Antinuclear Antibodies—Attempts at Ultrastructural Localization ∗

Considerable interest has evolved over the last 10 years concerning the raison d'être as well as the pathogenic significance of antinuclear antibodies among human disease states. The elution from isolated lupus glomeruli of antibodies showing distinct anti-DNA or anti-nucleoprotein reactivity (1-3) has produced strong evidence that these γ-globulins may participate as part of antigen-antibody complexes localizing within glomerular lesions. Recently, by use of human antibodies to DNA and immunofluorescent procedures, it has been shown that DNA itself is present within some glomerular lesions as the possible antigenic contribution to pathogenic complexes (4). Moreover, eluted γ-globulin from lupus glomeruli was shown by these same workers to contain marked concentrations of antibody activity for various nuclear antigens.

The present study was primarily directed at an electron microscopic localization within the nucleus of high titered antinuclear antibodies using sera from patients with active disseminated lupus erythematosus (SLE). Ferritin-labeled γ-globulin fractions from sera with strong reactivity for nuclear antigens were employed.

Materials and Methods. Sera from 38 patients with disseminated lupus erythematosus were collected and stored in frozen aliquots at −20°C until fractionation and antibody assay procedures were undertaken. Of the 38 patients'sera studied, only 6 showed consistently broad enough antinuclear reactivity to be deemed worthy of attempts at antinuclear localization. A profile of the multiplicity of reactivities for various nuclear antigens is shown in Table I. Agglutinating antibodies for latex particles coated with nucleoprotein (5,6), precipitins for nucleoprotein (7) and the nuclear antigen previously designated as SM antigen by Tan and Kunkel (8), immunofluorescent antinuclear reactivity against nuclei seen in 6-μ sections of mouse kidney (8), and complement fixation for nucleoprotein, SM antigen and DNA (8-10) were studied.

In addition, because of previous work by others (11-13) indicating presence of 7S γM within some sera from patients with SLE, sucrose density gradient separations (14) of 0.3 ml of serum diluted 1:1 with 0.15 M NaCl were performed.