Capillaries provide a vast interface between the blood and the tissues that is crucial for regulating nutrient delivery, blood coagulation and transmigration of leukocytes to sites of infection. The growth of new capillaries from pre-existing vessels (angiogenesis) is essential for normal embryogenesis and growth, but also occurs in the development of many diseases. Although relatively little is known about endothelial cell biology, progress is nevertheless being made towards understanding angiogenesis, and several laboratories have begun to identify cell adhesion molecules that may be required for the growth of microvessels.

The levels of P-selectin mRNA and polypeptide were analyzed in bovine capillary cells treated with or without the cytokine tumor necrosis factor-alpha. The 3 kb P-selectin mRNA was upregulated three- to five-fold in cytokine-stimulated cells. The increase in mRNA correlated with a dramatic but short-lived increase in P-selectin polypeptide as determined by metabolic-labeling and immunoadsorption. These data confirm earlier studies on mouse P-selectin expressed in a mouse endothelioma cell line and further indicate that P-selectin function can be regulated not only by rapid translocation to the cell surface but also by cytokine-stimulation of P-selectin biosynthesis.