Special Topic Issue: International Archives of Allergy and Immunology 2000, Vol. 121, No. 1 In 1948, the observation of LE cells in a patient with systemic lupus erythematosus (SLE) triggered the discovery of a broad variety of autoantibodies directed to nuclear antigens, called antinuclear antibodies (ANA). Nowadays, different ANA serve as important diagnostic parameters for differentiating most of the connective tissue diseases, including SLE, neonatal lupus syndromes, Sjögren‘s syndrome, scleroderma, autoimmune myositis, mixed connective tissue disease, and other overlaps. This special issue summarizes the history of ANA and the methods for their detection as well as special topics of ANA-related diseases. Furthermore, the pathogenic role of these autoantibodies in targeting non-organ-specific intracelllular antigens as a functionally important constituent of a subcellular particle or multimolecular complex is addressed. Notably, some of these autoantibodies have served as significant tools for cell biologists in elucidating the subcellular structures and functions of autoantigens. A valuable single source of information, this publication will interest clinical and laboratory immunologists, rheumatologists, cell biologists, dermatologists, and specialists in internal medicine and neonatology.