IgG subclass antibody markers in grass pollen immunotherapy.

Rye grass immunotherapy was clinically effective in seasonal allergic asthma and induced serologic changes different from those of natural exposure. These included the blunting of the seasonal rise in IgE antibody and much greater increases in blocking IgG antibodies. Blocking antibody responses to rye grass antigens were restricted to the IgG1 and IgG4 subclasses. Nonatopic individuals had similar preseasonal levels of IgG1 antibodies, but low or undetectable levels of IgG4 or IgE, compared to allergic subjects. Immunotherapy induced increases in both IgG1 and IgG4 antibodies, but IgG4 was dominant and the rise was much more dramatic. Rye grass extract contained at least eight IgE binding allergens and 11 IgG binding antigens, by far the most important of which was antigen I. IgE and IgG binding antigens generally showed concurrence in individuals, but heterogeneity between individuals for non-Rye 1 antigens. Finally, while IgG4 quantitatively dominated the blocking response, early clinical benefits might involve IgG1 antibodies, suggested by an observed inverse correlation between individual symptom medication scores individuals and IgG1 antibody levels.