Germinal center responses at barrier organ sites

In this review, we detail the features of barrier germinal centers (GC) that form in tertiary lymphoid structures (TLSs) within non-immune organs that host a local microbiome, and posit a framework of immunity where TLS-GCs created at barrier sites are a key part of normal humoral immunity, and that they form the first layer of an intended multi-layered and increasingly defensive adaptive immune system, providing complementary tissue-specific responses, alongside the local secondary lymphoid organ network and systemic immune responses.