Lymphocyte-induced angiogenesis: a morphometric study in the chick embryo chorioallantoic membrane

A morphometric analysis was carried out on the chorioallantoic membrane (CAM) vasculature in chicken embryos treated (1) with phytohemagglutinin (PHA), (2) with supernatants of cell cultures of normal human T lymphocytes and (3) of T lymphocytes stimulated with PHA in order to evaluate their angiogenic properties. In the left chorioallantoic artery, the number of primary collaterals, and the number and length of secondary and tertiary collaterals were measured. In the series treated applying procedures 1 and 3, the mean value of the total number of all the collaterals was higher than that of the normal-developing CAM vessels, while the length of the secondary and tertiary collaterals was lower than that of the normal-developing blood vessels. In the series treated following procedure 2, no statistically significant differences were observed between experimental and control series in any parameters evaluated. The possible significances of these morphological findings are discussed with reference to the angiogenic roles played by human T lymphocytes, probably determined by lymphokines released after the activation of these cells by PHA, and by PHA alone, probably dependent on its aspecific mitotic activity.