Affinity Of IgE Antibodies Research Articles

T-Cell Activation Mediated by Facilitated Antigen Presentation (FAP) Is Directly Affected by Individual IgE Antibody Affinity

T-Cell Activation Mediated by Facilitated Antigen Presentation (FAP) Is Directly Affected by Individual IgE Antibody Affinity

Calculation of the affinity constant KASS for solid phase antigen : A model system using monoclonal antibodies against the cat allergen Fel d I

In this report a procedure is described to calculate the affinity constant of an antibody for solid-phase Ag. K SP ( K ASS solid phase) was defined as the reciprocal of the concentration of Ag required for half saturation of the Ab-binding sites, extrapolated to an infinitely small concentration of Ab (semi-saturation plot). Using this procedure, the affinity of IgE antibodies can be measured without interference from ‘invisible’ IgG antibodies. As a model system, mAbs against the cat allergen Fel d I were used. Serial dilutions of Fel d I-Sepharose were incubated with serial dilutions of mAb Fd1a and Fd1b, with or without rabbit antibodies as ‘invisible’ antibodies. The Ab-binding capacity of Sepharose-coupled Fel d I was low: 4.15% and 2.13% of the expected value for mAb Fd1a and Fd1b, respectively, and this must be taken into account when calculating K SP. The K values of mAb Fd1a and Fd1b, calculated from the y axis intercept of the semi-saturation plot, were 85 (pmol/test) −1 and 65 (pmol/test) −1 respectively. Using the semi-saturation plot, K SP of mAb Fd1a was not affected by the presence of rabbit antibodies against Fel d I, confirming the applicability of the procedure for measuring the K SP of IgE in patient sera. For one cat-allergic patient the K SP of IgE and IgG4 for Fel d I were calculated and found to be 62 (pmol/test) −1 and 147 (pmol/test) −1 for IgE and IgG4 respectively.

Serial studies on the functional affinity and heterogeneity of antibodies of different IgG subclasses to phospholipase A 2 produced in response to bee-venom immunotherapy

High functional affinity and high titer IgG4 antibodies to phospholipase A 2 were produced by allergic patients in response to bee-venom immunotherapy. In contrast, the affinity of IgG1 antibodies decreased after immunotherapy, and both the titer and affinity of IgG1 antiphospholipase A 2 remained significantly lower compared to IgG4 1 to 2 years after treatment. Analysis of affinity heterogeneity suggested a loss of IgG1 high-affinity antibody-producing clones during immunotherapy and a preferential expansion of IgG4 clones. High-affinity IgE antibodies were found in untreated allergic patients, and preliminary results suggest that immunotherapy may result in an early marked decrease in the affinity of IgE antibodies.