Isolation of dendritic cells from rat intestinal lymph and spleen

Dendritic cells (DC) are rare cells in peripheral tissues, and their isolation from tissues is fraught with problems. Thus, the proportion of DC within a tissue that is extracted is unknown, isolation procedures may select for subpopulations, and the isolation procedure itself may affect their properties. As part of their life history, DC migrate from peripheral tissues, via peripheral, afferent lymph to lymph nodes, even in the absence of exogenous antigenic stimulation. They are extracted within the node and very few, if any, appear in efferent lymph. These lymph DC (L-DC) represent a population that has matured in the periphery, that may have acquired antigen (Ag), and that may be engaged in active Ag transport to lymph nodes. As such they are a physiologically relevant DC population. In large animals such as sheep and cattle, L-DC can be isolated by direct cannulation of peripheral lymphatics, but yields are relatively low. In rodents, direct cannulation of some peripheral lymphatics is possible (1), but yields of cells are minuscule. To get around this problem we and others (1 -7), have utilized lymphadenectomy as a means of collecting pseudo-afferent lymph. When lymph nodes are removed, over a period of weeks, the afferent and efferent lymphatics join as part of the healing process, leaving cells in peripheral lymph free to enter central lymph. Central lymphat ics are relatively easy to cannulate, and cannulation can be maintained for considerable periods of time (see Note 1).