Studies on the lymphocytes of sheep. I. Recirculation of lymphocytes through peripheral lymph nodes and tissues.

Recirculating lymphocytes were collected from the efferent ducts of peripheral somatic nodes and incubated in vitro with 51Cr. After washing, the labeled cells were returned to the sheep by i.v. injection. The partitioning of the labeled cells between blood and efferent (intermediate) lymph, or between efferent and afferent (peripheral) lymph was monitored for the next 24 h by assaying the radioactivity in appropriate samples of cells. The labeled lymphocytes took several hours to migrate through the nodes so that they equilibrated between blood and lymph in about 10 h. This pattern was not altered grossly during the inductive phase of an immune response. The small numbers of lymphocytes which migrated through peripheral tissues entered the lymph at least quickly as those that migrated through lymph nodes.