Expression of HLA class II antigens in marginal periodontitis of patients with Down's syndrome.

The expression of HLA Class II antigens on the surfaces of immunocompetent cells and the presence of CD1a+ cells (Langerhans cells) are important components of antigen presentation. Quantitative variations in HLA class II expression on antigen-presenting cells play a role in immune regulation. An indirect immunofluorescent technique was used on cryostat sections to reveal such differences qualitatively or quantitatively between chronic marginal periodontitis (CMP) in patients with Down's syndrome (DS) and in otherwise normal patients (NP). We found increased frequency of HLA Class II (HLA-expression on inflammatory cells and on keratinocytes of the oral gingival epithelium) in CMP of DS patients compared to sections from NP. The expression of HLA-DR was more frequent on the keratinocytes of the pocket epithelium in NP than in DS. There were significantly higher numbers of CD1a+ cells and ratios of HLA-DR+/CD1a+ cells and HLA-DP+/CD1a+ cells in the DS group compared to the NP group. Our conclusion is that there is a more pronounced inflammatory process in the gingival sites with CMP of DS patients compared to CMP in NP. The findings also indicate that there is a highly activated immune response in CMP of DS patients.