Expression of mast cell tryptase and immunoglobulin E is increased in cutaneous photodamage: implications for carcinogenesis

<b>Purpose:</b> Mast cells, their serine proteinase tryptase, and immunoglobulin E (IgE) can be involved in cutaneous carcinogenesis. <b>Materials and methods:</b> To study the association of tryptase⁺ and IgE⁺ cells with photodamage and skin cancers 385 adult patients (201 males, 184 females, 75 with immunosuppression) at risk of any type of skin cancer were examined. Skin biopsies were taken from the sun-protected medial arm and from the photodamaged dorsal forearm skin followed by immunohistochemical staining for tryptase and IgE. <b>Results:</b> The results show that tryptase⁺ and IgE⁺ cells are significantly higher in number in the photodamaged than sun-protected skin, both in immunocompetent and -compromised subjects, and there is a strong correlation between tryptase⁺ and IgE⁺ cells. The numbers of forearm tryptase⁺ and especially IgE⁺ cells associated significantly with the forearm photodamage severity. In the logistic regression analysis, the forearm to upper arm ratio of IgE⁺ cells produced a univariate odds ratio of 1.521 (<i>p</i> = .010) and a multivariate one of 3.875 (<i>p</i> = .047) for the history of squamous cell carcinoma. The serum level of total IgE correlated significantly to the IgE to tryptase ratio in both skin sites. <b>Conclusions:</b> Therefore, IgE⁺ mast cells participate in photodamage and carcinogenesis, though it is unclear whether they are tumor-protective or -causative.

**研究目的：** 肥大细胞、其丝氨酸蛋白酶（serine proteinase）类胰蛋白酶（tryptase）以及免疫球蛋白E（IgE）可参与皮肤癌变过程。
**材料与方法：** 为探究类胰蛋白酶阳性与IgE阳性细胞与光损伤及皮肤癌的关联，本研究纳入385名存在各类皮肤癌患病风险的成年受试者（其中男性201例、女性184例，75例存在免疫抑制状态）并接受检查。研究人员分别从防晒的上臂内侧以及存在光损伤的前臂背侧皮肤采集皮肤活检样本，随后对样本开展类胰蛋白酶与IgE的免疫组织化学染色。
**研究结果：** 结果显示，无论免疫功能正常还是受损的受试者，光损伤皮肤内的类胰蛋白酶阳性与IgE阳性细胞数量均显著高于防晒皮肤；且类胰蛋白酶阳性细胞与IgE阳性细胞之间存在强相关性。前臂组织内的类胰蛋白酶阳性细胞，尤其是IgE阳性细胞的数量，与前臂光损伤严重程度呈显著相关。经logistic回归分析，IgE阳性细胞的前臂/上臂比值对鳞状细胞癌（squamous cell carcinoma）病史的单变量优势比为1.521（*p*=0.010），多变量优势比为3.875（*p*=0.047）。总IgE血清水平在两处皮肤位点均与IgE与类胰蛋白酶的比值呈显著相关。
**研究结论：** 综上，IgE阳性肥大细胞参与了光损伤与癌变过程，但其究竟是发挥肿瘤防护还是致癌作用，目前尚不明确。