Deoxyribonucleic acid-binding properties of human monoclonal anti-platelet antibodies obtained from patients with idiopathic thrombocytopenic purpura.

Recent studies of human monoclonal lupus autoantibodies have revealed that some of them are cross-reactive with platelets. To clarify further the bivalencies in anti-DNA and anti-platelet autoantibodies, we established nine human B cell lines producing monoclonal anti-platelet antibodies from patients with idiopathic thrombocytopenic purpura by Epstein-Barr virus transformation and studied the DNA-binding properties of these antibodies. Three of the antibodies showed cross-reactivity with single-stranded DNA (ssDNA), as determined by enzyme-linked immunosorbent assay and one of them was also found to bind to the synthetic polynucleotides; poly (dT) and poly (I), as well as to ssDNA. These findings suggest that cross-reaction between anti-DNA and anti-platelet antibodies is based on overlaps in specificity existing as common part of both autoantibodies.