Characteristics of antinuclear factors in felty's syndrome

Antinuclear factors in the sera of 8 patients with Felty's syndrome were studied by various immunologic technics. All sera showed antinuclear factor activity. However, antinuclear factors in Felty's sera did not fix human complement, while antinuclear factors in 9 out of 10 control sera from patients with systemic lupus erythematosus did. This difference could be explained neither by a difference in antinuclear factor titer of the IgG class, nor by a blockage of complement fixation by rheumatoid factor. The findings of other investigators and the possible significance of antinuclear factor complement fixation are discussed.