Monitoring of mite Dermatophagoides farinae allergen-specific IgG and IgG subclass distribution in patients on immunotherapy

Immunoglobulin G1 subclass responses can be used to detect specific allergy to the house dust mites Dermatophagoides farinae and Dermatophagoides pteronyssinus in atopic dogs

BACKGROUND

In dogs with atopic dermatitis, intradermal testing (IDT) or allergen specific IgE serological testing are routinely employed to identify causative allergens. These allergens can then be used for allergen-specific immunotherapy and allergy management. The clinical relevance of this testing is affected by the source of allergen, and other biomarkers that are more related to specific allergens still need to be identified. The aim of this study was to investigate levels of specific IgE, total IgG, and IgG1 and IgG2 subclasses against the local house dust mites (HDM) Dermatophagoides farinae (DF) and D. pteronyssinus (DP) as biomarkers by using in-house ELISAs in healthy (n = 33) and atopic dogs (AD) (n = 44) that were either positive or negative by IDT to HDM.

RESULTS

Being over 3 years of age was a risk factor for AD (Odds Ratio (OD) = 4.10, 95% Confidence interval (CI) 1.57-10.75, p = 0.0049), but there was no relation to IDT outcomes (OR = 0.9091, 95% CI 0.22-3.74, p = 1.00). High levels of all antibody isotypes (IgE, IgG, IgG1 and IgG2) against HDM were found in aged healthy dogs (> 3 years old). In AD, HDM-IgE and IgG1 levels were higher in dogs that were IDT positive to HDM than in IDT negative animals. Levels of IgE and IgG1 could be used to distinguish the specific allergens, whereas total IgG and IgG2 levels were not different between IDT-positive and IDT-negative AD. By the receiver operating characteristic curve at a false-positive rate = 0.10, both IgE and IgG1 showed better sensitivity than IgG and IgG2. Similar to IgE, serum IgG1 concentration was also relevant to IDT outcomes.

CONCLUSIONS

Our in-house ELISAs coated with local HDM were useful for evaluating antibody levels, and we propose use of the HDM-specific IgG1 subclass as a biomarker to detect HDM specific allergens in AD, potentially together with an IgE based platform.

Antibody levels to Malassezia pachydermatis and Staphylococcus pseudintermedius in atopic dogs and their relationship with lesion scores

BACKGROUND

Elevated immunoglobulin E (IgE) levels to Malassezia or Staphylococcus species in human atopic dermatitis are related to the skin severity index; a similar association has not been reported in atopic dogs.

OBJECTIVES

To investigate serum levels of allergen-specific IgE, total specific IgG and IgG subclasses (IgG1 and IgG2) for M. pachydermatis and S. pseudintermedius, and to correlate them with the severity of dermatitis in dogs.

ANIMALS

Serum samples were collected from dogs categorized by age and disease status. Groups 1 and 2: <3-year-old healthy (n = 9) and atopic dogs (n = 9), respectively; and groups 3 and 4: ≥3-year-old healthy (n = 11) and atopic dogs (n = 14), respectively.

METHODS AND MATERIALS

Antibody levels were measured by ELISA. The Canine Atopic Dermatitis Lesion Index (CADLI) was analyzed in relation to antibody levels.

RESULTS

Specific IgE and total IgG against M. pachydermatis and S. pseudintermedius were significantly increased in atopic dogs of all ages. Although differences between atopic and healthy dogs, with regard to specific IgG1 and IgG2 levels to each microbe, varied in significance within age groups. No significant relationships were found between the CADLI and any specific immunoglobulin levels for both microbe types.

CONCLUSIONS AND CLINICAL IMPORTANCE

In dog skin, microbes may act as allergens triggering inflammatory responses via IgE- and IgG-dependent pathway(s). The affinity of the IgG subclass produced may vary according to antigen type. Specific IgE levels may be related to clinical disease in dogs and not to skin lesion severity.

