Oral keratinocyte immune responses in HIV-associated candidiasis

Candidiasis is the most commonly encountered opportunistic infection among HIV-positive subjects. The purpose of this study was to assess specific keratinocyte immune parameters in the pseudomembranous and erythematous forms of HIV-associated oral candidiasis.

This collaborative study from three centers analyzed 25 HIV-positive and 10 HIV-negative subjects with either pseudomembranous or erythematous candidiasis. Oral biopsy specimens from lesional tissues were procured, and histopathologic features were correlated with immunohistochemical and in situ hybridization investigations for the expression of interleukin 1 alpha, interleukin 8, antimicrobial calprotectin, lymphocyte populations, and Candida antigen.

Both pseudomembranous and erythematous candidiasis among HIV-infected subjects showed a mild interface lymphocytic mucositis with the presence of neutrophilic subcorneal abscesses in the latter. Erythematous candidiasis cases that failed to show surface mycelia, did yield positive results for Candida antigens in the parakeratinized layer. The expression of inflammatory chemokines were positive in all groups and calprotectin appeared to serve as a keratinocyte barrier to hyphal penetration.

The erythematous form of candidiasis is often devoid of hyphae yet the presence of Candida antigens in the surface epithelium implicates an immune or allergic process. The intactness of chemokines and antimicrobial calprotectin in keratinocytes may explain why disseminated candidiasis is rarely encountered in HIV-infected patients.