a, Mice were injected with anti-α4β7 or isotype control antibody 2h before photoconversion of 3 PPs using laser light. Organs were harvested 20h later and cells analyzed by FC. b, Gating strategy for follicular B cells (CD19+B220+IgD+) and germinal center B cells (CD19+B220+GL7+) from a representative mouse. c-f, Absolute cell number and cell frequency of KRED and KGREEN cells out of Follicular B cells (c, d) and GC B cells (e, f). Cells were isolated from non-photoconverted (c, e) and photoconverted (d, f) PPs. g-h, Absolute cell number and cell frequency of KRED and KGREEN T cells from non-photoconverted (g) and photoconverted (h) PPs. i, Model scheme: anti-α4β7 prevents entry of new (red and green) cells into PPs, but does not affect cell egress. This process renders PPs smaller. Data shown as individual values, mean and SD. Unpaired analysis was done using Mann-Whitney test, p value is indicated