Allo-anti-C in a patient who had previously made an autoantibody mimicking anti-C

A patient, previously studied by us, who had produced a benign autoantibody with a specificity that mimicked anti-C, has now produced allo-anti-C that is not of the mimicking type. She is no longer producing any serologically demonstrable autoantibody. It is highly probable that conversion from auto to alloantibody production in this patient was prompted by the introduction of additional foreign immunogen on fetal red blood cells during her third pregnancy.