Quantitative analysis of OX62-positive dendritic cell distribution in the rat laryngeal complex.

Objectives: Dendritic cells (DCs) are key instigators of rejection after transplantation. Their distribution has not been systematically characterized in all locations of the larynx and its surrounding tissues.

Methods: Rat larynges were stained with monoclonal antibodies identifying DCs. These cells were then enumerated by a new combination of techniques including immunofluorescence, confocal microscopy, and imaging software.

Results: The vast majority of DCs were located in the epithelium and subepithelium of the airway; the mean DC density ranged from 9 cells per square millimeter (0.2% of cells) to 645 cells per square millimeter (10.3% of cells). Their density in the epithelium was 3 to 11 times higher than that in the subepithelium. Non-airway sites (thyroid, parathyroid, muscle, fat) had mean DC densities varying from 3 cells per square millimeter (0.2%) to 57 cells per square millimeter (0.8%). No DCs were detected in cartilage.

Conclusions: Dendritic cells are concentrated in the laryngotracheal epithelium and subepithelium and represent a much smaller proportion in the other sites studied. A baseline for laryngeal DC population studies has been established, and a computerized model for consistent quantitation using confocal microscopy has been developed. This unique method will serve as a foundation for investigating DC trafficking after rat laryngeal transplantation.