Abstract: Granulocytes, particularly neutrophilic granulocytes, also called polymorphonuclear leukocytes (PMN), have been found to retain their immunological properties after enucleation. Moreover, in contrast with normal granulocytes, enucleated granulocytes are stable when stored in frozen condition. The invention relates to the enucleated granulocytes, especially in frozen condition, to a process for preparing the enucleated granulocytes, to a process for assaying antibodies against granulocytes, and to a kit for carrying out the latter process.

Abstract: The invention relates to a method for increasing the hybridization of cells in vitro and for increasing the production and secretion of substances, formed by such cell hybrids by adding endothelial cells and/or the supernatant of endothelial cells to a hybrid culture. In particular the invention is concerned with a method for increasing the production of monoclonal antibodies in vitro by means of a hybridoma technique by adding endothelial cells and/or the supernatant of endothelial cells to a hybridoma culture. Usually human endothelial cells and/or the supernatant of human endothelial cells are used. Finally the invention relates to endothelial cells and/or the supernatant of endothelial cells for use for increasing the hybridization of cells in vitro and for increasing the production and secretion of substances, formed by such cell hybrids, and for increasing the production of monoclonal antibodies in vitro.