In the case of a prenatal sample showing an anti-M reactive with polyspecific AHG, what testing can determine clinical significance?

Testing with DTT (dithiothreitol) treated serum provides a specific approach to evaluating the clinical significance of an anti-M antibody in prenatal samples. The rationale behind this test revolves around the fact that DTT is known to reduce disulfide bonds, which can eliminate certain antibodies, particularly IgM, while leaving IgG antibodies intact.

In the context of an anti-M antibody, it's crucial to determine if it is an IgM or IgG antibody, as only IgG antibodies are associated with significant clinical implications in pregnancy, including hemolytic disease of the newborn (HDN). By treating the serum with DTT and then retesting, one can assess whether the antibody persists. If the reactivity is lost post-DTT treatment, it suggests that the antibody is likely an IgM, which generally does not cross the placenta and therefore is not clinically significant in terms of fetal impact. On the other hand, if the reactivity remains, it indicates the presence of an IgG antibody, which is clinically significant.

The other testing methods mentioned can provide various insights but do not directly assess clinical significance as effectively as DTT treatment. For instance, using IgG AHG can help determine the isotype of the antibody but does not