DNA疫苗引发局部肌肉组织DCs、CD4+T细胞的聚集浸润

目的 观察在注射DNA疫苗后的不同时间段内，肌肉注射部位细胞的聚集情况，并对细胞表型进行检测，为阐述DNA疫苗激活机体免疫反应机制提供直接的组织学证据。方法 分别于DNA注射小鼠后6h、12h、1d、2d、3d、4d、5d、6d切取注射部位肌肉组织，HE染色观察细胞聚集情况；LSAB法检测聚集细胞CD205、CD4及CD8分子的表达。结果 疫苗注射后6h～6d，在肌肉组织间隙中发现有不同程度的细胞浸润，早期主要以巨噬细胞样细胞和淋巴细胞为主，晚期巨噬细胞样细胞占优势。在疫苗注射后24h的肌肉组织中有少量的CD205阳性细胞，第3d时数量稍多，其余时间段CD205染色均为阴性。对浸润的淋巴细胞的亚型进行鉴定发现，在6h～6d的肌肉切片中只检测到CD4^ T细胞，未发现CD8^ T细胞的细胞。结论 DNA疫苗免疫注射引发的细胞浸润与一般的炎症反应不同，有其特有的特征。DCs、CD4^ T细胞参与DNA免疫并可能起着重要的作用；DNA免疫激活的CTL发挥免疫效应可能不在肌肉组织。

Infiltration of DCs and CD4+ T Cells in Muscle after DNA Immunization

Objective In order to get a better understanding of the mechanism of DNA initiating specific cytotoxicity T lymphocyte(CTL) immune response, we observed the local infiltration in injection site at different time after DNA immunization and further studied the characters of infiltration cells. Methods The local infiltration in injection sites was observed by HE staining at 6 h, 12 h and 1-6 days after DNA immunization. Infiltration cells were further studied with the mice dendritic cells marker CD205, T lymphocyte marker CD4 and CD8 by immunohistological methods. Results phAFP injection into mouse muscle led to a local infiltration. Infiltrates reached peak at 3-6 days after injection and appeared in several discrete clusters within the muscles. The predominant cell types found in infiltrates were macrophage-like cells and lymphocytes. Immunohistological staining revealed CD205~ and CD4~ cells. CD4~ cells could be detected in any of the injected muscles. CD205~ cells were only seen at 24 h to day 3, appearing later and disappearing earlier than CD4~ cells. However, CD8~ immunostaining positivity could not be found. Conclusion Our findings indicate that the character of local infiltration after DNA immunization is different from the inflammation of injection. The recruitment of CD205~ to the injection site suggests that DCs and Th cells play an important role in DNA immunization.