The RB6-8C5 monoclonal antibody reacts with the mouse Ly-6G (also known as Gr-1). The Ly-6G protein is a myeloid differentiation antigen of 21-25 kDa, expressed in a regulated manner by the myeloid lineage in the bone marrow, where the level of antigen expression is correlated with the granulocyte maturation and differentiation. In the bone marrow, the antigen is not expressed by the erythroid cells.

From the peripheric cells, RB6-8C5 binds with monocytes, neutrophils and eosinophils.

As a marker for the mouse monocytes, macrophages and granulocytes, the RB6-8C5 antibody is usually combined with M1/70, a macrophage labeling antibody (Anti-CD11b), for phenotypic analysis.