gut imprinting molecules, such as α4β7 integrin and CCR9 [9,10].
B cells, a major component of PP cells (~75%), are preferentially
located in the follicle region (Figs. 1 and 3). Unlike other lymphoid
organs, formation of germinal centers (GC) occurs in the PPs even
under homeostatic conditions by the continuous stimulation from
commensal bacteria, in which leads to the creation of molecular and
Fig. 1. Microarchitecture of murine Peyer's patches. Purified T cells (green) and B cells
(red) were chemically labeled with carboxyfluorescein succinimidyl ester and arboxy
SNARF-1, respectively, and adoptively transferred into mice. Fifteen hours after the
transfer, cell distribution in the Peyer's patches was observed at the whole tissue level
by using macro-confocal microscopy.cellular environment for class switching of B cells from IgM to IgA
(Fig. 3). Thus, PPs contain B cells at several differentiation and
maturation stages: IgM+B220+ (~70%), IgM+IgA+B220+ (~1%),
IgA+B220+ (~3%), and IgA+B220− (~0.5%).