Arginine kinase (AK) is an enzyme present in various invertebrates, as well as in some trypanosomatids such as T. cruzi, the etiological agent that causes Chagas disease. In invertebrates, this protein acts as an allergen inducing an IgE-type humoral immune response. Since AK is a highly conserved protein, we decided to study whether patients with chronic Chagas disease (CCD) produce specific antibodies against T. cruzi AK (TcAK). Plasma from patients with CCD, with and without cardiac alterations and non-infected individuals were evaluated for the presence of anti-TcAK IgG and IgE antibodies by ELISA, including detection of specific IgG subclasses. Our results showed that the levels of specific anti-TcAK IgG and IgE were different between infected and non-infected individuals, but comparable between those with different clinical manifestations. Interestingly, anti-TcAK IgG4 antibodies associated with IgE-mediated allergenic processes were also increased in CCD patients. Finally, we found that several of the predicted B cell epitopes in TcAK matched allergenic peptides previously described for its homologues in other organisms. Our results revealed for the first time a parasite’s specific IgE antibody target and suggest that TcAK could contribute to delineate an inefficient B cell response by prompting a bias towards a Th2 profile. These findings also shed light on a potential allergenic response in the context of T. cruzi infection.

精氨酸激酶 (AK) 是一种存在于各种无脊椎动物以及某些锥体虫中的酶，例如克氏锥虫，它是引起南美锥虫病的病原体。在无脊椎动物中，这种蛋白质充当诱导 IgE 型体液免疫反应的过敏原。由于 AK 是一种高度保守的蛋白质，我们决定研究慢性恰加斯病 (CCD) 患者是否会产生针对克氏锥虫AK ( Tc AK)的特异性抗体。通过 ELISA评估来自 CCD 患者（有或没有心脏改变）和未感染个体的血浆中抗Tc AK IgG 和 IgE 抗体的存在，包括特定 IgG 亚类的检测。我们的结果表明，特异性抗Tc的水平AK IgG和IgE在感染者和未感染者之间存在差异，但在不同临床表现者之间具有可比性。有趣的是，与 IgE 介导的过敏过程相关的抗Tc AK IgG4 抗体在 CCD 患者中也有所增加。最后，我们发现Tc AK中的几个预测 B 细胞表位与先前描述的其他生物体中的同系物的过敏原肽相匹配。我们的结果首次揭示了寄生虫的特异性 IgE 抗体靶标，并表明Tc AK 可能通过促使对 Th2 谱的偏倚来描述低效的 B 细胞反应。这些发现还揭示了克氏锥虫的潜在过敏反应感染。