Detection of Tissue Macrophages in Different Organs Using Antibodies to the Microglial Marker Iba-1

Resident macrophages of different organs have structural and functional features, which can complicate their identification and analysis. A promising candidate for the role of a universal immunohistochemical marker of resident macrophages is the calcium-binding protein Iba-1, a well-known marker of brain microglia. The purpose of this work was to study the possibility of using one variant of antibodies to the Iba-1 protein for the immunohistochemical detection of resident macrophages in the liver, myocardium, lung, and choroid plexus of the rat brain. The study was performed on male Wistar rats (n = 15). It was shown that the use of rabbit monoclonal antibodies against Iba-1 allows highly effective detection of Kupffer cells in the liver, resident macrophages in the myocardium, alveolar and interstitial macrophages in the lung, and Kolmer cells in the choroid plexus of the rat brain. In all cases, the reaction is characterized by a high specificity and the absence of background staining. In contrast to the classical marker of macrophages, the CD68 molecule, the Iba-1 protein is evenly distributed in the cytoplasm of cell bodies and processes. This makes it possible to more fully identify cells using immunostaining for Iba-1, carry out their three-dimensional reconstructions, and study their structural and functional organization. Immunohistochemical reaction against Iba-1 can be successfully used as a universal alternative to other common methods for identifying resident macrophages.