N. Alitheen et al., Segregation of B lymphocytes into stationary apoptotic and migratory proliferating subpopulations in agglomerate cultures with ileal epithelium, EUR J IMMUN, 31(9), 2001, pp. 2558-2565
The B lymphocyte-epithelial cell interactions that define the microenvironm
ent of the ileal Peyer's patch, the primary B lymphocyte organ of the fetal
lamb, have been replicated in tissue culture. Mixed suspensions of Real ep
ithelial cells, lymphocytes and fibroblasts from fetuses of 63-103 days of
gestation organized into macroscopically visible agglomerates within 72 h.
These agglomerates contained translucent spherical cavities and were enclos
ed within a marginal cell layer and surrounded by an expanding corona of em
igrating cells. The lining of the cavities and the marginal layer consisted
of well-differentiated, polarized columnar ilea[ epithelial cells. One pop
ulation of B lymphocytes in the initial mixed suspension differentiated int
o two discrete populations reproducing the characteristics of intact fetal
ileal Peyer's patches. B cells apposed to follicle-associated epithelium (F
AE) within agglomerates underwent apoptosis. The other population of emigra
nt B cells proliferated and expressed the BAQ44A differentiation marker. Di
fferentiation of ilea[ epithelial cells into FAE, typical of Peyer's patche
s, was markedly accelerated. The mutually inductive influences of intestina
l epithelial cells and B lymphocytes in these agglomerates replicate normal
mid-gestational fetal development of the mucosal immune system and afford
new opportunities for its further investigation.