Microbial products induce autoimmune disease by an IL-12-dependent pathway.

The development and exacerbation of autoimmune diseases are associated with antecedent infectious illness. Microbial products such as LPS, bacterial DNA, or oligonucleotides containing an unmethylated cytosine-guanine dinucleotide have cytokine modulating properties. These products converted quiescent myelin basic protein-specific T cells into effector cells capable of transferring experimental allergic encephalomyelitis. The disease-promoting properties of the microbial products were solely dependent on their capacity to induce the production of IL-12.