Immunotherapy in Europe

One hundred years of allergen immunotherapy European Academy of Allergy and Clinical Immunology celebration: review of unanswered questions

Allergen immunotherapy was introduced by Leonard Noon 100 years ago and is the only disease-modifying treatment for allergic individuals. Improved understanding of immunology has taught us a great deal about the underlying mechanisms involved in allergen immunotherapy; however, despite these developments, a number of important questions remain unanswered. Several of these questions relate to the practice of allergen immunotherapy in the clinic, such as: Is it possible to unify units of allergen potency? Which treatment schedules are best? Is allergen immunotherapy effective in all patient groups? Is there a dose-response relationship for efficacy and safety?, and Is there evidence for long-term effects following allergen immunotherapy? Others are related to new developments, such as new indications, or developments in the production of allergens. On the centenary of Noon's discovery, European experts in the field of immunotherapy met in Geneva under the aegis of the EAACI to discuss these controversial issues. This study presents outcomes and conclusions from these discussions.

Long-term allergen-specific immunotherapy correlates with long-term allergen-specific immunological tolerance

INTRODUCTION

One method of treatment for allergic diseases is allergen-specific immunotherapy (SIT). The clinical efficacy of SIT in pollen-induced allergic rhinitis has been demonstrated in several controlled clinical trials. There is no consensus about the protective effect of SIT. In this study, we evaluated the correlation between the duration of SIT and relapse of allergic rhinoconjunctivitis.

METHODS

We evaluated 148 patients who had received SIT between 1998 and 2006. All of the patients had allergic rhinoconjunctivitis. According to the data 116 had sensitivity to grass pollen and 32 to house dust. SIT was performed on 87 patients for 4 y (Group A) and 61 patients for 6 y (Group B).

RESULTS

All of the 148 patients were monitored regularly with no medication for 2 y after SIT. Thirty-one patients in Group A relapsed (36%); 11 patients in Group B relapsed (18%). Mean duration until relapse was 11.1+/-1.99 mo in Group A and 19.64+/-1.86 mo in Group B. During evaluation, symptom scores were 2.32+/-0.74 in Group A and 1.81+/-0.75 in Group B and serum total immunoglobulin E levels were 432.4+/-78.5 KU/lt in Group A and 288.6+/-55.3 KU/lt in Group B. There was significant difference between the groups (P < 0.05).

CONCLUSION

According to these results, long-term SIT therapy correlates with long-term, allergen-specific, acquired immunological tolerance.

BSACI guidelines for the management of allergic and non-allergic rhinitis

This guidance for the management of patients with allergic and non-allergic rhinitis has been prepared by the Standards of Care Committee (SOCC) of the British Society for Allergy and Clinical Immunology (BSACI). The guideline is based on evidence as well as on expert opinion and is for use by both adult physicians and paediatricians practicing in allergy. The recommendations are evidence graded. During the development of these guidelines, all BSACI members were included in the consultation process using a web-based system. Their comments and suggestions were carefully considered by the SOCC. Where evidence was lacking, consensus was reached by the experts on the committee. Included in this guideline are clinical classification of rhinitis, aetiology, diagnosis, investigations and management including subcutaneous and sublingual immunotherapy. There are also special sections for children, co-morbid associations and pregnancy. Finally, we have made recommendations for potential areas of future research.

[Respiratory allergy and good clinical practice]

The increase of allergic diseases and asthma requires a rationalization of diagnostic and therapeutic methods. Medical society guidelines and position papers attempt an approach to harmonization for good clinical practice in the field of allergy worldwide, especially immunotherapy.

Comparison of the efficacy of subcutaneous and sublingual immunotherapy in mite-sensitive patients with rhinitis and asthma--a placebo controlled study

BACKGROUND

The efficacy of therapy with sublingual allergen extracts is unproven.

OBJECTIVE

To evaluate the clinical and immunologic outcome of sublingual immunotherapy and to compare the results with subcutaneous immunotherapy and placebo in 36 patients with rhinitis and asthma due to mite allergy.

