Immunotherapy with grass pollen major allergens. Immunological results from a prospective 3-year double blind study

Allergen injection immunotherapy for seasonal allergic rhinitis

BACKGROUND

Allergic rhinitis is the most common of the allergic diseases. Despite improved understanding of the pathophysiology of allergic rhinitis and advances in its pharmacological treatment, its prevalence has increased worldwide. For patients whose symptoms remain uncontrolled despite medical treatment, allergen injection immunotherapy is advised. An allergen-based treatment may reduce symptoms, the need for medication and modify the natural course of this disease.

OBJECTIVES

To evaluate the efficacy and safety of subcutaneous specific allergen immunotherapy, compared with placebo, for reducing symptoms and medication requirements in seasonal allergic rhinitis patients.

SEARCH STRATEGY

We searched the Cochrane Ear, Nose and Throat Disorders Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 1 2006), MEDLINE (1950 to 2006), EMBASE (1974 to 2006), Pre-MEDLINE, KOREAMED, INDMED, LILACS, PAKMEDINET, Scisearch, mRCT and the National Research Register. The date of the last search was February 2006.

SELECTION CRITERIA

All studies identified by the searches were assessed to identify randomised controlled trials involving participants with symptoms of seasonal allergic rhinitis and proven allergen sensitivity, treated with subcutaneous allergen specific immunotherapy or corresponding placebo.

DATA COLLECTION AND ANALYSIS

Two independent authors identified all studies reporting double-blind, placebo controlled randomised trials of specific immunotherapy in patients with seasonal allergic rhinitis due to tree, grass or weed pollens. Two authors independently performed quality assessment of studies. Data from identified studies were abstracted onto a standard extraction sheet and subsequently entered into RevMan 4.2.8. Analysis was performed using the Standardised Mean Difference (SMD) method and a random-effects model; P values < 0.05 were considered statistically significant. The primary outcome measures were symptom scores, medication use, quality of life and adverse events.

MAIN RESULTS

We retrieved 1111 publications of which 51 satisfied our inclusion criteria. In total there were 2871 participants (1645 active, 1226 placebo), each receiving on average 18 injections. Duration of immunotherapy varied from three days to three years. Symptom score data from 15 trials were suitable for meta-analysis and showed an overall reduction in the immunotherapy group (SMD -0.73 (95% CI -0.97 to -0.50, P < 0.00001)). Medication score data from 13 trials showed an overall reduction in the immunotherapy group (SMD of -0.57 (95% CI -0.82 to -0.33, p<0.00001)). Clinical interpretation of the effect size is difficult. Adrenaline was given in 0.13% (19 of 14085 injections) of those on active treatment and in 0.01% (1 of 8278 injections) of the placebo group for treatment of adverse events. There were no fatalities.

AUTHORS' CONCLUSIONS

This review has shown that specific allergen injection immunotherapy in suitably selected patients with seasonal allergic rhinitis results in a significant reduction in symptom scores and medication use. Injection immunotherapy has a known and relatively low risk of severe adverse events. We found no long-term consequences from adverse events.

Does allergen immunotherapy alter the natural course of allergic disorders?

