Quantitative detection of the HVEM-BTLA checkpoint receptor cis-complex in human lymphocytes.

The herpesvirus entry mediator (HVEM) (TNFRSF14) engagement of the checkpoint inhibitory receptor B and T lymphocyte attenuator (BTLA) limits immune responses of T and B lymphocytes. HVEM and BTLA form signaling complexes in trans and when coexpressed, complexes in cis, creating a unique immune checkpoint. The function of the HVEM-BTLA cis-complex is not well understood primarily due to a lack of reagents that specifically measure the HVEM-BTLA cis-complex.

Epitope topography of agonist antibodies to the checkpoint inhibitory receptor BTLA.

B and T lymphocyte attenuator (BTLA) is an attractive target for a new class of therapeutics that attempt to rebalance the immune system by agonizing checkpoint inhibitory receptors (CIRs). Herpesvirus entry mediator (HVEM) binds BTLA in both trans- and cis-orientations. We report here the development and structural characterization of three humanized BTLA agonist antibodies, 22B3, 25F7, and 23C8.