Expression of the costimulatory molecule CD86, but not CD80, in keratinocytes of normal cervical epithelium and human papillomavirus-16 positive low squamous intraepithelial lesions.

Keratinocytes have been traditionally considered as nonprofessional antigen presenting cells, since multipassaged cells from skin biopsies of healthy individuals do not constitutively express major histocompatibility complex (MHC) class II or costimulatory molecules, but can be induced to do so after exposure to interferon-gamma. In normal and human papillomavirus (HPV)-infected cervical epithelium, keratinocytes are affected by a variety of soluble mediators that could modulate the expression of molecules including costimulatory proteins; however, the presence of these molecules within the cervix has been poorly studied. Therefore, our aim was to further explore the presence of costimulatory molecules on normal cervical epithelium and HPV-16 positive low squamous intraepithelial lesions (LSIL). We found in situ CD86 (but not CD80) displayed on the surface of normal keratinocytes from the spinous layer of human cervical epithelium. The presence of the protein and its messenger RNA level (evaluated by in situ hybridization) was diminished in HPV-16 positive LSILs. Although downregulation of costimulatory molecules is frequently related to cytokines expression, we did not observe differences in the presence of interleukin-10, the main cytokine that inhibits CD86 expression. Expression of CD86 on keratinocytes from normal cervical epithelium could indicate the potentiality of these cells to activate cytotoxic T cells, while the shut-off of this molecule in HPV-16 positive lesions could be a mechanism for evading host immune surveillance, resulting in the persistent HPV infection and probable progression of cervical lesions.