Possible approach for serodiagnosis of ascariasis by evaluation of immunoglobulin G4 response using Ascaris lumbricoides somatic antigen

Somatic antigen of Ascaris lumbricoides was purified to homogeneity (molecu lar mass, 34 kDa) by ammonium sulfate fractionation and successive chromato graphic procedures, namely, gel permeation, ion exchange, and high-performa nce gel permeation liquid chromatographies. The antigen showed strong bindi ng with immunoglobulin G (IgG) in Ascaris-infested patients;and was cross-r eactive with IgE and IgG in patients infested with other nematodes. It reac ted specifically with IgG4 (P < 0.001) in 63 Ascaris-infested patients, whi ch represented 65% of the total IgG response, though cross-reactivity with IgG1, IgG2, and IgG3 subclasses was observed, indicating the unique specifi city of this test system and its potential utility in the serodiagnosis of ascariasis.