Studies of anti‐f(ab')₂ antibodies and possible immunologic control mechanisms in systemic lupus erythematosus

Abstract

Studies of anti‐DNA and anti‐F(ab')2 antibodies were performed by enzyme‐linked immunosorbent assay in 51 patients with systemic lupus erythematosus (SLE). Patients with severe, uncontrolled disease showed high levels of anti‐DNA and low levels of anti‐F(ab')2 antibodies. Patients with quiescent SLE usually showed high levels of anti‐F(ab')2 and low levels of anti‐DNA antibodies. Isolated anti‐F(ab')2 antibodies from autologous SLE remission serum or from the sera of unaffected siblings of SLE patients showed maximum inhibition in test systems using affinity‐purified SLE anti‐DNA antibodies reacting with single‐stranded DNA.

Pathogenic anti-DNA idiotype-reactive IgG in intravenous immunoglobulin preparations

“…The preliminary ELISA included analysis of both anti-DNA and anti-F(ab')i levels by using previously described methods [24,25], Binefly. microtitre plates were separately coated with 1 ^g/mlofcalfthymusdsDNAand 5//g/mlof purified F(ab'); fragment obtained from pepsin-digested human IgG (Cohn fraction II).…”

“…Thus, 70 mg of each IVIG lot were first absorbed with DNA-Sepharose to remove any possible anti-DNA activity [24]. and then passed over a column of DNA-absorbed IgG (derived from Cohn fraetion II) by using a recycling pump in order to deplete both anti-F(ab')2 and anti-Fc reactivities.…”

“…20, 40, and 80/(g/ml)or eacheluaiein the final volume of 2 35 ml of PBS. Residual anti-DNA affinity of these preparations was subsequently defined by ELISA as previously described [24]. Parallel control tests were installed to evaluate the inhibiting properties of both eluates on purified anti-tetanus toxoid IMIG from preparation no.…”

Self Ig peptides: Key players in sustaining autoimmunity to dsDNA

“…12 In this area, reduction in titer of such negative regulatory molecules could have a stimulatory effect of anti-dsDNA antibody production. Indeed Silvestris et al 11 have found an inverse relationship between anti Fab 2 (which contain antibody to anti-dsDNA) and antidsDNA titers suggesting a regulatory role for the antiidiotypes to anti-dsDNA antibodies.…”

“…Alternatively, epitopic peptides of these surrogate molecules, administered in soluble form, could induce speci®c tolerance and have an inhibitory effect on anti-dsDNA production. Also in the inhibitory class would be anti-idiotypes for anti-dsDNA, which have been shown to exist in normal individuals 11 and in certain lupus patients who produce anti-LaaSSB, anti-RoaSSA andaor anti-U 1 RNP, subsets of which have anti-idiotype speci®-city for anti-dsDNA molecules. 12 In this area, reduction in titer of such negative regulatory molecules could have a stimulatory effect of anti-dsDNA antibody production.…”