A study of the human immune response to Lolium perenne (rye) pollen and its components, Lol p I and Lol p II (Rye I and Rye II). II. Longitudinal variation of antibody levels in relation to symptomatology and pollen exposure and correction of seasonally elevated antibody levels to basal values

Can serum white birch (Betula verrucosa) pollen antigen (Bet v 1) immunoglobulin E measurement distinguish between sensitization and allergy?

BACKGROUND

In clinical practice, it is fundamental to distinguish between sensitization and allergy, mainly with respect to polysensitized patients. The aim of this study was to evaluate whether serum immunoglobulin E (IgE) to white birch (Betula verrucosa) pollen antigen (Bet v 1) assessment might be able to differentiate simple sensitization from true allergy.

METHODS

In total, 197 subjects (100 females; mean age 44.9 years) with serum Bet v 1 IgE positivity and history of nasal symptoms were evaluated. Subjects were subdivided in 2 groups: allergic and sensitized.

RESULTS

Allergic patients were 58.4% of the total; they had higher serum Bet v 1 IgE levels than sensitized subjects (p < 0.001). A serum IgE to Bet v 1 value >8.94 kilo units of allergen per liter (kUA/L) was able to differentiate between sensitization and allergy (area under the receiver operating characteristic curve [AUC] = 0.76; diagnostic odds ratio, ie, degree of agreement between health status and dichotomized IgE levels [DOR] = 6.5). Gender and season when the blood was drawn influenced IgE levels.

CONCLUSION

Serum Bet v 1 IgE measurement may be able to differentiate sensitization from allergy in subjects with sensitization to Betulaceae pollen allergens. Thus, Bet v 1 IgE measurement should be considered a useful step in the management of patients with allergic rhinitis due to Betulaceae pollen allergens.

Sensitization to Lolium multiflorum Grass Pollen in Pollinosis Patients: Evaluation of Allergenic Fractions Recognized by Specific IgE Antibodies

BACKGROUND

Lolium multiflorum (Lm) pollen allergens are the major causative agents for rhinoconjunctivitis in Southern Brazil. There have been no studies about the sensitization and allergenic cross-reactivity between Lm and other grass pollens. We evaluated the sensitization of Brazilian pollinosis patients to Lm pollen allergens through skin prick test (SPT) and immunoassays (ELISA and immunoblot).

METHODS

Serum samples from 60 patients with pollinosis and positive SPT to grass pollen extracts (Lm+ group), 30 patients with negative SPT to grass pollen, but positive SPT to mite extracts (Lm- group), and 30 nonatopic subjects (NA group) were tested by SPT, ELISA, and immunoblot using Lm extract. Inhibition immunoassays with Lolium perenne (Lp), mixed grass (Gmix) and Lm extracts were also performed.

RESULTS

A high concordance was found between the Gmix and Lm extracts in SPT. Positivity rates in SPT were also highly concordant with IgE-ELISA results. The assay was able to detect Lm-specific IgE in >95% of Lm+ patients. A significant self- and cross-inhibition was observed in IgE-ELISA, reflecting a high cross-reactivity between the grass pollen allergens. Immunoblot revealed 13 IgE-binding Lm fractions, from which the bands 28-30 kDa and 31-34 kDa were recognized by >90% of Lm+ patients.

CONCLUSION

Lm-specific IgE antibodies are highly cross-reactive with pollen proteins from other grass species. The results indicate that Lm extracts could be used in both SPT and ELISA for a more specific evaluation of IgE responses to Lm grass pollen in Brazilian pollinosis patients.

Combination vaccines for the treatment of grass pollen allergy consisting of genetically engineered hybrid molecules with increased immunogenicity

Most of the 400 million grass pollen-allergic patients worldwide are co-sensitized to several unrelated grass pollen allergens. Based on frequent co-sensitization patterns determined in 200 grass pollen-allergic patients, three recombinant hybrid molecules were developed by polymerase chain reaction-based mending of cDNAs coding for the major timothy grass pollen allergens (Phl p 1, Phl p 2, Phl p 5, Phl p 6) for vaccination against grass pollen allergy. The hybrids rP2-P6, rP6-P2, and rP5-P1 contained most of the epitopes of natural grass pollen extract and induced stronger lymphoproliferative responses in cultured mononuclear cells of grass pollen-allergic patients than did equimolar mixtures of the individual allergens. Immunization of mice with the hybrids yielded higher antibody titers than did immunization with the individual allergen components or grass pollen extract, which suggests that the individual components of the hybrids can serve as molecular scaffolds for each other to enhance their immunogenicity. Antibodies induced with the hybrids in mice inhibited the binding of grass pollen-allergic patients' immunoglobulin E to each of the individual allergens and grass pollen extract and may thus represent protective antibodies. The principle of increasing the immunogenicity of antigens by engineering hybrids thereof may be applied not only for the treatment of polysensitized allergic patients but also for general vaccine development.

Investigation of the tendency to wheeze in pollen sensitive patients

We have undertaken a double blind placebo controlled study of the effect of nasal beclomethasone on the tendency to wheeze in 20 unselected hay fever sufferers, half with a history of previous seasonal wheezing. We found no difference between either bronchial hyperresponsiveness, as measured by methacholine challenge, home-monitored PEFR, nor recorded wheeze nor cough between treated and placebo groups although the numbers were small. All were allowed the antihistamine cetirizine hydrochloride 10 mg daily. Eighteen out of the 19 patients had either bronchial hyperresponsiveness (PD20 methacholine < 8 mumol or a > 2 doubling dose change in their PD20 during the pollen season). We have shown a significant positive correlation between a hay fever score (HFS) (created by taking the sum of the home scored; nasal discharge, nasal blockage, eye irritation, sneeze and antihistamine use) and peak seasonal specific IgE to mixed grass pollen (Spearman correlation coefficient 0.5 P < 0.02). There was also a positive correlation between the rise in specific IgE from pre to peak season and the HFS, correlation coefficient 0.6 P = 0.03).

Serum levels of IgE-binding factor (soluble CD23) in diseases associated with elevated IgE

Several in-vitro experiments suggest that the low affinity receptor for IgE (Fc epsilon RII) and its soluble fragment (IgE-binding factor, IgE-BF) are multi-functional molecules and more particularly that they are capable of regulating the synthesis of human IgE. In an attempt to examine the in-vivo significance of these in-vitro observations, the serum level of IgE-BF was measured in individuals with allergic or parasitic diseases, both associated with an increased production of IgE. IgE-BF was measured by a radioimmunoassay employing two mAbs against Fc epsilon RII (mAbER). We first compared 257 allergic subjects to 172 non-allergic controls matched for age and sex. Statistical analysis of the data, after logarithmic transformation of IgE-BF and IgE values, revealed that despite a great overlap, the allergic subjects had significantly higher levels of IgE-BF. The correlation between IgE and IgE-BF was very weak but significant. Allergic or non-allergic children had significantly higher IgE-BF levels than the corresponding groups of adults; moreover, the inverse correlation between age and IgE-BF levels was significant only in the children and not in the adults. The IgE-BF levels were not influenced by gender, by hyposensitization therapy or by treatment with local steroids. Subjects receiving systemic steroids had lower IgE-BF levels than untreated subjects.(ABSTRACT TRUNCATED AT 250 WORDS)