五氯酚 (PCP)是一種強效的殺菌劑，被廣泛的當作木材防腐劑使用，主要的代謝產物為四氯對苯二酚(TCHQ)。皮膚暴露是五氯酚進入人體的一項重要的途徑。五氯酚被認為能影響人體、小鼠及大鼠的免疫功能。人類發生惡性淋巴瘤及白血病被認為與職業暴露五氯酚有關。研究指出，小鼠皮膚暴露五氯酚會誘發淋巴癌生成。然而，詳細的機制仍然是不清楚的。 因此，本研究透過皮膚暴露的模式，探討五氯酚及其代謝產物四氯對苯二酚對小鼠脾臟免疫功能的影響。研究結果指出，不論是動物實驗或是細胞實驗，五氯酚及四氯對苯二酚都會影響脾臟細胞的免疫功能。動物實驗發現，小鼠暴露五氯酚六週，會有脾臟的重量、細胞週期S phase 及刺激原誘發的細胞增生的現象。而暴露五氯酚十二週的小鼠，脾臟重量減少，凋亡的細胞數增加，細胞內毒素(Lipoplysaccharide, LPS)誘發的細胞增生能力也被抑制。脾臟細胞在體外培養的過程中會自發性的走向細胞凋亡，但是處理四氯對苯二酚的脾臟細胞，細胞凋亡被抑制下來。並且, 將脾臟細胞先處理四氯對苯二酚後，細胞的增生作用及分泌細胞激素-IL-2和TNF-α的能力也都會受到抑制。不受控制的細胞增生以及細胞凋亡的抑制可能與細胞的癌化有關。由研究結果，五氯酚及四氯對苯二酚造成的脾臟細胞異常，可能是五氯酚誘發小鼠淋巴癌生成的一項可能的機制，但是完整詳細的機制仍需要進一步研究。

　Pentachlorophenol (PCP) is a general biocide used extensively as a wood preservative. The major metabolite of PCP is tetrachlorohydroquinone (TCHQ). Dermal absorption is an important route PCP in human. PCP has been evaluated for effects on immune function in human, mice and rats. In human, malignant lymphoma and leukemia have been associated with occupational exposure. Lymphoma was induced in mice by dermal exposure of PCP. However, the precise mechanism is still unclear. Thereby, this study was designed to investigate the effects of PCP and TCHQ on immune system, particularly spleen in mice by dermal exposure. The result indicated that PCP and TCHQ affect splenpcytes and its immune function both in vivo and in vitro. In vivo, mice treated with PCP for 6 wks had increased spleen weight, S phase of splenpcytes and mitogen-induced cell proliferation. Mice treated with PCP for 12 wks decrease spleen weight, increased apoptotic splenocytes and inhibited LPS-induced proliferation. Spontaneous apoptosis was found in normal primary culture of splenocytes. We found a significant inhibition of apoptosis in culture splenocytes treated with TCHQ. Whereas, pretreatment of TCHQ inhibited splenocytes proliferation and secreted cytokines, including IL-2 and TNF-αstimulated by mitogen. Uncontrolled cell proliferation and inhibition of apoptosis in cells could be associated with the process of carcinogenesis. We suggest that malfunction of splenocytes induced by PCP and TCHQ could be one of the possible mechanisms of PCP-induced lymphoma in mice. Nevertheless, the detail mechanisms need to be further investigated.

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