To assess the value of immunohistochemical analysis for expressions of C3d, C4d, IgG, IgG4, and CD123 in the diagnosis of autoimmune skin diseases. Methods: We investigated the expressions of C3d, C4d, IgG, IgG4, and CD123 in paraffin-embedded, formalin-fixed tissues from 27 lupus erythematosus cases, including 8 discoid lupus erythematosus (DLE) cases, 4 subacute cutaneous lupus erythematosus (SCLE) cases, and 15 systemic lupus erythematosus (SLE) cases. Tissues from 15 dermatomyositis (DM) cases, 15 bullous pemphigoid (BP) cases, and 15 pemphigus cases were examined by immunohistochemical analysis. The differences in expression rates of C3d, C4d, IgG, IgG4, and CD123 between immunohistochemical staining and direct immunofluorescence were compared in the diagnosis of these diseases. Results: In the lupus erythematosus group, the positive rates of C3d and C4d deposited along the dermoepidermal junction were 85.2% and 51.9%, respectively. In the dermatomyositis group, the positive rates of C3d and C4d deposited along the dermoepidermal junction were 40% and 0, respectively. The expressions of C3d and C4d in lupus erythematosus tissues were significantly higher than those in DM tissues (P<0.05). The expression of CD123 protein in skin lesions of the lupus group was significantly higher than that in the DM group (P<0.05). In the BP group, the positive rates of C3d and C4d deposited along the dermoepidermal junction were 100% and 86.7%, respectively. In the pemphigus group, the positive rates of C3d and C4d deposited in the intercellular space of keratinocytes were 100% and 60%, respectively. The expressions of IgG and IgG4 in pemphigus tissues were higher than those in BP tissues (P<0.05). And the ratios of IgG4 to IgG in the pemphigus group was significantly higher than that in the BP group (P<0.05). Conclusion: The assays of C3d and C4d define an important diagnostic adjunct in evaluation of lupus erythematosus, BP and pemphigus. In some cases, it may even replace the direct immunofluorescence as a diagnostic adjunct. The expression of CD123 possesses certain clinical significance for the differential diagnosis of lupus erythematosus, and IgG4 and IgG expressions have adjunctive diagnostic significance for pemphigus.
目的：探讨免疫组织化学方法检测皮损组织中C3d，C4d，IgG，IgG4及CD123表达在诊断自身免疫性皮肤病中的应用价值。方法：采用免疫组织化学方法检测27例红斑狼疮(其中8例盘状红斑狼疮、4例亚急性皮肤型红斑狼疮、15例系统性红斑狼疮)、15例皮肌炎、15例大疱性类天疱疮、15例天疱疮皮损组织石蜡切片中的C3d，C4d，IgG，IgG4及CD123表达情况；比较免疫组织化学染色与直接免疫荧光检测在红斑狼疮、大疱性类天疱疮、天疱疮皮损组织中上述5种抗体的阳性率。结果：红斑狼疮组皮损基底膜带的C3d，C4d阳性率分别为85.2%，51.9%，皮肌炎组C3d，C4d阳性率分别为40%，0；红斑狼疮组皮损组织中C3d，C4d表达水平均明显高于皮肌炎组(P<0.05)。红斑狼疮组皮损组织中CD123蛋白的表达水平显著高于皮肌炎组(P<0.05)。大疱性类天疱疮组皮损基底膜带的C3d，C4d阳性率分别为100%，86.7%，天疱疮组角质形成细胞间的C3d，C4d阳性率分别为100%，60%。天疱疮组皮损真皮内的IgG，IgG4表达水平明显高于大疱性类天疱疮组(P<0.05)，且天疱疮组IgG4/IgG明显高于大疱性类天疱疮组(P<0.05)。结论：免疫组织化学检测皮损组织中的C3d，C4d在红斑狼疮、大疱性类天疱疮和天疱疮中有重要的诊断价值，在某些情况下可能作为替代直接免疫荧光的诊断工具。CD123表达对于红斑狼疮的鉴别诊断有一定的临床意义，IgG4和IgG对于天疱疮有辅助诊断意义。.