Allergy in patients with atopy is caused by clinical adverse reactions to environmental antigen, which is often associated with allergen-specific immunoglobulin (Ig)E production. Since allergy reflects an inappropriate immunological reaction, a therapeutic approach related to immunology is likely to actively alter the natural course of allergic disorders. Allergen immunotherapy, known at various times as desensitisation or hyposensitisation, is very recently defined by the World Health Organization as therapeutic vaccines for allergic diseases. At present, it has become a common clinical practice in selected patients for the treatment and prevention of the recurrence of allergic disorders caused by insect venoms and has proven to be effective in changing the course of allergic responses induced by grass and tree pollen, animal hair and dander, house dust mite and mold, as demonstrated by improvement in clinical symptoms, skin prick test and medication scores. Reported effects of allergen immunotherapy on the natural course of allergic disorders include (i) prevention of reaction following re-sting in insect venom allergy; (ii) prevention or decrease the rate of the natural progress of allergic rhinitis to asthma; and (iii) inhibition of new sensitisation in monosensitised children. Many aspects of the immune responses associated with allergic disorders, including antibody production, cytokine secretion, T cell activation and local inflammatory reactions, are found to be significantly altered during and/or after immunotherapy. Specifically, the ratio of allergen-specific IgG4 to IgG1 correlates well with positive clinical outcome caused by allergen immunotherapy in patients with pollen-allergy. Allergen immunotherapy affects the cytokine profile of allergen-specific T cells and switches T(H)2 type immune responses in patients with atopy towards T(H)0 or T(H)1 type responses. Although the changes in the absolute value of T(H)1 or T(H)2 cytokines appear quite variable, the increase in the ratio of T(H)1/T(H)2 cytokines is very consistent among published reports, especially in the late stage of treatment. Accumulating evidence indicates that appropriate immunotherapy prevents the onset of new sensitisation and prevents the progress of allergic rhinitis to asthma. Although the changes in B cell and T cell responses, especially IgG antibodies and T(H)1/T(H)2 cytokine production, may be the major mechanism underlying the clinical efficacy of allergen immunotherapy and the prevention of the development of allergic phenotypic changes, multiple mechanisms may be involved in the outcome of alteration of the natural course of allergic disorders.

Immunotherapy with a calcium phosphate-adsorbed five-grass-pollen extract in seasonal rhinoconjunctivitis: a double-blind, placebo-controlled study

BACKGROUND

Calcium phosphate-adsorbed allergen extracts are used for subcutaneous immunotherapy to avoid the use of aluminium adjuvants.

OBJECTIVES

A double-blind, placebo-controlled study was performed in order to confirm the safety and assess the efficacy of a standardized five-grass-pollen extract adsorbed onto calcium phosphate for specific immunotherapy (IT).

METHODS

Twenty-nine patients with seasonal rhinoconjunctivitis were randomized to receive either the active preparation (16 patients) or placebo (13 patients), in a 1-year study. During the increasing dose phase, an extract ranging from 0.1 IR per ml to 50 IR per ml was administered at a rate of one subcutaneous injection per week until a maintenance dose was reached. The patients were assessed by symptom diary and rescue medications during seasonal exposure and specific nasal and skin reactivity before and after IT. Immunological parameters (specific IgE and IgG4 antibodies) were assessed before, during and after IT.

RESULTS

The overall symptoms score (mean AUC) was not significantly different between the IT group and the placebo group during grass-pollen exposure (49.6 vs. 56, respectively). The total medication score (mean AUC) was significantly lower in the IT group than in the placebo group (11 vs. 41, P < 0.01, Mann-Whitney U-test). The cumulative symptom/medication score was significantly lower in the IT group than in the placebo group (64.5 vs. 102.3, P < 0.05, U-test). A significant increase in nasal reactivity threshold was observed after IT in the IT group (21. 4 IR/mL before IT vs. 63.4 IR/mL after IT, P < 0.01, Wilcoxon), whereas no significant changes were observed in the placebo group (31.0 IR/mL before IT vs. 37.7 IR/mL after IT). IT induced a significant reduction in grass pollen cutaneous reactivity in the actively treated group (P < 0.001). A significant increase in serum-specific IgG4 antibody response was observed in the IT group (3.1% before IT vs. 10.1% after IT, P < 0.001). Nine patients in the IT group developed moderate immediate systemic reactions vs. two patients in the placebo group.

CONCLUSION

Specific immunotherapy with calcium phosphate-adsorbed standardized grass pollen extract was safe and effective for the treatment of patients with seasonal allergic rhinoconjunctivitis.

Allergen-specific immunotherapy in birch- and grass-pollen-allergic rhinitis. I. Efficacy estimated by a model reducing the bias of annual differences in pollen counts

BACKGROUND

Evaluation of the efficacy of allergen-specific immunotherapy (IT) with pollen extracts is complicated by annual variation in pollen intensity. Our study aimed to evaluate the efficacy of birch and grass IT, taking into consideration these variations.

