Figure 1. Generation strategy of humanized ICOS mice in the C57BL/6J mouse genetic background. The coding sequences for the extracellular domain of human ICOS, and the transmembrane and intracellular domains of murine Icos were inserted into the ATG position of the mouse Icos locus, in order to replace the endogenous gene expression with the expression of the humanized chimeric protein.
Figure 2. Expression of ICOS in the activated spleen lymphocytes of humanized ICOS mice is detected by FACS. The spleen lymphocytes of heterozygous humanized ICOS mice were stimulated by anti-CD3 and anti-CD28 for 48 h along with a group undergoing no stimulation, and then harvested for staining. The expression of humanized ICOS was detected by FACS after antibody staining. The results showed that the active expression of humanized ICOS can be detected in both activated CD4+ and CD8+ T lymphocytes collected from heterozygous humanized ICOS mice.