Figure 2.

Lymphatic intravasation in the healthy organism. (A) Schematic representation of DC entry into initial lymphatic vessels. Upon maturation, DCs upregulate expression of CCR7, a receptor for the LEC-expressed chemokine CCL21, enabling them to navigate towards a nearby lymphatic vessel and to enter the lumen via flap junctions between adjacent LECs. In inflammatory conditions, additional chemokines and adhesion molecules may be involved in this process. (B) Illustration of the benign metastasis process. Occasionally, benign stromal cells, e.g., dermal nevus cells, can enter lymphatic vessels (LVs) and reach draining lymph nodes, where they form clusters within the subcapsular sinus. Lymphatic entry may be mediated by minor trauma, low-grade invasive potential of the nevus cells, or by lymphatic engulfment of single or clustered nevus cells.