B7-H4 (human, recombinant)

B7-H4 is a glycoprotein linked to the cell membrane via glycosylphosphatidylinositol (GPI) and a member of the B7-CD28 immune checkpoint protein family.¹ It is composed of an extracellular domain containing immunoglobulin (Ig) variable (IgV) and Ig constant (IgC) domains with several cysteine residues and N-glycosylation sites.^2,1 B7-H4 is found on T cells, B cells, natural killer (NK) cells, dendritic cells, monocytes, and tumor cells, and B7-H4 mRNA is expressed in non-lymphoid tissues such as the lungs, testis, and pancreas.^1,3,4 The expression of B7-H4 is induced by inflammatory mediators and cytokines, and it acts as a co-stimulatory molecule to promote regulatory T cell development and inhibit T cell activation, cell cycle progression, proliferation, and cytokine production.^1,3 VTCN1 is overexpressed in a variety of cancers, including breast and ovarian cancers, and the levels of expression correlate with lymph node metastasis, cancer progression, and mortality.^4,5 siRNA knockdown of VTCN1, the gene encoding B7-H4, decreases proliferation and migration of pancreatic cancer cells in vitro.⁵ Knockout of VTCN1 in mice reduces lung metastasis and increases survival in a metastatic breast cancer mouse xenograft model. Cayman’s B7-H4 (human, recombinant) protein can be used for cell-based assay applications. This protein is a disulfide-linked homodimer. The reduced monomer, comprised of B7-H4 (amino acids 29-258) fused to human IgG1 Fc at its C-terminus, consists of 471 amino acids and has a calculated molecular weight of 52.3 kDa. As a result of glycosylation, the monomer migrates at approximately 66 to 76 kDa by SDS-PAGE under reducing conditions.

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1. Collins, M., Ling, V., and Carreno, B.M. The B7 family of immune-regulatory ligands. Genome Biol. 6(6), 223 (2005).

2. Janakiram, M., Shah, U.A., Liu, W., et al. The third group of the B7-CD28 immune checkpoint family: HHLA2, TMIGD2, B7x, and B7-H3. Immunol. Rev. 276(1), 26-39 (2017).

3. Zang, X., Loke, P., Kim, J., et al. B7x: A widely expressed B7 family member that inhibits T cell activation. Proc. Natl. Acad. Sci. USA 100(18), 10388-10392 (2003).

4. Fauci, J.M., Straughn, J.M., Jr., Ferrone, S., et al. A review of B7-H3 and B7-H4 immune molecules and their role in ovarian cancer. Gynecol. Oncol. 127(2), 420-425 (2012).

5. Wang, L., Heng, X., Lu, Y., et al. Could B7-H4 serve as a target to activate anti-cancer immunity? Int. Immunopharmacol. 38, 97-103 (2016).