• C-type lectin member 5A (CLEC5A), also known as myeloid DAP12-associating lectin (MDL-1), is a pattern recognition receptor which plays a role in innate immune system. It is a type II transmembrane protein that is expressed by monocytes, macrophages and neutrophils. It requires association with an adaptor protein, DAP12 or DAP10, activation the Syk-AKT signaling pathways. CLEC5A participate in multiple acute and chronic inflammatory diseases, such as hemorrhagic fever, lethal shock, and the development of autoimmune arthritis. Some recent studies suggest that activating CLEC5A can enhance the phagocytosis of macrophages, demonstrating anti-tumor activity^1,2,3.
• Biocytogen developed a CLEC5A humanized mice by replacing the extracellular region sequences of mouse Clec5a with human CLEC5A counterpart gene sequences. Preserved the intracellular signaling of mice. Then, confirmed that human CLEC5A protein was expressed in monocytes, macrophages, and neutrophils of homozygous B-hCLEC5A mice(C). 
• The mice can be used for preclinical studies of target-related disease especially in pharmacodynamics and safety evaluations.

1. Chen ST, et al. Nat Commun. 2017
2. Chen ST, et al. PLoS Pathog. 2012
3. Kedage V, et al. MAbs. 2022

Gene targeting strategy for B-hCLEC5A mice(C). The extracellular region sequences of mouse Clec5a gene was replaced by human CLEC5A counterpart gene sequences in B-hCLEC5A mice(C). Preserved the intracellular signaling of mice.

Strain specific CLEC5A protein expression analysis in BALB/c mice and homozygous B-hCLEC5A mice(C) by flow cytometry. Bone marrow were collected from wild type BALB/c mice (+/+) and homozygous B-hCLEC5A mice (H/H), and analyzed by flow cytometry with species-specific anti-CLEC5A antibodies. Mouse CLEC5A was detectable in monocytes, macrophages, and neutrophils of BALB/c mice, while human CLEC5A was exclusively detectable in monocytes, macrophages, and neutrophils of B-hCLEC5A mice(C).

Frequency of leukocyte subpopulations in spleen by flow cytometry. Splenocytes were isolated from female wild-type BALB/c mice and homozygous B-hCLEC5A mice(C) (n=3, 7-week-old). A. Flow cytometry analysis of the splenocytes was performed to assess the frequency of leukocyte subpopulations. B. Frequency of T cell subpopulations. Percentages of T cells, B cells, NK cells, dendritic cells, monocytes, macrophages, neutrophils, CD4+ T cells, CD8+ T cells and Tregs in B-hCLEC5A mice(C) were similar to those in BALB/c mice, demonstrating that humanization of CLEC5A does not change the frequency or distribution of these cell types in spleen. Values are expressed as mean ± SEM. Significance was determined by two-way ANOVA test.  *P < 0.05, **P < 0.01, ***p < 0.0001.

Frequency of leukocyte subpopulations in blood by flow cytometry. Blood cells were isolated from female wild-type BALB/c mice and homozygous B-hCLEC5A mice(C) (n=3, 7-week-old). A. Flow cytometry analysis of the blood was performed to assess the frequency of leukocyte subpopulations. B. Frequency of T cell subpopulations. Percentages of T cells, B cells, NK cells, dendritic cells, monocytes, macrophages, neutrophils, CD4+ T cells, CD8+ T cells and Tregs in B-hCLEC5A mice(C) were similar to those in BALB/c mice, demonstrating that humanization of CLEC5A does not change the frequency or distribution of these cell types in blood. Values are expressed as mean ± SEM. Significance was determined by two-way ANOVA test.  *P < 0.05, **P < 0.01, ***p < 0.0001.

Frequency of leukocyte subpopulations in lymph node by flow cytometry. Lymph nodes were isolated from female wild-type BALB/c mice and homozygous B-hCLEC5A mice(C) (n=3, 7-week-old). A. Flow cytometry analysis of the Lymph node was performed to assess the frequency of leukocyte subpopulations. B. Frequency of T cell subpopulations. Percentages of T cells, B cells, NK cells, CD4+ T cells, CD8+ T cells and Tregs in B-hCLEC5A mice(C) were similar to those in BALB/c mice, demonstrating that humanization of CLEC5A does not change the frequency or distribution of these cell types in lymph node. Values are expressed as mean ± SEM. Significance was determined by two-way ANOVA test.  *P < 0.05, **P < 0.01, ***p < 0.0001.

Frequency of leukocyte subpopulations in bone marrow by flow cytometry. Bone marrow were isolated from female wild-type BALB/c mice and homozygous B-hCLEC5A mice(C) (n=3, 7-week-old). Flow cytometry analysis of the bone marrow was performed to assess the frequency of leukocyte subpopulations. Percentages of T cells, B cells, NK cells, dendritic cells, monocytes, macrophages and neutrophils in B-hCLEC5A mice(C) were similar to those in BALB/c mice, demonstrating that humanization of CLEC5A does not change the frequency or distribution of these cell types in bone marrow. Values are expressed as mean ± SEM. Significance was determined by two-way ANOVA test.  *P < 0.05, **P < 0.01, ***p < 0.0001.