EFFECTS OF CLODRONATE-CONTAINING LIPOSOMES ON TESTICULAR MACROPHAGES AND LEYDIG-CELLS IN-VITRO

We undertook the present studies to determine if clodronate-containing liposomes have direct effects on Leydig cells. Macrophages and Leydig cells were isolated and maintained separately in culture. Following t reatment with clodronate-containing liposomes, macrophages were killed in a dose-response fashion over a range of 5-200 mu l liposomes. By c omparison, a 500 mu l dose was required to kill Leydig cells, but this was not dependent upon clodronate since liposomes containing buffer e licited an identical response. The concentration of testosterone in me dium h-om Leydig cells treated with clodronate-containing liposomes wa s significantly reduced compared with untreated cells. However, we sub sequently found that liposomes can adsorb testosterone. Therefore, tes tosterone production was determined at various times following removal of liposomes from Leydig cells, thereby circumventing this complicati on. It was found that testosterone production was not altered by lipos omes under these conditions. Finally, free clodronate had no effect on testosterone production, even at doses representing the amount presen t within the 500 mu l dose of liposomes. In summary, clodronate-contai ning liposomes killed testicular macrophages al a far smaller dose tha n required to kill Leydig cells. Most importantly, neither Liposomes n or free clodronate had a direct effect on testosterone production. Thu s, clodronate-containing liposomes represent a valuable tool to study Leydig cell-macrophage interactions.