Evidence for relationships between antiperinuclear and IgG rheumatoid factor.

Antiperinuclear factor (APF) and IgG-rheumatoid factor (IgG-RF) has been found in 64% and 48% of cases of rheumatoid arthritis, 36% and 50% of cases of psoriasis and 31% and 45% of cases of primary Sjögren's syndrome. A close relationship between APF and IgG-RF is suggested by statistical and experimental data. Purified IgG-RF has some degree of APF activity.