Positivity Rates and Serum Levels of Antibodies Against Histone H3 Lysine 9 and Its Lactylated Form in Rheumatoid Arthritis and Its Mimics

Background/Objectives: To compare the positivity rates and serum levels of antibodies against histone H3 lysine 9 (anti-H3K9) and its lactylated form (anti-H3K9la) among patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), or Sjögren disease (SjD) and controls.

Methods

Serum anti-H3K9 and anti-H3K9la levels were measured by enzyme-linked immunosorbent assay from 93 patients with RA, 40 with SLE, 40 with SjD, and 40 controls. Antibody findings were compared across study groups and according to rheumatoid factor immunoglobulin M (RF-IgM) and anti-citrullinated protein antibody (ACPA) status in RA.

Results