Anti CD163+, Iba1+, and CD68+ Cells in the Adult Human Inner Ear: Normal Distribution of an Unappreciated Class of Macrophages/Microglia and Implications for Inflammatory Otopathology in Humans.
OBJECTIVE
Identification, characterization, and location of cells involved in the innate immune defense system of the human inner ear may lead to a better understanding of many otologic diseases and new treatments for hearing and balance-related disorders.


BACKGROUND
Many otologic disorders are thought to have, as part of their disease process, an immune component. Although resident macrophages are known to exist in the mouse inner ear, the innate immune cells in the human inner ear are, to date, unknown.


METHODS
Primary antibodies against CD163, Iba1, and CD68 (markers known to be specific for macrophages/microglia) were used to immunohistochemically stain celloidin embedded archival temporal bone tissue of normal individuals with no known otologic disorders other than changes associated with age.


RESULTS
Cells were positively stained throughout the temporal bone within the connective tissue and supporting cells with all three markers. They were often associated with neurons and on occasion entered the sensory cell areas of the auditory and vestibular epithelium.


CONCLUSIONS
We have immunohistochemically identified an unappreciated class of cells in the normal adult inner ear consistent in staining characteristics and morphology with macrophages/microglia. As in other organ systems, it is likely these cells play an essential role in organ homeostasis that has not yet been elucidated within the ear.
Jennifer T
JT
O'Malley
Joseph B
JB
Nadol
Michael J
MJ
McKenna
D000199:Actins / Q000378:metabolism; D000328:Adult; D015703:Antigens, CD / Q000378:metabolism*; D015214:Antigens, Differentiation, Myelomonocytic / Q000378:metabolism*; D015415:Biomarkers; D002135:Calcium-Binding Proteins; D003238:Connective Tissue / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D007758:Ear, Inner / Q000166:cytology* / Q000378:metabolism*; D004848:Epithelium / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D008264:Macrophages / Q000378:metabolism*; D008840:Microfilament Proteins; D017628:Microglia / Q000473:pathology*; D010031:Otitis / Q000473:pathology*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D013701:Temporal Bone / Q000166:cytology / Q000378:metabolism; D014722:Vestibule, Labyrinth / Q000166:cytology / Q000378:metabolism; D000098902:CD163 Antigen; D000097382:CD68 Molecule
D000199:Actins; D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D015415:Biomarkers; D002135:Calcium-Binding Proteins; D004268:DNA-Binding Proteins; D008840:Microfilament Proteins; D011956:Receptors, Cell Surface; D000098902:CD163 Antigen; C541116:ACTA2 protein, human; C112986:AIF1 protein, human; C067980:CD68 antigen, human; D000097382:CD68 Molecule