McGowan, Eileen

Coronin‐1a is an evolutionarily conserved protein involved in rearrangements of the actin cytoskeleton. The expression of coronin‐1a is restricted to cells of the hematopoietic lineage. Microglia are resident immune cells of the central nervous system thought to have hematopoietic origins. The aim of this study was to determine if coronin‐1a could be used as a marker for detecting microglia in mammalian species. Using a polyclonal antibody and immunohistochemistry, we show that coronin‐1a is an effective marker for microglia in tissue culture and archival formalin fixed, paraffin embedded tissue, including a range of neurodegenerative and neuroinflammatory conditions and transgenic mice. In human, monkey, horse, rat and mouse tissue coronin‐1a immunoreactivity was present in cells with the morphology and distribution of microglia, even in sections that had been stored for long periods of time. The identity of coronin‐1a positive cells as microglia was confirmed with double immunolabeling for HLA‐DR and Iba‐1. Coronin‐1a immunoreactivity was also detected in T‐ and B‐lymphocytes in lymphoid tissue and neuroinflammatory conditions, but it was not expressed by astrocytes or oligodendrocytes. The results demonstrate that coronin‐1a is a novel marker for microglia in routinely processed tissue from normal and neurodegenerative conditions in both humans and animals.