Catalytic DNA- and RNA-hydrolyzing antibodies from milk of healthy human mothers

Various catalytically active antibodies (Abs), or abzymes, have been detect ed recently in the sera of patients with autoimmune pathologies, in whom th eir presence is probably associated with autoimmunization. Normal humans ar e generally not considered to have abzymes, since no obvious immunizing fac tors are present. Here is shown by different methods that IgG from the milk of normal females possesses both DNase and RNase activities. The activitie s were also present in the IgG F(ab')(2) and Fab fragments. Affinity modification of IgG by the chemically reactive derivative of an ol igonucleotide led to preferential modification of the L chain of IgG. After separation of the subunits by sodium dodecyl sulfate electrophoresis in a gel containing DNA, an in-gel assay showed DNase activity in the L chain. T he L chain separated by affinity chromatography on DNA-cellulose was cataly tically active. These findings speak in favor of the generation of catalyti c Abs by the immune system of healthy mothers. It is known that the treatme nt of adults with DNases and RNases offers protection from viral and bacter ial diseases. Since breast milk protects the infants from infections until the immune system is developed, this raises the possibility that catalytic Abs like nucleases, may possess a protective role.