METHODS

After 1 year of observation, 52 patients with rhinoconjunctivitis and allergy to birch as well as grass pollen were allocated to double-blinded clustered IT with aluminum-adsorbed extract produced from either birch (Betula verrucosa) pollen or grass (PIleum pratense) pollen. After 1 year of treatment, the patients continued IT with their original extract and also received the other extract. During the three consecutive pollen seasons, the rhinoconjunctivitis symptom score and the use of antihistamines, eye-drops, and oral prednisolone were recorded. Longitudinal data analysis was used to investigate the relation between different pollen counts and the magnitude of clinical efficacy.

RESULTS

An effect of IT was found on symptom score, antihistamine intake, and eye-drop use for both birch and grass (P values <0.05). The mean reduction in symptom score/medication by IT ranged from 24% to 95%, depending on mean seasonal pollen counts. A minimum mean seasonal grass-pollen count of 20-30 pollen grains m3 was required for the efficacy of grass IT to emerge.

CONCLUSIONS

A model was developed for evaluation of efficacy in longitudinal IT studies, taking the differences in annual pollen counts into consideration. The model showed a significant beneficial role of pollen IT in rhinoconjunctivitis patients allergic to birch and grass pollen.

Epidemiology of the M-component immunoglobulin types of multiple myeloma

The purpose of this population-based case-control study was to learn whether risk factors differ for the individual immunoglobulin types of multiple myeloma. In particular, we sought to determine whether IgA and IgG myeloma were related to a history of exposure to reported IgA- and IgG-stimulating conditions, respectively, or to a history of selected occupational and physicochemical exposures. The M-component immunoglobulin type was determined from immunoelectrophoresis as reported in medical records, and exposure status was obtained through in-person interviews. IgG (56 percent) and IgA (22 percent) M-components predominated. For 17 percent of cases, no peak was found on immunoelectrophoresis; they were presumed to have light-chain myeloma. Persons with these three types of myeloma did not differ with respect to distributions of age or race, but a somewhat higher proportion of light-chain cases were women (58 percent cf 45 percent of all other cases). Detailed analysis of the IgA and IgG subtypes provided little evidence that they differ with respect to prior immune stimulation or employment in several specific jobs. IgA myeloma, but not IgG myeloma, was associated modestly with a history of exposure to chest and dental X-rays. Our study provides little evidence that IgA and IgG myeloma differ with respect to the risk factors examined.

Evidence of a common regulation of IgE and IgG-subclass antibodies in humans during immunotherapy

Based on a 3-year prospective study of 20 pollen-allergic patients, where a detailed analysis of the IgE, IgG1 and IgG4 immune response was performed, we propose that a common regulatory mechanism exists between the IgE and IgG1 synthesis and between IgE and IgG4 synthesis during immunotherapy. It was found that the IgE immune response to a number of antigens was quantitatively diminished during the period of immunotherapy when IgG1 was present early (week 12), and for other antigens there was a rise in IgE without an early IgG1 antibody response. Additionally, it was found that for some antigens a rise in IgE antibodies was contrasted by a fall in the IgG4 antibody response and for other antigens the opposite was true, indicating a regulatory mechanism between the IgE and the IgG4 synthesis. A statistical analysis showed that these findings were statistically significant at the 0.01% level for the IgE/IgG1 relationship and at the 0.05% level for the IgE/IgG4 relationship. These findings could have implications for future immunotherapy regimens.

A 10-year prognosis for childhood allergic rhinitis

The prognosis of allergic rhinitis was studied in 154 children aged 3-17 years at diagnosis by means of a detailed questionnaire administered 8-11 years later. The symptoms had completely disappeared in only 15 (10%) patients. The conjunctival symptoms, however, had disappeared or were controlled successfully by topical drug therapy in almost all, and 77 (50%) were managing without medication for allergic rhinitis. Twenty-five (23%) of the 110 children with seasonal allergic rhinitis had a perennial disease at follow-up, in contrast to seven (16%) of 44 with perennial allergic rhinitis originally who had only seasonal symptoms at follow-up. Asthma or wheezing had developed in 29 cases (19%) and was more common (p less than 0.01) among those with perennial allergic rhinitis (15 of 44) than among those with seasonal allergic rhinitis (14 of 110). No significant association was found between age at onset of symptoms, family history of atopic disease or type of treatment for allergic rhinitis and allergic rhinitis still present at follow-up or development of asthma during the observation period.

