Oral epithelial cell antifungal activity: approaches to evaluate a broad range of clinical conditions.

Anti-Candida activity by oral epithelial cells is considered one of several innate mucosal defense mechanisms against oropharyngeal candidiasis (OPC). OPC is the most common fungal infection in HIV disease. Previously we reported that oral epithelial cell anti-Candida activity is reduced in those with OPC, potentially representing a contributing factor to OPC. However, testing clinical epithelial cells possessing high levels of Candida has been limiting due to high background in the assay controls. HIV+ smokers often develop OPC sooner than non-smokers during progression to AIDS, suggesting additional immune aberrations. The purpose of this study was to design a means to reduce Candida associated with epithelial cells collected from saliva without affecting their in vitro growth inhibitory activity, and to employ that approach to evaluate antifungal activity in HIV+ smokers. To do so, oral epithelial cells with and without known levels of Candida were subjected to various treatments including azole, polyene, or echinocandin antifungal drugs or fixation followed by the standard growth inhibition (GI) assay. The results indicated that antifungal drugs, while effectively reducing cell-associated Candida, also affected epithelial cell function. In contrast, fixation with paraformaldehyde eliminated cell-associated Candida and had minimal effects on epithelial cell anti-Candida activity. Employing the fixation design that allowed a broad range of patients to be evaluated showed no difference in oral epithelial anti-Candida activity between HIV+ smokers and non-smokers. Therefore, oral epithelial cell antifungal activity does not appear compromised in those who smoke, reducing it as a contributing factor in susceptibility to premature OPC.