Paltrinieri Saverio, Ceciliani Fabrizio, Gabanti Elisa, Sironi Giuseppe, Giordano Alessia, Addie Diane
1Università di Milano, Milan.
4Dipartimento di Patologia Animale, Igiene e Sanità Pubblica Veterinaria Università di Milano, Via Celoria 10, I20133 Milano, Italy.
Comp Clin Path. 2003;12(3):140-146. doi: 10.1007/s00580-003-0489-8.
α-Acid glycoprotein (AGP) is an acute-phase protein (APP) that modulates immune responses, probably - at least in humans - owing to the modification of its glycosylation pattern. On this perspective, feline AGP can be a useful comparative model, as it has different concentrations in cats susceptible or resistant to some disease. As a preliminary approach to the study of feline AGP (fAGP) we have purified this protein from feline serum by HPLC using human AGP (hAGP) as a model. Immunoblotting with a polyclonal antibody against fAGP and with a monoclonal antibody against hAGP was performed on serum from healthy cats, from cats exposed to feline coronavirus (FCoV) infection and from cats with purulent inflammations, such as feline infectious peritonitis (FIP), feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV). Immunohistochemistry on tissues from healthy cats and from cats with different diseases (FIP, FIV, FeLV, locally extensive inflammation) was also performed with the same antibodies. Both hAGP and fAGP have been purified to homogenity as determined by SDS-PAGE. fAGP did not react with the anti-hAGP antibody which, in contrast, detected in feline serum a low MW protein that we called fAGP-related protein (fAGPrP). This protein was underexpressed in cats with FeLV and FIP. Both fAGP and fAGPrP were immunohistochemically detected in plasma and hepatocytes with a stronger intensity in cats with FIP and some inflammatory conditions. Moreover, fAGPrP was detected in the cytoplasm of tissue cells, most likely identifiable with plasma cells. These cells were rarely detectable in cats with FIV and FeLV, and numerous in cats with FIP and with locally extensive inflammation. In conclusion, purified fAGP has physicochemical characteristics similar to those of hAGP, but does not cross-react with anti-hAGP antibodies. In contrast, the anti-hAGP detected an AGP-related protein whose blood concentration and tissue distribution was not related to that of fAGP. Moreover, both fAGP and fAGPrP were differently expressed in cats with pathologic conditions compared to controls. Further study of these proteins by analysing their structural characteristics is required.
α-酸性糖蛋白（AGP）是一种急性期蛋白（APP），它可调节免疫反应，可能至少在人类中，是由于其糖基化模式的改变。从这个角度来看，猫AGP可能是一个有用的比较模型，因为它在对某些疾病易感或有抵抗力的猫中浓度不同。作为研究猫AGP（fAGP）的初步方法，我们以人AGP（hAGP）为模型，通过高效液相色谱法从猫血清中纯化了这种蛋白质。用抗fAGP的多克隆抗体和抗hAGP的单克隆抗体对健康猫、暴露于猫冠状病毒（FCoV）感染的猫以及患有化脓性炎症（如猫传染性腹膜炎（FIP）、猫免疫缺陷病毒（FIV）和猫白血病病毒（FeLV））的猫的血清进行免疫印迹分析。还用相同的抗体对健康猫和患有不同疾病（FIP、FIV、FeLV、局部广泛炎症）的猫的组织进行免疫组织化学分析。通过SDS-PAGE测定，hAGP和fAGP均已纯化至均一性。fAGP与抗hAGP抗体不发生反应，相反，该抗体在猫血清中检测到一种低分子量蛋白质，我们称之为fAGP相关蛋白（fAGPrP）。这种蛋白质在患有FeLV和FIP的猫中表达不足。fAGP和fAGPrP在血浆和肝细胞中均通过免疫组织化学检测到，在患有FIP和某些炎症的猫中强度更强。此外，fAGPrP在组织细胞的细胞质中被检测到，很可能是浆细胞。这些细胞在患有FIV和FeLV的猫中很少能检测到，而在患有FIP和局部广泛炎症的猫中大量存在。总之，纯化的fAGP具有与hAGP相似的物理化学特性，但不与抗hAGP抗体发生交叉反应。相反，抗hAGP检测到一种AGP相关蛋白，其血液浓度和组织分布与fAGP无关。此外，与对照组相比，fAGP和fAGPrP在患有病理状况的猫中表达不同。需要通过分析其结构特征对这些蛋白质进行进一步研究。
