Human–mouse cell hybrid with human multiple Y chromosomes

Abstract

HUMAN–mouse cell hybrids usually exhibit preferential loss of human chromosomes^1,2. After a time interval, which depends in part on the cell types used, most or sometimes all the human chromosomes segregate out from the hybrid cells³. In the course of investigation of the phenomenon of preferential loss of human chromosomes from hybrids between the mouse cell line RAG and human leukocytes, we isolated and analysed sixteen human–mouse (RH) hybrids. Seven of these hybrids had retained the human Y chromosome. Five of these had only one copy per cell of Y, one had two copies per cell and one, RH-28, had four copies of the Y in many cells. We decided to study more extensively this hybrid which seemed to have lost all the human chromosomes except number 17 and the Y.