Animal Health Research Center (CISA-INIA), Madrid, Spain.
Front Immunol. 2019 Dec 17;10:2902. doi: 10.3389/fimmu.2019.02902. eCollection 2019.
In the absence of class switch recombination and germinal centers, the mechanisms through which B cells from teleost fish mount extrafollicular immunoglobulin M (IgM) memory responses remains mostly unexplored. In this report, we demonstrate that teleost IgM B cells respond to CD40L, a thymus-dependent activation signal, similarly to mammalian B2 cells. However, when stimulated with different types of antigens, fish IgM B cells only reach a general activation state in response to antigens cataloged as thymus-independent 1 (TI-1) in mammals, as established through both functional assays and RNA sequencing. Interestingly, fish IgM B cells remained completely unresponsive to TI-2 antigens, suggesting that the engagement of innate receptors provided by TI-1 antigens is required for the activation of teleost B cells. Finally, a synergy between CD40L and TI-1 antigens was also demonstrated, further supporting that there is no clear dichotomy between thymus-dependent and TI responses in teleost fish.
在没有类别转换重组和生发中心的情况下，研究硬骨鱼类 B 细胞如何产生滤泡外免疫球蛋白 M（IgM）记忆应答的机制在很大程度上仍未得到探索。在本报告中，我们证明了硬骨鱼 IgM B 细胞对 CD40L（一种依赖于胸腺的激活信号）的反应类似于哺乳动物 B2 细胞。然而，当用不同类型的抗原刺激时，鱼类 IgM B 细胞仅对被归类为哺乳动物中的非依赖性 1（TI-1）的抗原做出一般性的激活反应，这是通过功能测定和 RNA 测序确定的。有趣的是，鱼类 IgM B 细胞对 TI-2 抗原完全没有反应，这表明 TI-1 抗原提供的先天受体的参与对于硬骨鱼 B 细胞的激活是必需的。最后，还证明了 CD40L 和 TI-1 抗原之间存在协同作用，这进一步支持了在硬骨鱼中不存在明显的依赖于胸腺和 TI 反应之间的二分法。
