Follicular dendritic cell dysfunction contributes to impaired antigen-specific humoral responses in sepsis-surviving mice.

Sepsis survivors exhibit impaired responsiveness to antigen (Ag) challenge associated with increased mortality from infection. The contribution of follicular dendritic cells (FDCs) in the impaired humoral response in sepsis-surviving mice is investigated in this study. We demonstrated that mice subjected to sepsis from cecal ligation and puncture (CLP) have reduced NP-specific high-affinity class-switched Ig antibodies compared to sham control mice following immunization with the T-dependent Ag, NP-CGG. NP-specific germinal center (GC) B cells in CLP mice exhibited reduced TNFα and AID mRNA expression compared to sham mice. CLP mice showed a reduction in FDC clusters, a reduced binding of immune complexes on FDCs, and reduced mRNA expression of CR2, ICAM-1, VCAM-1, FcγRIIB, TNFR1, IKK2 and LTbR compared to sham mice. Adoptive transfer studies showed there was no B cell-intrinsic defect. In summary, our data suggest that the reduced Ag-specific antibody response in CLP mice is secondary to a disruption in FDC and GC B cell function.