Oligoclonal Peyer's patch follicles in the terminal small intestine of cattle

In small ruminants, the development of B cells differs from that in mice or in man. The anti-body repertoire is expanded in the Peyer's patches of the terminal ileum where each B-cell follicle is found by a few cells. To investigate the amount of founder clones in bovine ileal follicles, we have used sex mismatched cattle twins. These animals are chimeric due to placental anastomoses. Y-chromosome targeted in situ hybridization was used to trace donor-derived cells of the male genotype in a female recipient (called a freemartin). A strong clustering of lymphoid cells originating from either twin was seen in the ileal Peyer's patches (IPPs). Furthermore, the follicles displayed a low amount of immunoglobulin heavy chain gene configurations in comparison with the splenic or jejunal follicles. These findings strongly suggest that as in sheep, the B-cell follicles in cattle IPPs develop oligoclonally.