Allergen induced cytokine profiles in type I allergic individuals before and after immunotherapy

Conformational IgE Epitope Mapping of Der p 2 and the Evaluations of Two Candidate Hypoallergens for Immunotherapy

Epitope mapping of Der p 2, a clinically important dust-mite allergen is the first step in designing immunotherapy hypoallergen vaccine candidates. Twenty-one single alanine mutants of Der p 2 were generated and their secondary structure was analysed using circular dichroism spectra. Only one mutant, K96A resulted in a misfolded protein. All mutants were tested for serum IgE reactivity using serum from dust mite allergic individuals by immuno dot-blots. Mutations to five residues, N10, E25, K77, K96 and E102 consistently showed reduced IgE reactions compared to wild-type Der p 2, and therefore these residues constitute the major IgE epitopes of Der p 2. Two mutants with consistent low IgE binding, K96A and E102A, were subsequently evaluated as hypoallergen candidates. IgG antibodies raised in mice against both mutants could inhibit human IgE-binding to WT Der p 2. Both mutants had intact T-cell epitopes as they were able to stimulate peripheral blood mononuclear cell proliferation similar to WT Der p 2. However, a switch in Th1:Th2 cytokine profile was not observed. In summary, we have identified the major conformational epitopes of Der p 2, and evaluated two Der p 2 hypoallergen vaccine candidates for immunotherapy.

Modulation of in vivo and in vitro cytokine production over the course of pregnancy in allergic and non-allergic mothers

Cytokines secreted during pregnancy may influence immune development of the foetus. This study aimed to determine if maternal allergy alters patterns of systemic cytokine production throughout and after pregnancy. Maternal plasma cytokines and allergen-specific production of interleukin (IL)-10, IL-13 and interferon (IFN)-gamma were measured in allergic (n = 63) and non-allergic (n = 70) pregnant women who had a full set of sequential peripheral blood samples collected at 20-, 30-, 36-wk gestation and 6-wk post-partum. Maternal allergy was strictly defined by both allergen sensitization and doctor-diagnosed asthma, eczema or rhinitis. IL-13 responses to allergen were higher for allergic mothers at all time-points (20 wk: p < 0.001; 30 wk: p = 0.001; 36 wk: p < 0.001; post-partum: p < 0.001). For the non-allergic group, IL-13 levels to house dust mite decreased from 20- to 36-wk gestation (Friedman ANOVA p = 0.012) and were significantly lower at 36 wk compared with post-partum (p = 0.002). In contrast, IL-13 production by allergic mothers did not change from 20 wk through to post-partum. For both allergic and non-allergic mothers, in vitro IFN-gamma production was lower at all pregnancy time-points compared with post-partum levels. Allergic women had an increased propensity for peripheral blood allergen-specific T helper-2 responses during pregnancy, and failed to downregulate these responses in comparison with non-allergic women. This may be a factor that contributes to the increased risk of atopy in infants born to allergic mothers.

Immunotherapy with mosquito (Culex quinquefasciatus) extract: a double-blind, placebo-controlled study

BACKGROUND

Mosquito allergy is well established, but mosquito immunotherapy requires validation using clinical and immunologic variables.

OBJECTIVE

To evaluate the tolerability and efficacy of specific immunotherapy with Culex quinquefasciatus (mosquito) extract.

METHODS

We performed a randomized, double-blind, placebo-controlled trial of immunotherapy for 1 year in 40 patients with asthma, rhinitis, or both. Patients were evaluated by means of intradermal testing, symptom and drug scores, and histamine provocation testing before and after 1 year of immunotherapy. Mosquito specific IgE and IgG subclass antibody responses were evaluated at the basal level and after 1 year.

RESULTS

Patients receiving allergen immunotherapy for 1 year showed a significant improvement compared with baseline and patients receiving placebo regarding skin reactions, symptom scores (rhinitis and asthma), and forced expiratory volume in 1 second. Provocation concentration of histamine that caused a decrease in forced expiratory volume in 1 second of 20% by inhalation was elevated in the group receiving immunotherapy. In the active group serologic analysis showed a slight reduction in IgE levels (P = .02) but a significant elevation in IgG4 levels (P = .001), with a significant decrease in the IgE/IgG4 ratio (P = .001). All these changes in the placebo group were nonsignificant.

