Hey Daniel, you might find this recent paper interesting! They discuss autonomous assembly of ectopic LFs and stability over a few weeks in culture.
“Ectopic Lymphoid Follicle Formation and Human Seasonal Influenza Vaccination Responses Recapitulated in an Organ-on-a-Chip” from Goyal et.al. (2022)
https://onlinelibrary.wiley.com/doi/10.1002/advs.202103241