Fig 1: Antibodies against Stx2 and Stx1.Representative immunoblot strips from HUS or healthy children plasma reactive to Stx2 (A) and Stx1 (B) are shown. A) Lane 1 shows a mouse-polyclonal plasma reactive against Stx2 A and B subunits; positive human plasma showed reactivity to either the A subunit alone (lane 2), the B subunit alone (lane 3), or both subunits (lane 5). Samples that showed a complete absence of binding signal were considered negative (lane 4). B) Lane 1 shows a mouse-polyclonal plasma reactive against Stx1 A subunit, and lane 5 shows a monoclonal hybridoma reactive against Stx1-B subunit (13C4, ATCC CRL-1794). Positive human plasma showed Stx1-binding signal to either the A subunit alone (lane 2) or both subunits (lane 4). Samples that showed a complete absence of binding were considered negative (lane 3). Each plasma sample was assayed at least twice. When discrepancy between the results was observed, a third WB was made in order to rule out the wrong result.