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.


OBJECTIVE
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.


CONCLUSIONS
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.
Michils
A
A
Chest Department, CUB Erasme, Brussels, Belgium.
Mairesse
M
M
Ledent
C
C
Gossart
B
B
Baldassarre
S
S
Duchateau
J
J
D000328:Adult; D000906:Antibodies / Q000276:immunology*; D000918:Antibody Specificity; D000941:Antigens / Q000276:immunology*; D001514:Bee Venoms / Q000276:immunology*; D001710:Biotin; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology*; D007074:Immunoglobulin G / Q000145:classification / Q000276:immunology; D007700:Kinetics; D008297:Male; D010741:Phospholipases A / Q000276:immunology*; D054467:Phospholipases A2
D000906:Antibodies; D000941:Antigens; D001514:Bee Venoms; D007074:Immunoglobulin G; D001710:Biotin; D010741:Phospholipases A; D054467:Phospholipases A2