A computational approach to the description of individual immune responses. IgE and IgG-subclass allergen-specific antibodies formed during immunotherapy

Detailed evaluation of the IgE and IgG-subclass immune response during immunotherapy can now be performed by crossed radio immunoelectrophoresis (CRIE). Some new concepts are introduced facilitating the handling of the vast amount of data obtained by quantitating the immune response. These concepts are "distance" between antibody responses and "immune response width". The 20 patients included in this study were pollen-allergic patients who underwent specific immunotherapy in a 3-year prospective study. It was found that the immune response during immunotherapy was restricted to IgG1 and IgG4 antibodies. The semi-quantitative CRIE analysis correlated with the RAST analysis for the IgE samples before start of immunotherapy, for the IgG1 samples at week 12, and for all the IgG4 samples. During immunotherapy the number of IgG1 antibodies directed to the different antigens increased towards 11 antigens and decreased towards six. For the IgG4 antibodies the number of reactions increased towards 15 antigens and decreased towards four. The increase is generally paralleled by an increase in quantitative immune response as well. For some of the antigens a rise in the IgE antibodies is contrasted by a fall in the IgG4 antibody response, and for other antigens the opposite was true, indicating a regulatory mechanism between the IgE and the IgG4 synthesis. The IgE immune response to a number of antigens, including the major allergens before the start of immunotherapy, was quantitatively diminished during the period of immunotherapy when IgG1 was present early (week 12) in the period, and for other antigens there was a rise in IgE without an early IgG1 antibody response. This suggests that IgG1 can have a regulating influence on the IgE synthesis. Finally, we have found that IgE antibodies with specificities not present in the samples taken before immunotherapy were formed during immunotherapy. These new IgE antibodies do not, however, seem to impair the outcome of treatment.

Hyposensitization in asthmatics with mPEG-modified and unmodified house dust mite extract. III. Effect on mite-specific immunological parameters and correlation to changes in mite-sensitivity and symptoms

Forty-six adult asthmatics allergic to D. pteronyssinus (Dp) participated in a 2-year study. Thirty-one underwent hyposensitization (HS-group). Fifteen were treated with Dp-extract (Dp-group), and 16 with a similar extract modified by monomethoxypolyethylene glycol with reduced allergenicity (mPEG-Dp-group). Fifteen patients served as controls. Dp-specific antibodies and histamine release from blood basophils were determined and compared with Dp-sensitivity in lungs and skin. In addition, IgG and IgE against the major allergen Der p I were followed in a subgroup. Dp-specific IgG, IgG1, and IgG4 increased significantly in both HS-treated groups after 1 and 2 years (median: 2.5- to 11.6-fold). IgG4 was not induced if maintenance dose during the first year was less than 20,000 BU. Median skin sensitivity decreased 4.4- to 8.2-fold after 1 year and 7.4- to 21.4-fold after 2 years. Der p I specific IgG response was unrelated to the occurrence or change in IgE with the same specificity. The mPEG-Dp-extract tended to have less effect on skin sensitivity and immunological parameters, differences reaching statistical significance for skin sensitivity only. In the HS-group, the decrease in bronchial sensitivity was significantly correlated to a decrease in IgE (r = 0.36), IgG1/IgG4 (r = 0.49), Dp-specific histamine release (r = 0.58), and to an increase in Dp-specific IgG4 (r = -0.36) and IgG4/IgE (r = -0.48). In patients improving clinically, Dp-specific IgG4/IgE increased, and median Dp-specific IgE was reduced to 80% compared with an increase to 150-160% seen in the unchanged or deteriorated group (P less than 0.05). Findings indicate an improvement of effect, if the allergen dose is sufficient to reduce specific IgE and/or induce an IgG and especially IgG4 response.

