Fibronectin in leprosy lesions: observations using monoclonal antibodies to human fibronectin.

Croystat sections of dermal lesions from 33 untreated patients with leprosy were studied by indirect immunofluorescence using monoclonal antibodies to human fibronectin. Macrophages in borderline (BL) and lepromatous (LL) leprosy showed intense staining with antifibronectin antibodies. In the tuberculoid lesions cells of the mononuclear phagocyte series in an epithelioid cell granuloma stained for fibronectin. The lymphocytes surrounding these granulomas also showed the presence of fibronectin. These results suggest that the granuloma of leprosy consists of macrophages expressing fibronectin and the lymphocytes in the lesion also appear to express this protein. In six borderline cases, the sub epidermal collagen band showed intense staining with antifibronectin antibodies. In addition, the distribution of Ia-like antigens and fibronectin was studied on the plastic adherent cells obtained from peripheral blood of 11 untreated patients with leprosy. Results indicate that higher percentage of adherent cells from lepromatous patients express fibronectin in comparison to adherent cells from tuberculoid patients or controls. However, no difference was observed in the expression of the Ia-like antigens by the adherent cells, from these patients.