Phenotypic characterization of CD7 expression on mouse immune cells using a novel monoclonal antibody 2294

Abstract Description CD7 is a transmembrane glycoprotein belonging to the immunoglobulin superfamily. In humans, CD7 is expressed on a majority of peripheral blood T cells and NK cells, and is implicated as a biomarker and CAR target for some hematopoietic malignancies. Mouse and human CD7 share 43% amino acid sequence similarity; structurally, they differ by the absence of a “stalk region” in mouse CD7. Currently, the sparsity of commercially available reagents to detect mouse CD7 coincides with much unknowns of its expression and function. Recently, we have successfully developed a novel monoclonal antibody (mAb) that specifically recognizes mouse CD7. To our knowledge, this would be the first commercially available anti-mouse CD7 mAb for flow cytometry. Using this antibody, we examined the expression of CD7 in mouse lymphoid organs by flow cytometry and CITE-Seq. At the mRNA level, our single-cell sequencing results are consistent with published data. At the protein level, mouse CD7 is expressed on subsets of T cells, with a higher percentage in γδ T cells than αβ T cells, a subset of NK cells, macrophages, and dendritic cells, but not on mature B cells, uncovering a distinct expression pattern from human CD7. We also show CD7 expression dynamics over age, during T cell thymic development, as well as after in vitro T cell activation. This study proves the new mAb as a useful novel tool in CD7 research, and provides initial mouse CD7 protein expression profiling data. Topic Categories Lymphocyte Differentiation and Peripheral Maintenance (LYM)