Combination of parenteral and oral immunotherapy in grass pollen-allergic children. A double-blind controlled study of clinical and immunological efficacy

Twenty patients with a proven sensitization to grass pollens were treated with parenteral "priming" and subsequently with either oral "booster" (n = 10) or placebo (n = 10) extension course. The study was carried out in a double-blind manner. Cumulative preseasonal parenteral dosage was 3,100 NU (Noon Units), patients in the oral group subsequently received 123.9 mg of grass pollen extract during the pollen season. No side effects were noted after intake of the oral preparation. No significant difference (95% confidence interval) were noted comparing results of in vivo (skin prick test and conjunctival provocation test) and in vitro tests (specific serum IgE- and IgG-antibodies) between the two groups. Analysis of symptom and medication scores as well as subjective assessment of patients revealed no superiority of oral "booster" over placebo. Data obtained in this study does not support the concept of combined parenteral and oral treatment. This is in contrast to work reported previously.

Double-blind, placebo-controlled immunotherapy with mixed grass-pollen allergoids. II. Comparison between parameters assessing the efficacy of immunotherapy

Specific immunotherapy is effective in alleviating symptoms in grass pollen-induced rhinitis, but there are no clear data demonstrating a correlation between symptom-medication scores and objective parameters. Twenty-five patients taking part in a double-blind, placebo-controlled immunotherapy with mixed grass pollen-formalinized allergoids were studied. All patients had the same investigations. Symptom-medication scores were significantly (p less than 0.005, Mann-Whitney U test) reduced in the treated group by comparison to the placebo-treated patients. Nasal challenges performed with threefold increasing numbers of orchard grass-pollen grains demonstrated that patients treated with allergoid tolerated a significantly (p less than 0.005, Wilcoxon W test) greater number of grains after treatment, whereas there was no mean difference in the placebo-treated patients. There was a significant (p less than 0.005, Spearman rank-correlation) correlation between nasal challenges and symptom scores during the season. The skin prick test end point was significantly (p less than 0.001, Wilcoxon W test) reduced after treatment in the allergoid-treated group and remained unchanged in the placebo-treated group. There was a significant (p less than 0.001) correlation between the skin prick test end point and symptom scores during the season. Serum grass-pollen IgG titrated by a solid-phase radioimmunoassay with Staphylococcus A protein was significantly (p less than 0.01, Wilcoxon W test) increased after treatment with allergoid, but there was no significant correlation between IgG titer and symptom scores during the season. Serum grass-pollen IgE increased (p less than 0.04, Wilcoxon W test) in the treated group but there was no correlation with symptom scores.

The role of immunotherapy in cockroach asthma

To evaluate the preventive role of immunotherapy in severe perennial asthma, we investigated cockroach asthma as a model. Twenty-eight subjects with bronchial asthma due to cockroach hypersensitivity (BACR) were divided into two groups in alternating order: 15 were started with cockroach antigen immunotherapy (CRa-IT) and 13 were given control immunotherapy. Eleven in the former group and two in the latter group completed the study after 5 years. The changes in symptoms and medication scores were assessed; blocking antibody factor in the paired pre- and postimmune serum of the two groups was measured and compared. Cellular sensitivity (HR50) was measured using the basophil-rich leukocytes (BRLs) obtained from the two treated asthma groups, and the result was compared with that of the untreated cockroach asthmatic cells. The average symptom score changed from 7.2 +/- 2.7 to 1.2 +/- 0.4 in the CRa-IT group. The control-IT group showed no change. The medication score changed from 11.4 +/- 1.6 to 5.2 +/- 1.4 in the CRa-IT group only (p less than 0.01). The mean blocking antibody factor in the immune serum of the CRa-IT group showed a 2.5 x 10(2)-fold increase [1.3 +/- 0.3 x 10(-1) in postimmune serum/5.2 +/- 2.0 +/- 10(-4) in preimmune serum (p less than 0.001)]. No difference was noted in the HR50 of the BRLs in the post- and preimmune serum of the control-IT group. Antihuman IgG absorption of the post-CRa-IT serum reduced the blocking antibody to 1/1000-fold; no difference in the HR50 of the BRLs was noted between the post-control-IT and the pre-CRa-IT serum (p greater than 0.2). The BRLs of the CRa-IT asthmatics, however, showed blunted sensitivity not affected by the serum factor (5.8 +/- 1.5 x 10(-2) micrograms/ml in post-CRa-IT serum and 5.6 +/- 1.3 x 10(-2) micrograms/ml in pre-CRa-IT serum) (p greater than 0.2). The BRLs of the control-IT group retained their cell sensitivity as well as the blocking effect of the CRa-immune serum. This study thus demonstrated that CRa-IT reduces symptom and medication scores clinically in cockroach-asthmatic subjects, and the CRa-IT produces the CRa-specific blocking antibody of the IgG type. It also reduces anaphylactic leukocyte sensitivity, which is not affected by humoral factor.

