’s chitosan on the proliferation and cytokine secretions of
primary spleen cells from female BALB/c mice. Different concentrations (range from 5 μg/mL to 1250 μg/mL) of crab shell’s chitosan were administered to splenocyte cultures for 72 h and 48 h, respectively, in order to assay the cell proliferation and cytokine secretion levels. The splenocyte proliferation was determined using a3-(4,5-dimethylthiazol-2,5-diphenyl)-tetrazolium bromide (MTT) method. The cytokine secretion levels were assessed using an ELISA. The results showed that crab shell’s chitosan administration (range from 156 μg/mL to 1250 μg/mL) significantly (p < 0.05) increased the splenocyte proliferation. Although crab shell’s chitosan administration alone did not significantly affect secretion levels of interleukin (IL)-4 and IL-6 in primary splenocyte cultures, crab shell’s chitosan administration at moderate concentrations significantly increased IL-2 levels secreted by lipopolysaccharide (LPS)-stimulated splenocytes. Crab shell’s chitosan administration also markedly inhibited both IL-6 and IL-10 levels produced by LPS-stimulated splenocytes. Further assay indicated that crab shell’s chitosan administration at moderate concentrations slightly diminished IL-6 (proinflammatory cytokine)/IL-10 (anti-inflammatory cytokine) secretion ratios, suggesting that crab shell’s chitosan might have anti-inflammatory effects in vitro. In conclusion, crab shell’s chitosan administration at moderate concentrations demonstrated immunostimulatory effects including the stimulation on splenocyte proliferation and IL-2 secretion. The results from this study also suggest that crab shell’s chitosan might have anti-inflammatory potential via slightly inhibiting the secretion ratio of IL-6/IL-10.