Immunoglobulin (Ig) A is the most abundant antibody isotype present at mucosal surfaces and the second most abundant in human serum. In addition to preventing pathogen entry at mucosal surfaces, IgA can control and eradicate bacterial and viral infections through a variety of antibody-mediated innate effector cell mechanisms. The role of mucosal IgA in infection (e.g. neutralization) and in inflammatory homeostasis (e.g. allergy and autoimmunity) has been extensively investigated; by contrast, serum IgA is comparatively understudied. IgA binding to fragment crystallizable alpha receptor plays a dual role in the activation and inhibition of innate effector cell functions. Mounting evidence suggests that serum IgA induces potent effector functions against various bacterial and some viral infections including Neisseria meningitidis and rotavirus. Furthermore, in the era of immunotherapy, serum IgA provides an interesting alternative to classical IgG monoclonal antibodies to treat cancer and infectious pathogens. Here we discuss the role of serum IgA in infectious diseases with reference to bacterial and viral infections and the potential for IgA as a monoclonal antibody therapy.

中文翻译：

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血清IgA Fc效应子在传染病和癌症中起作用。

免疫球蛋白（Ig）A是粘膜表面上含量最高的抗体同种型，在人血清中含量第二高。除了防止病原体进入粘膜表面外，IgA还可以通过多种抗体介导的先天效应细胞机制控制和根除细菌和病毒感染。粘膜IgA在感染（例如中和）和炎症稳态（例如过敏和自身免疫）中的作用已得到广泛研究；相比之下，血清IgA的研究相对较少。与片段可结晶的α受体结合的IgA在激活和抑制先天性效应细胞功能中起双重作用。越来越多的证据表明，血清IgA可以诱导针对各种细菌和某些病毒感染（包括脑膜炎奈瑟氏菌和轮状病毒）的有效效应子功能。此外，在免疫治疗时代，血清IgA提供了一种替代经典IgG单克隆抗体的有趣替代品，可用于治疗癌症和传染性病原体。在这里，我们讨论细菌和病毒感染时血清IgA在传染病中的作用，以及将IgA作为单克隆抗体疗法的潜​​力。