Immunohistochemical aspects of apoptosis in subcutaneous lupus erythematosus

Lupus erythematosus (LE) has a broad clinical spectrum from exclusively skin damage (chronic discoid lupus-DLE or subacute lupus erythematosus-SCLE) to systemic, multiorgan disease (involving skin, joints, kidney, central nervous system). LE is characterized by an autoimmune component. SCLE is characterized by erythemato-squamous lesions mainly in photoexposed areas. Apoptosis (programmed cellular death) is essential for normal embryogenesis and for normal tissue homeostasis and control. Inefficient apoptotic cell clearance has been correlated with inflammatory diseases and autoimmunity outburst. This study evaluates histological and immunohistochemical expression ofpro-apoptotic markers in patients with SCLE.

20 patients with SCLE and 10 healthy controls were selected. Biopsies from skin lesions were performed. Biopsies were evaluated for immunohistochemical expression of caspase 3, CD25, CD35, CD21, CD36, CD68, CD31, IgM detection, T and B cell markers.

In the inflammatory cells population we distinguished T lymphocytes, rare B lymphocytes, dendritic cells and macrophages. Within the lymphocyte population IL-2 receptor (CD25) expression was low but caspase 3 expression was intense in lymphocytes, epithelial cells and pericytes. Basal epithelial vacuolations were common. Phagocytic-cell and lymphocytic expression of CD35 (complement receptor 1-CR1) and CD21 (complement receptor 2-CR2) were lower when compared to healthy controls.

In SCLE patients we observed lymphocytic, epithelial and pericytal cell apoptosis and CR1 and CR2 expression are lower in professional phagocytes, suggesting a delay in the uptake of apoptotic bodies.