CD36 (OKM5) antigen expression on human mucosal epithelia is associated with keratinization type

The glycoprotein CD36 functions as a thrombospondin receptor and is expressed on a variety of cell types, including platelets, monocyte/macrophages, and endothelial cells. In human skin, the presence of CD36 on keratinocytes was initially found in lesional areas of T-cell mediated inflammatory dermatoses. Controversy still exists on the interpretation of this expression as an inflammatory or differentiation-associated marker. So far, only limited data are available on CD36 expression in oral epithelia. The present immunohistochemical study was therefore performed to determine the presence of CD36 on keratinocytes of healthy and disease-affected epithelia of the oral cavity in 80 biopsy specimens. As results, we found an inflammation-independent strong expression of CD36 in oral epithelia with ortho- and parakeratinization, such as the oral side of the gingiva, the hard palate, and the back of the tongue. Non-keratinized epithelia such as the gingival pocket epithelium, the soft palate, the lip, the buccal mucosa, and the side of the tongue were CD36 negative. We therefore suggest that CD36 expression in keratinocytes from oral epithelia is an epithelial differentiation marker.