Identification of DNA-binding lymphocytes in patients with systemic lupus erythematosus

Abstract

Antigen-ginding lymphocytes capable of binding native DNA (DNA-ABC) were identified in the peripheral blood of normal controls and patients with systemic lupus erythematosus (SLE) by autoradiography with 125I-nDNA. 12 patients with active SLE had 404 +/- 273 (mean +/- SD) DNA-ABC/105 lymphocytes, while 7 inactive SLE patients and 13 normals had 120 +/- 48 and 48 +/- 36, respectively. All three groups were significantly different from one another (p less than 0.01). No significant correlation was detected between the quantity of anti-native DNA (nDNA) antibody and number of DNA-ABC; however, most patients with large amounts of anti-nDNA antibody had both active disease and large numbers of DNA-ABC. Numbers of DNA-ABC and lymphocytes with surface immunoglobulin (Ig) did not change significantly after an 18-h incubation at 37degreeC. After depletion of B-lymphocytes by passage over bead columns coated with a complex of IgG and anti-IgG, the great majority of DNA-ABC were removed in both normal subjects and SLE patients. Labeling lymphocytes sequentially with 125I-nDNA, followed by an indirect fluorescence technique for identification of surface Ig, indicated that the great mahority of radiolabeled cells had surface Ig by fluorescence microscopy in four normals (average 93%) and five patients with active SLF (average 82%). The predominance of nDNA-sensitive B-lymphocytes in the peripheral blood of both normals and SLE patients is consistent with the concept that the induction of the anti-nDNA antibody response is due to the stimulation of preexisting nDNA-specific B lymphocytes by mechanisms other than those necessarily involving participation of nDNA-specific T lymphocytes.