Ahl T, Reinholdt J
Department of Oral Biology, Royal Dental College Aarhus, Denmark.
Infect Immun. 1991 Feb;59(2):563-9. doi: 10.1128/iai.59.2.563-569.1991.
The mechanisms by which immunoglobulin A1 (IgA1) protease activity may enable bacteria to evade the effect of specific secretory IgA (S-IgA) antibodies are not clear. A possibility which has received indirect experimental support is that bacteria, as a consequence of the protease activity, become coated with incompetent Fab alpha fragments instead of with intact antibody molecules. Using a combination of nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting, we detected Fab alpha fragments not only on oral streptococci (Streptococcus sanguis and Streptococcus gordonii) incubated in saliva but also on the bacteria in incipient dental plaque. These results are of relevance to our previous observation that IgA1 protease activity may neutralize the ability of S-IgA antibodies to inhibit the adherence of oral streptococci to saliva-coated hydroxyapatite.
免疫球蛋白A1（IgA1）蛋白酶活性使细菌能够逃避特异性分泌型IgA（S-IgA）抗体作用的机制尚不清楚。一个得到间接实验支持的可能性是，由于蛋白酶活性，细菌表面覆盖的是无功能的Fabα片段而非完整的抗体分子。通过非还原十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和免疫印迹相结合的方法，我们不仅在唾液中孵育的口腔链球菌（血链球菌和戈登链球菌）上检测到了Fabα片段，还在早期牙菌斑中的细菌上检测到了该片段。这些结果与我们之前的观察结果相关，即IgA1蛋白酶活性可能会中和S-IgA抗体抑制口腔链球菌黏附于唾液包被的羟基磷灰石的能力。
