Jchain, short for immunoglobulin joining chain, is essential for the assembly and transport of Immunoglobulin M (IgM) and Immunoglobulin A (IgA) in both humoral and mucosal immunity [1]. It binds to the tailpieces of IgM-Fc, stabilizing the IgM pentamer and bridging the interaction between IgM-Fc and the polymeric immunoglobulin receptor (pIgR), which is crucial for the function of IgM [1].

A mouse model expressing simian HBEGF (diphtheria toxin receptor, DTR) under the control of the endogenous Jchain locus (J-DTR) was developed [2]. In these mice, antibody-secreting cells (ASCs) expressed high levels of cell-surface DTR and were acutely depleted following diphtheria toxin treatment. This model allowed the tracking of ASC reconstitution following depletion in 3 distinct organs, providing a tool to study ASC biology [2].

In conclusion, Jchain is vital for the proper function of IgM in immunity. The J-DTR mouse model has been valuable in understanding the differentiation kinetics of antibody-secreting cells, contributing to the study of ASC biology. This genetic model-based research helps in revealing the role of Jchain in immune-related processes, potentially providing insights for diseases related to abnormal humoral and mucosal immunity [2].

References:

1. Li, Yaxin, Wang, Guopeng, Li, Ningning, Gao, Ning, Xiao, Junyu. 2020. Structural insights into immunoglobulin M. In Science (New York, N.Y.), 367, 1014-1017. doi:10.1126/science.aaz5425. https://pubmed.ncbi.nlm.nih.gov/32029689/

2. Pioli, KimAnh T, Ritchie, Matthew, Haq, Hira, Pioli, Peter D. 2024. Jchain-DTR Mice Allow for Diphtheria Toxin-Mediated Depletion of Antibody-Secreting Cells and Evaluation of Their Differentiation Kinetics. In bioRxiv : the preprint server for biology, , . doi:10.1101/2024.05.06.592703. https://pubmed.ncbi.nlm.nih.gov/38766257/