Leukemia Inhibitory Factor Expression and Regulation within the Testis

Leukemia inhibitory factor (LIF) is a pleiotropic cytokine known to control the proliferation and survival of stem cells including primordial germ cells and gonocytes. This led us to study the origin and regulation of testicular LIF. The LIF transcript was detected in the rat testis by RT-PCR from 13.5 days postcoitum until adulthood. LIF expression was investigated further in vitro in seven different highly purified testicular cell populations using RT-PCR and bioassays combined with neutralization experiments. LIF was found to be produced by peritubular cells and, to a much lesser extent, by the other testicular somatic cell types. No LIF was detected in meiotic and postmeiotic germ cell-conditioned medium, and only low levels of LIF were detected in spermatogonia-conditioned medium. Large amounts of bioactive LIF were measured in testicular lymph. While LIF production was greatly enhanced in presence of serum, lipopolysaccharide, and TNFα further increased this production in peritubular and Sertoli cel...