METHOD

Thirty-six patients with rhinitis and asthma due to mite allergy were randomly divided into three groups in order to receive subcutaneous injections with allergenic extracts, sublingual drops with solutions of purified standardized allergen preparations, or sublingual placebo for a period of 1 year. Assessment of clinical and immunologic efficacy included symptom and medication scores, methacholine provocation tests, skin prick tests, and specific IgE and IgG4 antibody concentrations.

RESULTS

Subcutaneous immunotherapy for both rhinitis and asthma was clinically effective. Patients treated with sublingual immunotherapy had decreased rhinitis symptoms (P < .01) but no change in asthma scores. Medication scores significantly decreased in both actively treated groups (P < .01) at the first year compared with baseline. When skin prick tests were evaluated, the subcutaneously treated group had a significant decrease in the wheal diameter of D. pteronyssinus (P < .01), D. farinae (P < .05), and histamine (P < .05) while other two groups showed no difference. There was no significant change in methacholine PC20 values in all groups at the end of the first year when compared with baseline. No change in D. pteronyssinus and D. farinae specific IgE levels were observed; however, specific IgG4 concentrations were significantly higher than baseline both in sublingual and subcutaneous immunotherapy groups (P < .05) after 1 year immunotherapy. No significant difference was obtained in any of these parameters in the placebo group.

CONCLUSION

Sublingual immunotherapy may be effective in patients with allergic rhinitis. Further, we believe it is a potential therapy for allergic asthmatic patients. The clinical usefulness of this form of immunotherapy (when administered to larger study groups for a longer time) and the mechanisms underlying its immunologic effect deserve additional studies.

Natural course of serum-specific immunoglobulin E and immunoglobulin G4 for a span of eight years in untreated patients with perennial allergic rhinitis

During the past two decades, considerable attention has been devoted to the clinical role of serum-specific IgE and IgG4 following immunotherapy. To definitely discuss the clinical role of serum-specific IgG4, we should know the natural course of serum-specific IgG4 in the untreated patient with allergic rhinitis. To our knowledge, however, no such kind of study can be found in the literature. Our present study focused on the long-term follow-up of serum-specific IgE and IgG4 in patients who were not treated with immunotherapy for perennial allergic rhinitis. They were scheduled to take no medication for their perennial nasal symptoms for 8 years. Serum-specific IgE and IgG4 in untreated patients with perennial allergic rhinitis never significantly change during the observation period. These data will be of great value for studies in serologic changes following active treatment for atopic diseases. Additionally, our study suggests that a reduction in serum-specific IgE and an increase in serum-specific IgG4 following immunotherapy are not the result of an immunotherapy-independent and age-related phenomenon but the result of active immunologic modulation by immunotherapy.

Serum levels of soluble interleukin-2 receptor in patients with perennial allergic rhinitis before and after immunotherapy

BACKGROUND

Interleukin-2 receptor (IL-2R) exists in soluble form in sera, and the rate of release of the soluble form of IL-2R (soluble IL-2R) reflects T cell activation in vivo. Since T lymphocytes play a central role in respiratory allergic disorders, the measurement of serum levels of soluble IL-2R may be useful in analyzing the disease state of allergic disorders.

OBJECTIVE

To investigate the serum concentrations of soluble IL-2R in 48 patients with perennial allergic rhinitis and 14 nonatopic healthy controls, with special reference to the possible changes following long-term immunotherapy.

METHODS

This retrospective study included 48 patients who had had variable periods of long-term immunotherapy with Dermatophagoides farinae extracts. The duration of immunotherapy ranged from 5 to 15 years. Serum samples were collected twice from each patient, before the initiation of immunotherapy and at the time of clinical assessment of immunotherapy. All the serum samples were simultaneously used for determination of soluble IL-2R concentrations, by the use of an enzyme-linked immunosorbent assay. To serve as controls, 14 nonallergic subjects of the same age range and sex were chosen.

