Functional anatomy of lymph nodes. II. Peripheral lymph-borne mononuclear cells.

In the rabbit a number of large mononuclear cells with ruffled surface membranes travel from the skin and superficial tissues of the leg, via the lymphatics, to the popliteal lymph node: they constitute 40-50% of the total cell population in the afferent lymph. About 10% of these cells are actively phagocytic when tested in vitro and about 3% are found to contain Langerhans granules. After isotopic labelling the majority of lymph-borne mononuclear cells can be detected within the regional node for at least 24 hours; most being located in the paracortex and a few in the interfollicular cortex. It is proposed that these cells, including those containing Langerhans granules, belong to the "mononuclear phagocyte system." Possible functions of these lymph-borne cells are discussed with particular reference to antigen transport.