The appearance of circulating antibodies to nuclear components (e.g. DNA, Histone, Nucleoprotein) is characteristic of SLE and may have pathogenic importance. But, it is not evident why these autoantibodies are produced. Concerning these immunological abnormalities, most research has concentrated on the humoral immune responses made against nuclear antigens. The role of cell-mediated immunity to unclear antigens in SLE has not been investigated. Therefore, the evidence of cell-mediated immunity to native calf thymus DNA was determined by MIT and LMIT in patients with SLE and normal subjects. The mean percent migration of MIT in SLE and normal subjects was 79.8±24.1 and 101.4±15.3%, respectively. The percent
migration below 70.8% was considered to be a positive test and 17 out of 42 patients with SLE had a positive test. In contrast, none of normal subjects did. These findings indicate that there is cellulay hypersensitivity to native DNA and peripheral lymphocytes of SLE patients produced a migration inhibitory factor (MIF) with responding to it. No correlation could be made between results of MIT and staining patterns of antinuclear factor (AMF), titers of anti-DNA antibody, serum complement levels and activity of the disease. The results of LMIT was differed from those of MIT. The mean percent migration of LMIT was not significantly different in SLE patients and normal subjects, and only a few cases in SLE exhibited a positive test. Considering the dissociation of these results in MIT and LMIT, the conclusion has been made that MIT is more useful in investigation the existence of cellular hypersensitivity. In addition, the role of T cells in the development of autoimmunity was discussed in accordance with the existence of cellular hypersensitivity to native DNA in SLE.