Hillyer Julián F, Christensen Bruce M
Department of Animal Health & Biomedical Sciences, University of Wisconsin-Madison, WI 53706, USA.
J Histochem Cytochem. 2005 Jun;53(6):689-98. doi: 10.1369/jhc.4A6564.2005.
Mosquitoes mount strong humoral and cellular immune responses against foreign organisms. Two components of the mosquito immune response that have received much attention are the phenoloxidase cascade that leads to melanization and antimicrobial peptides. The purpose of the current study was to use immunocytochemistry and transmission electron microscopy to identify the location of the melanization rate-limiting enzyme phenoloxidase and the antimicrobial peptide defensin in innate immune reactions against Escherichia coli and Micrococcus luteus by the mosquito Aedes aegypti. Our results show that both phenoloxidase and defensin are present at the sites of melanin biosynthesis in immune reactions against bacteria. Furthermore, both proteins are often present inside the same melanotic capsules. When hemocytes were analyzed, phenoloxidase was present in the cytosol of oenocytoids, but no significant amounts of defensin were detected inside any hemocytes. In summary, these data show that phenoloxidase and defensin colocalize in melanization reactions against bacteria and argue for further studies into the potential role of defensin in phenoloxidase-based melanization innate immune responses in mosquitoes.
蚊子会针对外来生物体产生强烈的体液免疫和细胞免疫反应。蚊子免疫反应中备受关注的两个组成部分是导致黑化的酚氧化酶级联反应和抗菌肽。本研究的目的是利用免疫细胞化学和透射电子显微镜，确定埃及伊蚊在针对大肠杆菌和藤黄微球菌的先天免疫反应中，黑化限速酶酚氧化酶和抗菌肽防御素的定位。我们的结果表明，在针对细菌的免疫反应中，酚氧化酶和防御素都存在于黑色素生物合成的部位。此外，这两种蛋白质常常存在于同一个黑化包囊内。当分析血细胞时，酚氧化酶存在于oenocytoids的细胞质中，但在任何血细胞内均未检测到大量的防御素。总之，这些数据表明酚氧化酶和防御素在针对细菌的黑化反应中共定位，并支持进一步研究防御素在蚊子基于酚氧化酶的黑化先天免疫反应中的潜在作用。
