Tumour adjacent macrophage function in experimental tumours

This study describes in vivo methodology for evaluating whole body and Tumour Adjacent Macrophage (TAM) phagocytic function in tumour-bearing rats. 29 Wistar rats were inoculated with 1 x 5 mm cylinders of syngeneic NGW-adenocarcinoma im in the right hind leg. 10 rats were given iv zymosan (3mg/100 g b.w.) for systemic activation of macrophages, 9 rats were given intratumour injection of zymosan (3mg/100g b.w.) for local activation and 10 rats were untreated controls. 10 days after tumour inoculation whole body phagocytic rate was estimated with dynamic liver RES scintigraphy. Tumour and blood radionuclide activity was measured. Dynamic liver RES scintigraphy measures whole body macrophage phagocytic rate (k) of iv 99Tcm Nanocoll albumin test colloid. TAM phagocytic rate is calculated from the final uptake in tumor/injected dose x k. Systemic macrophage activation caused a significant increase in liver and spleen weight and whole body phagocytic rate (0.65 +/- 0.02 versus 0.56 +/- 0.03% s-1). The TAM phagocytic rate was significantly elevated in tumors treated by local macrophage activation (0.003 +/- 0.00 versus 0.001 +/- 0.00% s-1). This study suggests that the TAM phagocytic rate is a sensitive indication of local macrophage activity.