CONCLUSIONS

Allergen immunotherapy with mosquito extract was well tolerated, with improvement in symptoms and airway reactivity. Good clinical outcome was associated with increased IgG4 antibody levels.

Potential role of interleukin-10-secreting regulatory T cells in allergy and asthma

Allergic diseases are caused by aberrant T-helper-2 immune responses in susceptible individuals. Both naturally occurring CD4(+)CD25(+) regulatory T cells and inducible populations of antigen-specific interleukin-10-secreting regulatory T cells inhibit these inappropriate immune responses in experimental models. This article discusses the evidence that regulatory T-cell function might be impaired in allergic and asthmatic disease and that certain therapeutic regimens might function, at least in part, to promote regulatory T-cell generation. Current research strategies seek to exploit these observations to improve the generation of allergen-specific regulatory T-cell populations with the potential to provide the safe and long-term alleviation of disease symptoms.

The effect of Japanese cedar-specific immunotherapy on cytokine production in peripheral blood mononuclear cells

The most common cause of seasonal allergic rhinitis in Japan is the Japanese cedar (JC). Recently, a pullulan-conjugated antigen (CS-560) has been developed to reduce adverse effects and to enhance the effect of JC-specific immunotherapy (IT). If the mechanism of IT can be fully elucidated and the treatment can be used safely and with specificity, IT should be reconsidered as a superior treatment for JC pollinosis. Thirteen patients with JC pollinosis who received IT were compared to 10 patients who did not receive IT. All patients were followed through two pollen seasons by means of allergy diaries. Peripheral blood mononuclear cells (PBMC) were collected before IT and just before each pollen season, and these were stimulated with pollen extract. The concentrations of IL-4, IL-5, IL-13 and IFN-gamma in the culture supernatants were determined using an ELISA. Furthermore, messenger (m)RNA expressions of IL-4 and IL-5 from cultured PBMC were also studied. As a result of the allergy diaries, we confirmed the clinical efficacy of CS-560. The symptom-medication scores were significantly decreased by IT. The levels of IL-4, IL-5 and IL-13 declined only in the IT group. However, the level of IFN-gamma did not change in either group. IL-4 and IL-5 mRNA expressions were inhibited in the IT group compared to that in the non-IT group. In conclusion, specific IT for JC pollinosis using CS-560 clearly modified cytokine expression by PBMC.

Cytokine production by peripheral blood mononuclear cells following birch-pollen immunotherapy

We studied the Th2/Th1 balance by short-term stimulation of peripheral blood mononuclear cells (PBMC) isolated during the pollen season from seven allergic patients treated with conventional birch-pollen immunotherapy (IT) for 18 months, eight matched allergic control patients and 10 non-atopic individuals. The PBMC were cultured for 7 days with birch-pollen extract (BPE) or tetanus toxoid (TT), and then restimulated with PHA and PMA to induce high IL-5, IL-10 and IFN-gamma production. The serum levels of birch-pollen-specific IgG and IgG4 were significantly elevated after IT treatment. The proliferative response to BPE was significantly enhanced in the allergic control group, but not in the IT-treated group, compared to the non-atopic group (P<0.05). Birch-pollen-specific IL-5 production was significantly enhanced in both the IT-treated group and the allergic control group (P<0.01-0. 05). Furthermore, both the IT-treated group and the allergic control group had a cytokine profile to BPE significantly more Th2 polarized (high IL-5/IFN-gamma ratio) than to TT (P<0.05 and P<0.01, respectively). No differences in IL-10 production between the three study groups were observed. The Th2/Th1 balance in vitro correlated with the serum concentrations of birch-pollen-specific IgE (r=0.60, P<0.05), and in the IT-treated group, also with the IgG and IgG4 levels (r=0.79, P<0.05 and r=0.86, P<0.05, respectively). We conclude that conventional birch-pollen IT does not lead to changes in the cytokine profile of the circulating pool of allergen-specific T cells during birch-pollen season. However, induction of peripheral T-cell tolerance and increased production of specific IgG and IgG4 might be part of the mechanisms of IT.