RESULTS

Patients with allergic rhinitis before immunotherapy had significantly higher serum levels of soluble IL-2R than nonatopic subjects. Elevated serum levels of soluble IL-2R decreased significantly following immunotherapy and the serum levels of soluble IL-2R in patients with allergic rhinitis after immunotherapy were not statistically different from those of nonatopic subjects. In addition, the percent decrease in serum soluble IL-2R correlated significantly with the duration of immunotherapy.

CONCLUSIONS

Hyperactivity of helper T cells of atopic patients is altered after long-term immunotherapy, and such immunoregulatory changes could be theoretically involved in the mechanisms of immunotherapy.

Immunotherapy for childhood asthma: is there a rationale for its use?

OBJECTIVE

This paper reviews the literature regarding immunotherapy in the management of childhood asthma. Immunotherapy is a well established treatment of venom allergy and allergic rhinitis, however its use in asthma remains controversial.

DATA SOURCES

We reviewed the pediatric literature from 1966 to 1994 and evaluated the existing studies for clinical efficacy of immunotherapy in childhood asthma.

STUDY SELECTION

Only 12 purely pediatric studies existed over the time period that we reviewed. The studies used a variety of different antigens including house dust, house dust mite, grass, mold, cat, dog, and combinations of antigens.

RESULTS

In reviewing the studies, we assessed study duration, number of subjects, whether it was blinded, placebo controlled or open labeled, the measures of clinical efficacy and the assessments of specific and nonspecific bronchial reactivity. The studies were very heterogeneous, and therefore direct comparison and extrapolation of conclusions was difficult. The majority of the studies demonstrated either an improvement in asthmatic symptoms or a decrease in bronchial reactivity to the specific antigen employed, or both. The minority of studies demonstrated no clinical efficacy. The most consistent evidence of benefit was suggested in those trials employing house dust mite therapy, while immunotherapy for grass and cats demonstrated some benefit but the number of studies employing these treatments was very small. There are no trials that provide convincing evidence that immunotherapy with dog and mold antigens is effective for childhood reactive airway disease.

CONCLUSION

Asthma is a multifactorial disease with many triggers. In establishing a role for immunotherapy one must consider all the different aspects such as allergic triggers, environmental stresses, and viral infections. The literature is unclear as to when immunotherapy should be initiated for childhood asthma. While there are suggestions that immunotherapy should be considered for the child with mild or moderate asthma and dust mite sensitivity when pharmacotherapy is not efficacious, the immunomodulatory properties of immunotherapy may actually be more tailored for early intervention in asthma rather than for use once symptoms have occurred. More research is required in order to clarify whether immunotherapy should be recommended more often for the treatment of childhood asthma.

Measurement of serum levels of eosinophil cationic protein to monitor patients with seasonal respiratory allergy induced by Parietaria pollen (treated and untreated with specific immunotherapy)

This trial studied the behavior of a marker of eosinophilic inflammation, eosinophil cationic protein (ECP), in the peripheral blood of two groups of subjects with seasonal allergic respiratory symptoms (rhinitis and mild bronchial asthma) induced by pollen allergens of Parietaria judaica (P.j.) (one group treated and another untreated with specific immunotherapy [SIT]), to determine what contribution these serial measurements might provide, in comparison with various other tools now available for pollinosis monitoring. In a previously randomized order, we selected 25 patients with monosensitization to P.j. pollen allergens; among them, 12 had started SIT with a P.j. extract in autumn 1993. As a control group, 13 patients were untreated. All patients were studied with various tests at four different times: time I-November 1993; time II-February 1994; time III-end of May 1994; and time IV-September 1994. Blood samples for determination of serum ECP were collected at each time. Methacholine challenge tests were performed at times I and III. A pollen count was also carried out. A statistically significant difference (P < 0.05) was observed in mean ECP levels at times I and III in SIT treated and untreated patients. The interaction between groups and time was not significant. No statistically significant difference was found between PD20 FEV1 values at times I and III in either group. After 1 year of treatment, we did not find any effect of SIT on bronchial hyperresponsiveness or on ECP serum values.