Gut and bronchus associated lymphoid tissue: an overview.

The mucosal lymphoid aggregates in lung and gut contain precursor cells destined to seed mucosal tissues with IgA containing cells. It is likely that both tissues also are sources of both IgE B cell precursors as well as the cells responsible for their regulation (38). Although the traffic of B cells is relatively well understood from the standpoint of IgA, the factors responsible for localization in mucosal tissue are at best unclear. Furthermore, little is known about the migration patterns of helper or suppressor cells of any kind and these may have, if derived from mucosal tissue, a preferential site of action in the mucosa. The mucosal mast cell may well be a cell of different lineage than the mast cell from the peritoneal cavity and may itself have a mucosal localization pattern. Much more work needs to be done to render some of these speculations onto a better factual base, and to harness these systems in provision of better approaches to vaccination and control of disease.