IgA antibodies in the bile of rats. III. The role of intrathoracic lymph nodes and the migration pattern of their blast cells.

Eight weeks after rats had had their mesenteric lymph nodes (MLN) removed surgically, they were found to be still able to generate substantial titres of biliary IgA-antibodies after antigens were injected into their Peyer's patches. This suggested that systemically significant IgA production could be induced in extra-abdominal lymphoid tissue. It was found that the intrathoracic lymph nodes (ITLN) were an important source of IgA production. These nodes could be stimulated to produce biliary antibody by introducing antigen either into the peritoneal cavity or directly into the thorax. Cells forming IgA were identified in the ITLNs by haemolytic plaque assays and immunoperoxidase techniques. In spite of this, immunoblasts obtained from the ITLNs, and labelled with 125IUdR did not localize in the gut after i.v. injection to anywhere near the extent that immunoblasts from the MLN did. Instead they seemed to have a predilection for localizing in the lungs.