Fibroblast-Lymphocyte-Macrophage Interaction in Erythema Nodosum-like Lesions of Behcet’s Syndrome: An Ultrastructural Study
In this study biopsy specimens of erythema nodosum-like lesions from eighteen patients with Behfet's syndrome were examined with the electron microscope to elucidate the close relationship between lymphocytes and/or macrophages and fibroblasts in the perivascular regions of the dermis and subcutaneous fat accompanied by prominent edematous changes and extensive depletion of collagen fibers. Electron microscopic evaluation revealed lymphocyte emperipolesis as a special pattern of adhesion of lymphocytes to fibroblasts in 3-4 days after the onset of the skin lesions. The emperipoletic lymphocytes as well as the lymphocytes adhering to fibroblasts contained a number of polyribosomes and few organelles in the cytoplasm. The fibroblasts with these lymphocytes showed remarkable development of rough endoplasmic reticulum and any other cytoplasmic organelles, indicating activated cellular function as collagen synthesis. Adhesion of lymphocytes to fibroblasts was followed by adhesion to macrophages. In the triads of lymphocyte-fibroblast-macrophage, morphological profiles of the fibroblasts showed involutional changes suggestive of suppressed cellular function through their cytoplasmic lobulation. Our findings indicate that fibroblasts are regulated directly by adhesion of lymphocytes and/or macrophages in fibrous repair of the erythema nodosum-like lesions of Behcet's syndrome.