IgG subclass antibody response in grass pollen-allergic patients undergoing specific immunotherapy. Prognostic value of serum IgG subclass antibody levels early in immunotherapy

All four subclasses of IgG antibodies to timothy grass pollen extract were measured by a three-layer immunoradiometric assay in sera from 20 grass pollen-allergic patients who underwent specific immunotherapy in a 3-year prospective study. Both IgG1 and IgG4 antibody levels rose significantly during the first 8 weeks of immunotherapy. IgG1 antibody level passed its peak (median 5.4 U/ml) after 12 weeks. At this time, the ratio between the medians of IgG1 and IgG4 antibodies was 2.25. IgG4 antibody level reached its peak (median 11.6 U/ml) just before termination of immunotherapy. At this time IgG1/IgG4 ratio was 0.43. Two years after the end of immunotherapy, IgG1 and IgG4 antibody levels were 0.0 and 1.8 U/ml in median, respectively. The amounts of IgG2 and IgG3 antibodies detected in the sera were less than 1.6 U/ml and were considered insignificant. Preseasonal serum IgG1 and IgG4 antibody levels did not correlate significantly with symptom scores in the subsequent season. Serum IgG4 level obtained after 12 weeks of immunotherapy was significantly correlated to symptom score in the third season, i.e. the season just after termination of therapy (rs = 0.529, t = 2.567, P = 0.02). In this work, a serum IgG4 antibody level higher than 8.0 U/ml after 12 weeks of therapy predicted poor clinical result at the end of immunotherapy with 100% sensitivity and 87% specificity. An IgG4/IgG1 ratio greater than 1.0 after 12 weeks' therapy had the same predictive value.

Side effects during immunotherapy with purified grass pollen extracts

In a 3-year prospective double blind study, grass pollen allergic patients were allocated to perennial hyposensitization with the timothy major allergens Nos. 19 and 25 (2-component extract) or a 20-component timothy extract. The extracts were biologically standardized and adsorbed to aluminium hydroxide for treatment. Systemic side effects (SSE) had début after 1 1/2-5 h and lasted without treatment 1/2-10 h. Treatment with the 2-component extract showed preponderance of minor SSE (arthralgia, rhinitis, tiredness, headache, conjunctivitis, nausea, flu-like symptoms), but major SSE (urticaria, angioedema, asthma) were equally distributed between treatment with the two timothy extracts. Major SSE complicated the treatment before the first grass pollen season in 33% of the patients vs. only in 3% during the subsequent perennial therapy, and developed (92%) at high single dose of greater than or equal to 1,000 biological units. The majority (69%) were later able to reach the same or higher dose without relapse. Most (62%) patients with major SSE were predicted by high nasal sensitivity before treatment. Only 18% of the patients had immediate local skin reactions of greater than or equal to 2 cm, but delayed local side effects of greater than or equal to 10 cm were recorded in 70%. Immediate skin reactions did not correlate with delayed skin reactions or with SSE, but delayed local side effects tended towards negative correlation with major SSE. A mean area reduction of 50% of the delayed skin reactions was recorded by repetition of a single dose. Subcutaneous nodules appeared at single doses of greater than or equal to 5,000 biological units. Only 5% of the patients contracted nodules during initial preseasonal therapy compared with 38% during subsequent perennial dosage. The nodules contained typical benign granulomas, and the frequency in the two groups was proportionate to the quantity of aluminium in the two extracts.