Preferential secretion of a common anti-DNA idiotype (16/6 Id) and anti-polynucleotide antibodies by normal mononuclear cells following stimulation with Klebsiella pneumoniae

Peripheral blood mononuclear cells derived from 6 normal subjects were incubated with 5 polyclonal activators (pokeweed mitogen, Epstein-Barr virus, group-A Streptococcus, Staphylococcus aureus and Klebsiella pneumoniae. After 7 days of incubation, the supernatants were examined for immunoglobulin (IgG and IgM) production, the level of a common anti-DNA idiotype (16/6 Id) and autoantibody activity against ssDNA, dsDNA, poly(I), poly(dT) and cardiolipin. Significantly increased levels of the 16/6 Id were recorded only with the Klebsiella stimulated MNC. Increased immunoglobulin levels and autoantibody reactivity were noted with all 5 polyclonal activators. The Klebsiella cell membrane preparation induced the highest values. No correlation was found between the 16/6 levels, autoantibody activity and the absolute concentrations of IgG or IgM. This study, together with previous reports, suggests a role for Klebsiella in the etiology of autoimmune diseases. We suggest that Klebsiella can induce anti-DNA-like autoantibodies not only by polyclonal activation, but also by a more specific stimulus.