Platelet-associated DNA and anti-DNA antibody in systemic lupus erythematosus with nephritis

We report DNA and specific anti-dsDNA antibody (dsDNAb) in excess of controls, associated with platelets from 35 patients with systemic lupus erythematosus (SLE). Deoxyribonuclease (DNase) treatment of intact platelets resulted not only in a drop in platelet-associated DNA, but also a dramatic fall in platelet-associated dsDNAb. This suggests that at least some DNA and virtually all the dsDNAb is bound to the platelet surface, probably in the form of an immune complex. The quantity of platelet-associated DNA did not correlate with amounts of platelet-associated anti-dsDNA antibody (PAdsDNAb); perhaps because platelets also have receptors for DNA itself. Total platelet-associated IgG was elevated in only six patients with normal PAdsDNab.