Differential immune responses of immunoglobulin Z subclass members in antibacterial immunity in a zebrafish model.
Jian-Fei Ji, Chong-Bin Hu, Tong Shao, Dong-Dong Fan, Nan Zhang, Ai-Fu Lin, Li-Xin Xiang, Jian-Zhong Shao
Author Information
Jian-Fei Ji: College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China.
Chong-Bin Hu: College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China.
Tong Shao: College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China.
Dong-Dong Fan: College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China.
Nan Zhang: College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China.
Ai-Fu Lin: College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China.
Li-Xin Xiang: College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China.
Jian-Zhong Shao: College of Life Sciences, Key Laboratory for Cell and Gene Engineering of Zhejiang Province, Zhejiang University, Hangzhou, China. ORCID
Immunoglobulin Z (IgZ) or its equivalent immunoglobulin T (IgT) is a newly identified immunoglobulin (Ig) class from teleost fish. This Ig class is characterized by its involvement in mucosa-associated lymphoid tissues (MALTs) for mucosal defence against pathogen infection. Recently, several subclass members of IgZ/IgT, such as IgZ, IgZ2, Igτ1, Igτ2 and Igτ3, have been further identified from zebrafish, common carp and rainbow trout. However, the functional diversity and correlation among these subclasses remain uncertain. Here, we explored the differential immune reactions of the IgZ and IgZ2 subclasses in antibacterial immunity in a zebrafish model. IgZ was extensively distributed in the peripheral serum and skin/gill MALTs and showed a rapid induction upon bacterial infection. IgZ2 was specialized in skin/gill MALTs and showed a strong induction following IgZ production. Correspondingly, the IgZ B cells had a wider distribution in the systemic primary/secondary lymphoid tissues and MALTs than the IgZ2 B cells, which were predominant in MALTs. IgZ and IgZ2 exhibited a complementary effect in antibacterial immunity by possessing differential abilities. That is, IgZ is preferentially involved in bactericidal reaction that is in part C1q-dependent, and IgZ2 participates in neutralization action through bacteria-coating activity. The production of IgZ largely depended on the αβ T/CD4 T cells, whereas that of IgZ2 did not, suggesting the different dependencies of IgZ and IgZ2 on systemic immunity. Our findings demonstrate that the functional behaviour and mechanism of the IgZ/IgT family are more diverse than previously recognized and thus improve the current knowledge about this ancient Ig class.
