B cell-specific expression of B7-2 is required for follicular Th cell function in response to vaccinia virus

S Salek-Ardakani, YS Choi… - The Journal of …, 2011 - journals.aai.org
S Salek-Ardakani, YS Choi, M Rafii-El-Idrissi Benhnia, R Flynn, R Arens, S Shoenberger…
The Journal of Immunology, 2011journals.aai.org
Abstract Follicular Th (T FH) cells are specialized in provision of help to B cells that is
essential for promoting protective Ab responses. CD28/B7 (B7-1 and B7-2) interactions are
required for germinal center (GC) formation, but it is not clear if they simply support activation
of naive CD4 T cells during initiation of responses by dendritic cells or if they directly control
T FH cells and/or directly influence follicular B cell differentiation. Using a model of vaccinia
virus infection, we show that B7-2 but not B7-1 deficiency profoundly impaired T FH cell …
Abstract
Follicular Th (T FH) cells are specialized in provision of help to B cells that is essential for promoting protective Ab responses. CD28/B7 (B7-1 and B7-2) interactions are required for germinal center (GC) formation, but it is not clear if they simply support activation of naive CD4 T cells during initiation of responses by dendritic cells or if they directly control T FH cells and/or directly influence follicular B cell differentiation. Using a model of vaccinia virus infection, we show that B7-2 but not B7-1 deficiency profoundly impaired T FH cell development but did not affect CD4 T cell priming and Th1 differentiation. Consistent with this, B7-2 but not B7-1 was required for acquisition of GC B cell phenotype, plasma cell generation, and virus-specific neutralizing Ab responses. Mixed adoptive transfer experiments indicated that bidirectional interactions between CD28 expressed on activated T cells and B7-2 expressed on follicular B cells were essential for maintenance of the T FH phenotype and GC B cell development. Our data provide new insight into the source and nature of molecules required for T FH cells to direct GC B cell responses.
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