Development of two novel microglia-specific monoclonal antibodies to discriminate microglia from other CNS-resident macrophages by flow cytometry

Abstract

Although microglia are the predominant resident macrophages of the central nervous system (CNS), other macrophages can be found in the CNS. As both populations express CD11b, microglia are generally distinguished from peripheral macrophages by lower expression of CD45. This can introduce bias in the analysis of flow cytometric data and make cell sorting challenging. Other microglia associated markers such as Aif1/Iba1 are less cell specific and therefore of limited use to dissect microglia from other brain residing macrophages. Recent single cell transcriptome studies have identified more specific signature genes of microglia, including surface molecule Tmem119 and transcription factor Sall1.

To allow robust discrimination between microglia and other brain resident/infiltrating macrophages based on the expression of a single marker by flow cytometry, we have developed monoclonal rat antibodies against mouse Tmem119 and Sall1, respectively. Both clones, V3RT1GOsz (Tmem119) and NRNSTNX (Sall1), were validated by flow cytometric analysis of fresh mouse brain. Here we show that both antibodies can be used to distinguish microglia from other macrophages by flow cytometry without reliance on CD11b or CD45 expression. The availability of these specific antibodies against microglia signature molecules will contribute significantly to the ability to isolate mouse microglia and their advanced characterization.