[Anti-A/B-IgM/G immune response to accidental A-O transfusion and to Toxocara canis infestation].

We have applied a sensitive and reproducible AB0-ELISA, in combination with a hemagglutination test, for the study of class- and subclass specific humoral immune response in the AB0 system upon challenge by the intravenous route (A-type blood in a 0-recipient) and by helminthic A and B blood group antigen (Toxocara canis). After accidental transfusion, peak booster concentrations of anti-A-IgG reached 411 micrograms per g total IgG, with IgG1 and IgG2 subclasses evenly distributed. With Toxocara canis immunity, anti-A/B-IgG rose to 244 and 382 micrograms/g IgG, nearly 100% over the mean value of 15 healthy blood donors; it is noteworthy that these IgG levels almost exclusively consisted of IgG1. Both observations suggest that unusual presentation of A antigen to host leads to a predominant if not exclusive IgG booster reaction.