Secondary Sjögren's syndrome and chromosome six markers.

Patients with Sjögren's syndrome (SS) in association with either Rheumatoid Arthritis (RA), Systemic Lupus Erythematosus (SLE) or Sclerodactyly were tested for HLA-A, B and Dr antigens and the phenotypes of the 4th component of complement (CA). Significant associations were identified between HLA-Bw62, Dr4, C4B2.9, C4A8 and females with SS-RA. The MHC antigen frequencies noted for secondary Sjögren's syndrome differed from those reported for their respective primary diseases and the implications of these observations are discussed.