However, the antibody response against the Stx2 B subunit tends to decrease faster than the antibody response against Stx2 A subunit. In fact, not only the frequency of anti-Stx2 B antibodies decreased in HUSrec patients, but also their ELISA titer decreased over time. Consequently, HUSrec group showed an increased frequency of positive samples for the A subunit compared to the NHC group, while there were not differences in the frequency of positive samples for the B subunit. These findings strengthen the need for investigating individual samples sequentially. Although the biological significance of antibodies against both Stx2 subunits is not known and requires further study, recent evidence suggests that specific antibodies for Stx2 A subunit may be important for protection. In fact,CPI-613 monoclonal antibodies directed to the Stx2 A subunit have been proved to be as protective or more than those directed to the B subunit. Although the involved mechanisms are still a matter for discussion, it has been recently reported that anti-Stx2 A subunit antibodies interfere with the retrograde transport of the toxin, and may interact with Stx2 when it is still bound to membrane receptors. In addition, antibodies directed to Stx2-A subunit as opposed to those directed against the B subunit, have broadspectrum activity that includes other Stx2 variants, such as Stx2c. In conclusion,CUDC-907 this is the first report describing seroepidemiological data about anti-Stx antibodies in the pediatric Argentinean population, this is in healthy and HUS-suffering children, through accurate and sensitive techniques such as ELISA and WB. This information not only could provide comprehensive immunological data as a basis for future immunization schedules to Stx, but also encourage laboratories from the National Health Surveillance System to standardize both techniques in order to evaluate a bigger population that include individuals from areas with different incidence of HUS. Fibrin D-dimer, the most commonly used clinical assay of coagulation activation and in vivo fibrin formation and lysis in circulating blood has been associated with increased risk of cardiovascular disease.