Plasma glycosaminoglycans in systemic lupus erythematosus

The glycosaminoglycans (GAG) of plasma were assayed for uronic acid content in 13 female patients with systemic lupus erythematosus (SLE) and in healthy controls and compared with earlier results obtained in patients with rheumatoid arthritis (RA). The GAG were fractionated into a high charge "free" fraction known to contain chondroitin sulfate (CS) as a major and heparan-sulphate (HS) as a minor GAG and a low charge "bound" fraction known to contain low sulphated CS as the only GAG. The concentration of the free GAG was significantly increased in SLE (p less than 0.01); this increase was mainly due to the high concentrations of free GAG in patients with active disease. These patients also had an increased concentration of "bound" GAG (p less than 0.05). However, the plasma GAG concentrations did not correlate with the erythrocyte sedimentation rate, the binding of native DNA or the C4 concentration. Plasma proteoglycans and/or GAG are known to modulate certain immune functions. Whether the increase in free GAG reported here is somehow associated with the disturbed immunoregulation in SLE remains speculative.