The production of Csf1 by macrophages as a modulator of spermatogonial fate (DeFalco et al 2014) and IL-6 by seminoma cells (testicular germ cell tumors; Klein et al. 2016) are two examples of the potential cross-talk mediators between testicular immune and germ cells in different physiological states. The gene discussed is CSF1; the disease is testicular germ cell tumor.