Primary Biliary Cirrhosis-Specific Antimitochondrial Antibodies in Neonatal Haemochromatosis

Figure 3

Antigen specific anti-mitochondrial antibody (AMA) reactivity in the infant and his mother tested by ELISA. Optical density (𝑦-axis) and time elapsed since birth of child (𝑥-axis) are indicated.

(a) The AMAs present in these samples are predominantly directed against the E2 subunit of pyruvate dehydrogenase complex (PDC-E2), which is the major AMA autoantigen in patients with primary biliary cirrhosis. Antibody reactivity to the E2 subunits of branched chain oxoacid dehydrogenase complex (BCOADC-E2) and oxoacid dehydrogenase complex (OGDC-E2), which are also immunodominant antigens, is not detectable. The dashed line represents the cut-off of 0.24 (mean average+5 standard deviations) of 28 normal controls tested in triplicate

(b) Anti-PDC-E2 IgG subclasses are similarly distributed in the infant and his mother, with predominance of IgG3 and IgG1. The mother’s serum also contains anti-PDC-E2 of IgG4 type, which does not cross the placenta

(c) Anti-PDC-E2 antibodies declined in titre over time and were well below the cut-off value in both mother and infant 10 months after delivery