INFLUENCE OF A LYMPH-NODE ENVIRONMENT ON INVASIVENESS OF METASTATIC TUMOR-CELLS

BACKGROUND: We investigated the possibility that lymph nodes might inc rease metastatic efficiency of tumor cells lodged there by measuring c hanges,in tumor cell invasiveness after physical contact with an in vi tro approximation of a lymph node environment. STUDY DESIGN: The exper imental model involved growing Lewis lung carcinoma (LL) or B16 melano ma cells on microcarrier beads, rolling them on a ''lymph node endothe lial surface,'' which was created by growing endothelial cells on a di fferentiating acid extract of lymph node biomatrix, and testing the ab ility of those tumor cells to invade across matrigel-coated filters at rest (buffer) and in response to a chemotactic stimulus (3T3 conditio ned media). RESULTS: Compared with contact with plastic, LL invasivene ss was increased fivefold (buffer or conditioned media) and B16 invasi veness fourfold (conditioned media). Tumor cell invasiveness was not i ncreased by exposure to the acid extract of biomatrix alone. Invasiven ess to buffer or conditioned media after exposure to endothelial cells alone was 70 and 54 percent (LL) and 42 and 80 percent (B16), respect ively, of the invasiveness induced by exposure to both. Compared with invasiveness induced by exposure to lymph node (100 percent), exposure to a ''lung endothelial surface'' induced invasiveness of 63 and 85 p ercent (LL) and 40 and 52 percent (B16) to buffer and conditioned medi a, respectively. Exposure to a hepatic endothelial surface induced inv asiveness similar to that induced by lymph node; 90 and 82 percent (LL ) and 110 and 86 percent (B16) of lymph node-induced invasiveness. CON CLUSIONS: A lymph node environment may modulate the metastatic potenti al of tumor cells.