Positive selection of IgG over IgM plasma cells through BCR isotype-specific antigen presentation and signaling.

IgG1-expressing plasma cells outcompete IgM cells by enhanced antigen presentation and signaling, leading to greater bone marrow longevity and immune response efficiency.

• Why it matters: Understanding how B cell isotype switching influences plasma cell survival and function is crucial for improving vaccine design and immune therapies, yet the mechanisms remain poorly defined.
• What they did: The study examined germinal center B cells and plasma cells, revealing that IgG1 BCRs promote higher antigen presentation to T follicular helper cells and reduce apoptosis via BCR signaling, with over 100 IgG1 PCs compared to IgM.
• The result: Findings demonstrate that isotype-specific antigen presentation and signaling biases favor IgG1 plasma cell survival and migration to the bone marrow, enhancing long-term humoral immunity.