Restrictions among heavy and light chain determinants of granulocyte-specific antinuclear factors

Abstract

In fifty-five rheumatoid arthritis sera with positive granulocyte-specific antinuclear factors (GS-ANF) tests were made to further characterize these antibodies. All sera contained GS-ANF of the IgG class and most of the sera also of the IgM and IgA classes, whereas only about 10 per cent of the sera contained GS-ANF of the IgD class. Most of the sera contained GS-ANF carrying both κ and λ light chain determinants, but in five cases only one of the light chain subclasses could be found.

The distribution of the GS-ANF among the four subclasses of IgG showed marked variations. From one to three subclasses could be lacking or noticeably depressed. There was no predominance of any one or two subclasses. Complement (C₃) fixing properties correlated with GS-ANF of the IgG₁ and/or IgG₃ subclasses. These properties make the GS-ANF interesting as possible pathogenic factors in rheumatoid arthritis.

Some evidence is presented that the GS-ANF may be directed against several different antigens in the polymorphonuclear granulocyte nuclei.