CTLA-4 (cytotoxic T-lymphocyte-associated protein 4), also known as CD152, plays an important regulatory role in T cell activation. Cytotoxic T lymphocyte related proteins are expressed on the surfaceof T cells, and competitively binds to B7-1 (CD80) and B7-2 (CD86) on the surface of antigen-presenting cells (APCs) to block the interaction between B7 and CD28 on the surface of T cells, thus inhibiting T cell activation. CTLA-4 is the first immunological target attracting clinical concern, and plays an important role in the negative regulation of immune response. The inhibition of CTLA-4 by its inhibitory antibodies enhances T cell activity. The CTLA-4 antibody is also the first FDA-approved antibody to treat advanced melanoma.
mRNA expression verification:
Fig 1. Molecular identification of the B-hCTLA-4 humanized mice. Mouse CTLA-4 mRNA was detected in both the wild type and the B-hCTLA-4 heterozygous mice, while human CTLA-4 mRNA was detected only in the B-hCTLA-4 heterozygous mice.
Protein expression verification:
Fig 2. Spleen cells from both wild type (WT) C57BL/6 and the B-hCTLA-4 homozygous mice were analyzed by flow cytometry. Mouse CTLA-4+ T cells were detected in the WT mice, while human CTLA-4+ T cells were detected in the B-hCTLA-4 homozygous mice.
CTLA-4 antibody efficacy validation:
Fig 3. Murine colon tumor MC38 cells were subcutaneously injected into the B-hCTLA-4 homozygous mice, which were grouped when the tumor size reached 100 mm3 (n=5). The human CTLA-4 antibody Yervoy significantly inhibited tumor growth at 3 different doses, suggesting that the B-hCTLA-4 mice are powerful tools for human CTLA-4 antibody in vivo pharmacological efficacy validation.