Béatrice Gossart

Modified antigenic reactivity of anti-phospholipase A2 IgG antibodies in patients allergic to bee venom : Conversion with immunotherapy and relation to subclass expression

BACKGROUND We have previously reported that, in addition to modifying IgG levels and subclass distributions, wasp venom immunotherapy (VIT) rapidly changes IgG antibody specificity. OBJECTIVES We investigated whether such a change can be documented in the IgG response to the major bee venom allergen, phospholipase A2 (PLA2), from patients allergic to bees treated with VIT; whether it is coupled to the shift in IgG subclass distribution (IgG4 predominance) usually observed during VIT; and whether it restores the specificity displayed by IgG antibodies from nonallergic individuals. METHODS Antibody specificity was evaluated in 17 patients allergic to bee venom in competitive ELISAs by using streptavidin biotin technology. Patients were tested before and during specific immunotherapy (at 15 days and 6 months) and compared with another group of 17 patients treated with venom injections for at least 2 years (VIT patients) and 30 healthy individuals. RESULTS The capacity of individual sera to prevent PLA2 binding of pooled IgG from allergic patients changed rapidly with mean percentage inhibitions falling from 84% +/- 14% before starting VIT to 27% +/- 13% and 28% +/- 7% after 15 days and 6 months of treatment, respectively (p < 0.001 by one-way analysis of variance [ANOVA]). IgG titers were only slightly increased. The capacity of individual sera to prevent the binding of pooled IgG from patients receiving VIT changed rapidly with mean percentage inhibition increasing from 60% +/- 12% before starting VIT to 85% +/- 6% and 82% +/- 6% after 15 days and 6 months of treatment, respectively (p < 0.001 by one-way ANOVA). Similar results were found regardless of whether pooled IgG1 or pooled IgG4 were used. CONCLUSION VIT results in a rapid change in the antigenic reactivity of anti-PLA2 IgG antibody of human allergic sera, restoring, although not completely, the specificity peculiar to lgG from healthy individuals. This suggests that allergic status and immunoprotection correlate with the preferential expression of distinct IgG specificities, which appear equally distributed over the IgG1 and IgG4 antibody subclasses. It is, however, not known whether the shift in IgG specificity is one of the operative mechanisms of VIT.

Wasp venom immunotherapy changes IgG antibody specificity.

Background The evolution of the IgG response during venom immunotherapy (VIT) has been previously investigated in terms of antibody titres and subclasses.

Lung cancer-related changing profile of B-cell epitopes recognized on mucosal antigens : the Der p1 model

Background. The natural immunoglobulin G (IgG) response towards antigens presented at the mucosal level in patients with lung cancer, the most frequent mucosal malignancy in humans was studied. Compared with healthy control subjects, patients with lung cancer display lower IgG antibody titers toward antigen p1 of the house dust mite, Dermatophagoides pteronyssinus (Der p1), chronically presented to the respiratory mucosa. The present study further characterizes this defect in terms of antibody specificity.

Antibody affinity disturbance in the immunoglobulin immune response to mucosal antigenic stimulation in lung cancer: The betalactoglobulin model

Background. This study is a continuation of a recent study, in which a defect in the immunoglobulin G (IgG) response to some natural antigens (bovine betalactoglobulin [BLG] from cows milk and antigen p1 from the house dust mite Dermatophagoïdes pteronyssinus), usually presented at the mucosal level, was documented in lung cancer patients. The present study further characterizes this difference in terms of antibody relative functional affinity in the BLG model.

A different profile of epitopic dominance in the immunoglobulin G response to bovine betalactoglobulin in lung cancer

Background. The authors previously documented a quantitative defect in the immunoglobulin G (IgG) response toward bovine betalactoglobulin (BLG), the major cows milk antigen, and antigen p1 of the house dust mite, Dermatophagoides pteronyssinus (Der p1), in patients with lung cancer. In the Der p1 model, the authors documented at the IgG level an epitope specificity that differed between patients with lung cancer (preferential specificity for cryptic epitopes) and healthy control subjects and patients with mite allergy. The current study investigated whether this varying specificity might be extended to the IgG response toward BLG.