Markers for the lymphatic endothelium: In search of the holy grail?

The ability to discriminate reliably at the histological level between bloo d and lymphatic microcapillaries would greatly assist the study of a number of biological and pathological questions and may also be of clinical utili ty. A structure-function comparison of these types of microcapillary sugges ts that differences which could function as markers to allow discrimination between blood and lymphatic endothelium. should exist. Indeed, to date a v ariety of such markers have been proposed, including basement membrane comp onents, constituents of junctional complexes such as desmoplakin and enzyme s such as 5'-nucleotidase. Additionally, a variety of cell surface molecule s are thought to be differentially expressed, including PAL-E, VEGFR-3, pod oplanin, and LYVE-1. Several of the lymphatic markers proposed in the liter ature require further characterization to demonstrate fully their lymphatic specificity and some have proven not to be reliable. The relative merits a nd drawbacks of each of the proposed markers is discussed. (C) 2001 Wiley-L iss, Inc.