Absence of circulating immune complexes containing DNA in hemodialysed sera

Although the presence of free DNA and antibodies to DNA in the sera of patients on maintenance hemodialysis has been reported, we found only a low incidence of antibodies to single-stranded DNA (ss-DNA) and native DNA (n-DNA) using an improved detection technique. In our search for evidence of the possible formation of DNA-anti-DNA circulating immune complexes (CIC), antibodies to n-DNA were detected in the sera of only 2 of 53 dialysed and 1 of 25 non-dialysed renal patients. CICs were detected in the sera of 17 of 53 dialysed (28% by Raji-RIA, 6% by Clq-BA) and 6 of 25 non-dialysed (20% by Raji-RIA and 24% by Clq-BA) renal patients: the difference is not significant (P greater than 0.25). DNase digestion of the dialysed sera that were positive for CIC by Raji-RIA produced no significant change in the results on re-assay (P greater than 0.50) in contrast with a significant decrease in CIC after DNase digestion of selected SLE sera and of solutions containing DNA-anti-DNA complexes formed in vitro (P less than 0.05). The formation of circulating DNA-anti-DNA complexes appears not to be the cause of the low incidence of antibodies to n-DNA in the sera of dialysed patients.