A common anti-DNA antibody idiotype and anti-phospholipid antibodies in sera from patients with schistosomiasis and filariasis with and without nephritis

The serum concentration of a public idiotype (16/6 ID), originally identified on a human hybridoma-derived monoclonal anti-DNA antibody, was raised in patients with S. mansoni and filariasis with or without nephritis, compared to patients with S. haematobium (in which nephritis does not occur) or idiopathic nephritis not associated with infection. There was no significant difference in 16/6 ID levels between patients with or without renal disease, whether associated with S. mansoni or filarial infection. The 16/6 ID-positive antibodies did not bind to native or denatured DNA, using competitive fluid-phase inhibition studies. Anti-cardiolipin antibody (ACA) concentration was increased in patients with either S. mansoni or filarial infection. In filariasis, both IgG and IgM ACA isotypes were elevated, irrespective of the presence of nephritis. In S. mansoni infection, IgA ACA were limited to patients with renal disease, and IgG ACA isotype to patients without overt nephritis. Both isotypes of anti-cardiolipin antibody correlated with levels of the 16/6 ID in patients with S. mansoni or filariasis. The 16/6 idiotype was therefore a feature of chronic helminthic infection, but was not related to anti-DNA antibody levels or specificity. The occurrence of nephritis as a complication of these infections was not related to the prevalence of the 16/6 idiotype.