RESUMEN
Systemic lupus erythematosus is a multisystemic autoimmune disease in which the kidneys are frequently involved. Clinical diagnosis of SLE is based on the criteria of American Rheumatism Association (ARA). A few cases who were classified as SLE by the ARA criteria but were antinuclear antibody (ANA)-negative have been reported. It was reported that critical factor in ANA positivity is the choice of substrate. It is generally accepted that the cultured cell of human origin, especially HEP-2 cell, is better than tissue section or animal cells. Thus, the ANA test is negative only in approximately 2M of SLE patients when human tissue culture cells are used as substrate. We report a 25-year-old man admitted to our hospital because of generalized edema. He was found to have active lupus nephritis(WHO class IV), photosensitivity and pancytopenia. The result of FANA test which used HEP-2 cell as substrate was repeatedly negative, but anti-ds DNA and anti-Ro antibody were positive.