Basic Information

Strain name
C57BL/6Cd40tm1(CD40)Cd40lgtm1(CD40LG)/Bcgen
Common name
B-hCD40/hCD40L mice
Background
C57BL/6
Catalog Number
121335

Description

CD40 (CD40 molecule) is a member of the tumor necrosis factor receptor superfamily expressed on antigen-presenting cells (APC), such as dendritic cells (DC), B cells, and monocytes as well as many non-immune cells and a wide range of tumors [1]. Engagement with its trimeric ligand CD154 on activated T helper cells results in APC activation, which has been found to be essential in mediating a broad variety of immune and inflammatory responses including T cell-dependent immunoglobulin class switching, memory B cell development, and germinal center formation. Agonistic CD40 monoclonal antibodies (mAbs) have been shown to activate APC and promote anti-tumor T cell responses. Thus, agonistic anti-CD40 mAb may serve as a new class of antitumor  therapeutics that potentiate immunity via a different mechanism than the blocking immune checkpoint inhibitors such as anti-CTLA4 or anti-PD-1.

CD154, also called CD40 ligand or CD40L, is a protein that is primarily expressed on activated T cells and is a member of the TNF superfamily of molecules. It binds to CD40 (protein) on antigen-presenting cells (APC), which leads to many effects depending on the target cell type. In total CD40L has three binding partners: CD40, α5β1 integrin and αIIbβ3. CD154 acts as a costimulatory molecule and is particularly important on a subset of T cells called T follicular helper cells (TFH cells). On TFH cells, CD154 promotes B cell maturation and function by engaging CD40 on the B cell surface and therefore facilitating cell-cell communication. A defect in this gene results in an inability to undergo immunoglobulin class switching and is associated with hyper IgM syndrome. Absence of CD154 also stops the formation of germinal centers and therefore prohibiting antibody affinity maturation, an important process in the adaptive immune system.

Reference: Dostert C, Grusdat M, Letellier E, Brenner D. The TNF Family of Ligands and Receptors: Communication Modules in the Immune System and Beyond. Physiol Rev. 2019;99(1):115-160. doi:10.1152/physrev.00045.2017

Targeting Strategy

Exons 2-7 of the mouse Cd40 gene, which encodes the extracellular region, were replaced by human CD40 exons 2-7 in B-hCD40/hCD40L mice. Exons 2-5 of the mouse Cd40l gene, which encodes the extracellular region, was replaced by human CD40L exons 2-5 in B-hCD40/hCD40L mice.

mRNA Expression

Species-specific analysis of CD40/CD40L gene expression in wild-type C57BL/6 mice and B-hCD40/CD40L mice by RT-PCR. Mouse CD40/CD40L mRNA was detectable in splenocytes of wild-type C57BL/6 mice (+/+). Human CD40/CD40L mRNA was detectable only in homozygous B-hCD40/CD40L (H/H) mice.

Surface Expression in Splenocytes

Species-specific CD40 expression in homozygous B-hCD40/hCD40L mice by flow cytometry. Splenocytes were collected from wild-type C57BL/6 mice (+/+) and homozygous B-hCD40/hCD40L mice (H/H) stimulated with anti-CD3ε in vivo (7.5 μg/mice, stimulation for 24 hours, i.p.), and analyzed by flow cytometry with species-specific anti-CD40 antibody. Mouse CD40 was detectable in wild-type mice. Human CD40 was exclusively detectable in homozygous B-hCD40/hCD40L mice.

Surface Expression in Thymocytes

Species-specific CD40L expression in homozygous B-hCD40/hCD40L mice by flow cytometry. Thymocytes were collected from wild-type C57BL/6 mice (+/+) and homozygous B-hCD40/hCD40L mice (H/H) and stimulated with PMA & Ionomycin, then analyzed by flow cytometry with species-specific anti-CD40L antibody. Mouse CD40L was detectable in wild-type mice. Human CD40L was exclusively detectable in homozygous B-hCD40/hCD40L mice.