Grass pollen hyposensitization versus placebo therapy. II. Immunotherapy-induced changes in serum IgE and IgG levels.

Abstract

This study presents the pre‐ and post‐treatment levels of specific IgE and IgG and of total IgE in the sera of two groups of grass pollen‐sensitive patients, one receiving placebo injection (16 patients), the other being treated by repeated doses of a four‐grass pollen extract (17 patients).Total and specific IgE were evaluated by the radioimmunological methods based on the IgE‐anti‐IgE interaction. IgG specific to the pollen extract was determined by a radioimmunoassay measuring protein‐A bound pollen‐specific antibodies (IgG). The whole immunoglobulin content specific to the allergen was quantified by a haemagglutination technique.During the treatment period, the relative variations of total IgE, and specific IgE and IgG levels are significantly different in placebo‐ and pollen‐treated groups: 1) for total and specific IgE, were observed a relative decrease in the placebo group, and stable levels in the treated group; 2) for IgG, the level was stable in the placebo group and a relative increase was seen in the treated group.For most of the patients the specific serum IgE and IgG levels were determined also after the pollen season consecutive to the treatment. During the pollen season, the placebo group is characterized by an increase in specific IgE concentrations and stable IgG levels. The hyposensitized patients showed stable levels of specific IgE and a decrease in specific IgG during the same period.There is a significant correlation between the levels of specific haemagglutination litres and the IgG levels. After the treatment period the haemagglutination litre is significantly lower in the placebo‐treated patients than in the pollen‐treated ones.A significant positive correlation exists between the levels of specific IgE and IgG before and after treaiment, for the 33 patients. Moreover, during hyposensitization, the relative variations of specific IgE and IgG are highly correlated in the treated group only.No significant correlation at the P < 0.05 level is observed between the clinical scores and the levels of the different biological parameters.