Allergen induced mRNA expression of interleukin-5, but not of interleukin-4 and interferon-gamma, in peripheral blood mononuclear cells obtained before the pollen season predicts the clinical efficacy of immunotherapy for seasonal allergic rhinitis

The primary aim of this study was to investigate whether the allergen-induced synthesis of cytokines by peripheral blood mononuclear cells (PBMCs) obtained immediately before the pollen season could predict the clinical efficacy of immunotherapy during the following pollen season. PBMCs (1.0 x 106 cells/ml) were obtained from 17 nonatopic subjects and from 60 patients receiving immunotherapy for seasonal allergic rhinitis (caused by Japanese cedar pollens) immediately before the pollen season of 1998, and were cultured for 24 h in the presence of 10 mg/ml of Cry j 1, a major allergen of Japanese cedar pollens, at 37 degrees C in a fully humidified 5% CO2 atmosphere. Total cellular RNA was extracted from the PBMCs, and the allergen-induced interleukin (IL)-4, IL-5 and interferon-gamma (IFN-gamma) mRNA expression was determined using a reverse transcription-polymerase chain reaction. According to the nasal symptoms during the pollen season of 1998, the 60 patients on immunotherapy were divided into 36 good responders (who had no nasal symptoms and no requirement for rescue medications) and 24 poor responders who needed rescue medications to control nasal symptoms. Neither IL-4 mRNA nor IL-5 mRNA was expressed in any of the 17 nonatopic individuals. By contrast, IL-4 mRNA was expressed in 26 good responders and in 22 poor responders, and IL-5 mRNA was expressed in eight good responders (22.2%) and in 23 poor responders (95.8%). IFN-gamma mRNA was expressed in four nonatopic subjects, in nine good responders and in seven poor responders. The expression of IFN-gamma did not differ significantly among the nonatopic subjects, the good responders and the poor responders. The mRNA expression of IL-5 (P < 0.0001), but not of IL-4 (P = 0.0999) and IFN-gamma (P = 0. 7713), differed significantly between the good and poor responders. Therefore, our study has highlighted that positive expression of IL-5 mRNA in PBMCs sampled immediately before the pollen season could be predictive of a poor clinical outcome of immunotherapy during the following pollen season and that the down-regulation of IL-5 mRNA expression in PBMCs could be an important mechanism of pollen immunotherapy related to the clinical efficacy.

The kinetics of change in cytokine production by CD4 T cells during conventional allergen immunotherapy

BACKGROUND

The effect of conventional allergen immunotherapy on allergen-specific T lymphocyte cytokine production is incompletely understood, particularly during the initial phase of treatment.

OBJECTIVE

The purpose of this study was to prospectively follow the kinetics of change in CD4(+) T cell cytokine secretion during the course of conventional immunotherapy.

METHODS

Six allergic individuals were treated with extracts of Dermatophagoides farinae/Dermatophagoides pteronyssinus or with rye grass pollen (Lolium perenne) allergen, but not both, by using an internally controlled conventional immunotherapy protocol. CD4(+) T cells from peripheral blood were examined in vitro at varying intervals after the initiation of immunotherapy by stimulation with D farinae or L perenne group I antigen. The quantity of IL-4 and IFN-gamma produced and its relationship to clinical improvement was determined.

RESULTS

The ratio of allergen-specific IL-4/IFN-gamma production by CD4(+) T cells from 4 of 6 individuals receiving immunotherapy greatly increased during the period when the dose of allergen was increasing. However, after high-dose maintenance therapy was achieved, this ratio decreased in subjects responding clinically to, but not in those failing, immunotherapy. In addition, late-phase skin reactions and allergen-specific IgE levels in responding, but not in nonresponding, subjects diminished over the course of immunotherapy.

CONCLUSION

Conventional immunotherapy may initially exacerbate allergic disease by increasing allergen-specific IL-4 and allergen-specific IgE production. Later clinical improvement is associated with a reduction in allergen-specific IL-4 production and in allergen-specific serum IgE.