Natural killer (NK) cells are leukocytes within the innate immune system, acting as a first line of defense against cancer and virally infected cells. NK cell responses—whether “killing” or “tolerant”—are regulated by interactions between activating and inhibitory receptors and their ligands. Currently, there remains a need for comprehensive in vivo models featuring humanized NK cell receptors, including key proteins encoded by the KIR and NKC gene clusters.

Killer cell immunoglobulin-like receptors (KIR) form a highly polymorphic gene cluster expressed by NK and certain T cell subtypes, while the Natural Killer Gene Complex (NKC) encodes several C-type lectin-like receptors, such as the NKG2 family, found across various immune cells. To introduce a novel NK gene cluster-related in vivo model, Biocytogen has used advanced gene-editing technology to humanize ~150,000 base pairs of KIR gene cluster DNA (B-hKIR mice) and 0.9 million base pairs of NKC gene cluster DNA (B-hNKC mice) on a C57BL/6 background. In this combined B-hNKC/hKIR mouse model, 29 functional genes have been modified.

The immunophenotype of B-hNKC/hKIR mice is consistent with that of wild-type C57BL/6 mice. Human proteins NKG2A, NKG2C, CD94, NKG2D, and CD161 are detectable on NK cells, while human CLEC9A is observed on CD8a+ and CD103+ dendritic cells in the spleen. Human CLEC12A is expressed on T cells, macrophages, monocytes, and dendritic cells, and human LOX1 is present on activated macrophages, monocytes, and neutrophils in the bone marrow. Additionally, human CD69 is expressed on activated T cells, B cells, NK cells, macrophages, monocytes, neutrophils, and dendritic cells in the spleen. In B-hKIR mice, human KIR2DL1, KIR2DL3, and KIR3DL2 are detectable on NK cells, and mRNA for human KLRF2, CLEC2A, TMEM52B, CLEC1A, and CLEC2D is also expressed in B-hNKC/hKIR mice.

This B-hNKC/hKIR mouse model provides an advanced platform for NK-targeted research and serves as a valuable in vivo system for preclinical studies.