Effects of a metastatic (13762) and nonmetastatic (R3230AC) mammary adenocarcinoma on radiocolloid localization in regional lymph nodes in Fischer 344 rats

Effects of a metastatic and nonmetastatic tumor on radiocolloid localization in regional lymph nodes in the rat were studied in order to examine further the hypothesis that suppression of radiocolloid uptake results from inhibition of macrophage phagocytic function by tumor products. On the basis of data obtained in the present model using homogenates of autologous spleen and two weakly immunogenic tumors introduced into the foot pad of rats, it is proposed that decreased radiocolloid uptake induced by a regional neoplasm may result from proliferation of nonphagocytic cellular elements within the regional lymph nodes and alterations in the cell population at the site of radiocolloid injection, which impede the transport of interstitially administered radiocolloid and its access to phagocytic macrophages, within primary and secondary regional lymph nodes. In its inception, therefore, suppression of radiocolloid uptake is not unique to neoplasia and may not directly reflect altered phagocytosis.