Ever wondered what happens if you remove Tfh cells from established germinal centres?

We did. We wanted to disentangle the role of Tfh cells in GC formation from their ongoing maintenance, so we used a Il21cre iDTR approach to delete Tfh cells from established GCs. Our hypothesis was that the GC would collapse, but it was surprisingly resilient.

However, Tfh cells did not come back in full numbers, which left a hole in the memory T cell pool, resulting in smaller recall germinal centres upon rechallenge.