Leydig cells do not have Fc receptors

It has been reported that Leydig cells have Fc receptors, which traditionally have been considered markers specific for macrophages and polymorphonuclear leukocytes. The purpose of this investigation was to study further this phenomenon and also to determine if Leydig cells and macrophages could be separated from each other either by density gradient centrifugation using Percoll or by differential detachment with trypsin treatment of cultures of crude interstitial preparations. Interstitial cells were obtained by collagenase digestion of rat testis and established in culture. These cultures were reacted for 3 beta-steroid dehydrogenase and Fc receptor and viewed with phase contrast microscopy. No individual cells were positive for both steroid dehydrogenase activity and Fc receptors. The order in which the cells were stained for these two markers did not influence the results. Trypsin treatment of these crude interstitial cultures removed over 90% of the Leydig cells and approximately 20% of the macrophages. Macrophages were located in the same portion of Percoll gradients as the less dense (Population I) Leydig cells, while Leydig cells found in the dense area of the gradient (Population II) were not contaminated with macrophages. These studies indicate that Leydig cells do not have Fc receptors and that a subpopulation of Leydig cells can be isolated free of macrophages using density gradient centrifugation.