The CTLA-4/CD3-ratio also showed differences between different tumor categories: Lowest values were found in lymphomas (5 ± 7) and germ cell tumors (8 ± 24) while highest values were seen in melanocytic (25 ± 43) as well as epithelial tumors (18 ± 48, p < 0.0001, Table 1). Here, CTLA4 is linked to testicular germ cell tumor.