Perivascular macrophages of rat liver do not express CD68 marker

BACKGROUND: Tissue macrophages play a key role in regulating hepatic tissue homeostasis. At the same time, they represent a heterogeneous population of cells in terms of both phenotypic and functional characteristics. AIM: To characterize the immunophenotype of rat liver macrophages using the phagocytic activity marker CD68 and the microglial marker Iba-1. METHODS: Liver and brain samples from Wistar rats (n = 8) were used. Double immunohistochemical staining was performed using antibodies against CD68 and Iba-1 (ionized calcium-binding adapter molecule 1). Specimens were analyzed using confocal laser scanning microscopy. RESULTS: Iba-1-positive cells identified in the specimens corresponded to interstitial macrophages and Kupffer cells. CD68- positive macrophages were detected along hepatic sinusoidal capillaries and between hepatocytes. Co-expression of CD68 and Iba-1 was observed in Kupffer cells in the liver and in perivascular macrophages in the brain, but not in perivascular macrophages localized in the portal triads or in the interlobular connective tissue. CONCLUSION: The colocalization of Iba-1 and CD68 in brain perivascular macrophages and the absence of their co-expression in hepatic interstitial macrophages indicate organ-specific phenotypic features of perivascular phagocytes.