ISOTYPIC ANALYSIS OF GRASS-POLLEN-SPECIFIC ANTIBODIES IN HUMAN PLASMA.3. RELATIONSHIP TO AUTOANTIBODIES TO IGE

Since it has been shown that autoanti-IgE may be mistaken for antialle rgen antibodies, thus appearing as pseudo-allergen-specific antibodies , it is crucial to separate true- from pseudo-allergen-specific antibo dies and to determine to what extent autoanti-IgE appeared as pseudo-a llergen-specific antibodies. For this purpose, human Ig pools were aff inity-purified successively on a grass-pollen column and then on an an tihuman-IgE column. IgG1-4, IgA, and IgM antibodies that were eluted f rom the grass-pollen column separated into pseudo- (similar to 30-40%) and true-allergen-specific antibodies that were coretained and not co retained, respectively, with the IgE on the anti-IgE column. Levels of autoanti-IgE were determined in individual plasma samples by surface plasmon resonance and statistically compared to the concentrations of allergen-specific antibodies obtained previously in the same plasma sa mples. A positive correlation between IgM autoanti-IgE levels and gras s-pollen-''specific'' IgM concentrations (P < 0.0002), and negative co rrelations between IgA autoanti-IgE and both IgE anti-grass pollen and IgG2 autoanti-IgE levels (P < 0.03, in both cases) were observed for the first time. This supports the contentions that: (1) autoanti-IgE a ntibodies appeared as pseudo-grass-pollen-specific antibodies, (2) the y hid IgE antibodies when the latter were measured, and (3) they compe te with one another in binding IgE. Lastly, a model of large Ig comple xes is discussed.