[Expression of HLA-DR, DP, DQ antigens in fibrous sino-nasal polyps]

In the last years nasal polyps have been studied by several authors with different methodologies; however, their etiology is still unclear. In this paper we have analyzed in four nasal polyps of fibrous type, the HLA class II (HLA-DR, DP, DQ) molecule expression by means of immunohistochemical techniques (immunoperoxidase and immunophosphatase). A strong inflammatory cell infiltration, a percentage increase of both HLA-DR+ and HLA-DQ+ cells (normal nasal mucous membrane stroma infiltrating cells: DR+ < 40%, DP+ < 2%, DQ+ < 3%; fibrous polyps infiltrating cells: DR+ = 68%, DP+ < 2, DQ+ = 7%) as well as a clear positivity for DR expression of both surface and glandular epithelia were observed in all polyps. Furthermore, in the stalk area of one of the studied polyps DR+DQ+ cells with macrophagic features and having tight. connections with the vessels were observed. The scanty vascularization with the presence of activated mononuclear and mast cells might be responsible for polyp growth by locally producing an anomalous concentration of growth factors.