The levels of total IgG (IgGt), subclasses IgG1, IgG2, IgG3, and IgG4, and IgA that were reactive with SAP were analyzed in the sera of 82 individuals with a proven E. histolytica infection and 24 subjects infected with E. dispar, both groups verified by stool PCR. Here, IGHG3 is linked to infection.