Compartmentalization of specific B-cells in sheep mucosae associated lymphoid organs

Numerous studies have shown that Peyer's patches (PP) contribute to the seeding of other lymphoid organs in sheep. This was demonstrated by perfusing labeled lymphocytes in PP, and later investigating their presence in drainage lymph nodes, spleen, peripheral blood or bone marrow. These data showed that PP export considerable numbers of cells every day, but provided no information as to their specificity. In this work, we used the enzyme-linked immunosorbent assay (ELISA) spot method to investigate, in the peripheral blood, mesenteric and cervical lymph nodes and tonsils from ten sheep, the numbers of specific B-cells, directed to four common bacteria of the oro-pharyngeal area of mammals: Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae or Klebsiella pneumoniae. The data were obtained from five sets of monozygous sheep, one animal of each pair being previously fed ribosomal preparations of these bacteria. Both prior to and after oral challenge, specific B-cells could be found in all the tissues tested. They were mostly IgG-producing cells and preferentially located in oro-pharyngeal drainage lymph nodes and tonsils. Their numbers increased in these lymph nodes after stimulation, while they decreased in mesenteric lymph nodes. These observations are consistent with the current hypothesis suggesting intestinal sensitization, proliferation and fast emigration of specific B-cells after oral challenge.