DNA fragments of around 200 base pair (average size) have been covalently crosslinked with 8-methoxypsoralen under 365nm UV light. The photoadduct, induced antibodies in rabbits with a titer of >1:12, 800 by direct bindng ELISA. Binding data showed that the induced antibodies are conformation-specific recognizing restricted conformational change at site of crosslinking. Human autoantibodies against DNA, bound not only to native DNA but to the photomodified DNA fragment as well. In addition, binding patterns of SLE sera obtained from different patients were remarkably similar, indicating the recognition of altered conformation of the modified polymer by naturally occurring SLE anti-DNA autoantibodies.