Trafficking of activated lymphocytes into the RENCA tumour microcirculation in vivo in mice.

The aim of the study was to establish a model of tumour microcirculation in vivo using the murine renal cell carcinoma cell line (RENCA) implanted into the mouse cremaster muscle, and subsequently to investigate the trafficking of syngeneic lymphocyte subpopulations into both the RENCA tumour and the surrounding normal cremaster muscle microcirculation. We have demonstrated that RENCA tumour cells, at a dose of 1.5 x 10(5) per 30 microl injected into the cremaster muscle, reproducibly produced a vascularized tumour suitable for in vivo microscopy at 10-14 days. Injection of fluorescently labelled effector cells (1 x 10(6)) including naive splenocytes, T-cell enriched populations and ex vivo interleukin 2 (IL-2)-activated splenocytes all migrated to and flowed through both the tumour and the normal microcirculation, with negligible adhesion. However, we observed the selective recruitment, localization and arrest of IL-2-activated splenocytes (P < 0.05) into the tumour microcirculation, and the subsequent extravasation of cells into the tumour intestitium in some instances. This did not occur with the other effector cells. We also observed the absence of leucocyte rolling in the tumour microcirculation, suggesting an impairment in adhesion molecule expression on the tumour endothelium. We have therefore established the potential of this model for defining further effector cell-tumour-endothelium interactions.