Interaction of activated natural killer cells with normal and tumor vessels in cranial windows in mice

A mammary carcinoma, MCa IV, was grown in syngeneic C3H mice in a cranial window preparation which permitted the in vivo observation of the growth and microcirculation of the tumors. Fluorescently labeled activated natural killer (A-NK) cells were injected into the external carotid artery and their interactions with normal and tumor vessels were quantified by video microscopy. Cells which entered the tumor vessels adhered heterogeneously to these vessels, regardless of vessel size or blood flow rates and bound with an efficiency ranging from 0 to 82% of the incoming cell flux. Normal brain tissue showed significantly fewer binding cells per microscopic field (9 +/- 5 vs 85 +/- 27 cells/1.3 mm2) and the few cells which were retained by the normal tissue were highly deformed, suggesting mechanical rather than adhesive entrapment. These studies indicate that A-NK cells bind in high numbers to segments of the vessels of mammary tumors growing in an intracranial site when administered through an arterial route; however, some tumor vessels may escape recognition by these cells. These findings suggest that A-NK cells may be used as carriers of genes for anti-cancer agents.