Evaluation by the skin prick test of Anisakis simplex antigen purified by affinity chromatography in patients clinically diagnosed with Anisakis sensitization.

Anisakis simplex crude extracts (CE) (IPI, ASAC and ALK-ABELLO), A. simplex larval antigens purified using a column of IgG anti-A. simplex (PAK) or a column of IgG anti-Ascaris suum (PAS), antigen eluted from columns of IgG anti-A. suum (EAS) and an A. suum adult CE were assayed by the skin prick test. Thirty percent of assayed patients showed a negative reaction in the Anisakis skin prick test. Of 70% positives, two patients had a weal greater than that produced by histamine with the A. simplex extract from ABELLO and IPI. The A. suum skin prick test was positive in 35% of patients, with a lower reaction than that observed with the A. simplex extract from IPI in 57% of the sera and a higher reaction in 28% of the sera. All patients with positive reactions with the crude extract also showed positive weals with the two purified antigens, PAK and PAS. All patients, except three, with a reaction to A. suum antigen, were positive to the EAS antigen. In five patients the weal size produced by PAS was greater than that observed with PAK, whereas in another six patients the contrary was observed. Only one of these six patients did not react to EAS antigen, coincident with the patient showing only a slight increase (7%) in the weal size induced by PAK vs. PAS. When the EAS antigen was tested on patients positive to both PAK and PAS, six patients presented a weal size of >30% and only three patients who were positive to PAS did not react to the EAS antigen. These three patients were also negative against the A. suum CE. Purification by affinity chromatography eliminates from the PAS antigen the proteins responsible for producing cross-reactions with Ascaris (present in the EAS antigen).