Inmunoterapia con alérgenos, ¿cuándo y por qué?

La inmunoterapia específica con alérgenos es el único tratamiento que modifica el curso natural de algunas enfermedades alérgicas como asma, rinitis, conjuntivitis, dermatitis atópica y alergia al veneno de himenópteros. Sin embargo, aún existe cierta controversia respecto a su seguridad y su utilidad clínica. En el presente artículo se presenta una revisión de los mecanismos moleculares, las indicaciones y contraindicaciones de dicha inmunoterapia, y se evalúan su seguridad y eficacia en cada una de estas enfermedades mediante casos ilustrativos y una breve revisión del tema.

Clinical and immunological changes of immunotherapy in patients with atopic dermatitis: randomized controlled trial

Background. Immunotherapy has proven to be an useful tool in the management of allergic respiratory diseases; however, little has been studied in atopic dermatitis. Objective. To evaluate the clinical and immunological impact of immunotherapy with mites allergen extracts in atopic dermatitis. Methods. Patients with atopic dermatitis were assigned with computer-generated randomization to either of the following groups: (a) controls received only topical treatment with steroids and/or tacrolimus and (b) actively treated patients received topical treatment plus immunotherapy. Levels of serum total IgE, mites-specific IgE and IgG4 were assessed at study start and after one year of immunotherapy. Results. 31 patients in the active group and 29 in the control group completed the study. Symptoms and medication scores were significantly reduced in the active group after six months. Three patients in the control group showed new sensitizations to mites, while 3 patients in the active group showed neosensitization to shrimp with negative oral food challenge. We observed significant increase of mites-specific IgG4 levels in active group. Conclusion. Specific allergen immunotherapy induced a tolerogenic IgG4 response to mite allergens associated with favorable clinical effects in atopic dermatitis patients.

Clinico-immunologic study on immunotherapy with mixed and single insect allergens

BACKGROUND

Immunotherapy (IT) is practiced mainly with mixed and single allergen vaccines. But studies are rare with mixed allergen preparations.

OBJECTIVE

The objective of this study is to study mix and single insect allergen IT in patients of allergic rhinitis and asthma.

METHODS

We performed a double-blind placebo-controlled trial of mix and single allergen IT for 1 year in 99 patients of asthma or rhinitis or both. There were two groups, (1) active allergen IT (n = 61) with three subgroups single insect extract (cockroach, housefly, or mosquito) and mix allergen IT (two or three insect extracts) and (2) placebo (n = 38). Clinical (skin reactivity, airway reactivity, and symptom score) and immunological (IgE/IgG4 and IgG1/IgG4 ratio) parameters were assessed at baseline and after 1 year of IT.

RESULTS

Eighty-five patients completed 1 year of IT. The active allergen IT group patients showed a significant improvement compared to baseline values (p < 0.05) and placebo group patients (p < 0.05) with regard to symptom scores, FEV1 values, and immunological parameters (IgG4). No significant difference was found between mixed and single IT group patients for changes in clinical and immunological parameters. Positive correlation was observed between increase in IgG4 and clinical improvement. The changes in above parameters in placebo group were nonsignificant after 1 year of treatment.

CONCLUSION

IT with two to three mix extract from the same allergen group is effective for insect hypersensitivity.

Clinical improvement and immunological changes in atopic dermatitis patients undergoing subcutaneous immunotherapy with a house dust mite allergoid: a pilot study

BACKGROUND

House dust mites (HDMs) represent significant indoor allergen sources for patients with atopic dermatitis (AD). Subcutaneous allergen-specific immunotherapy (SCIT) has been shown to be successful in patients with allergic rhinitis and mild asthma and might represent an attractive therapeutic option for the long-term treatment of HDM sensitizations in AD patients. However, only a few studies have been conducted on the effectiveness of HDM SCIT in AD, resulting in controversial clinical results. Data on immunological changes induced by SCIT in AD patients are rare.

OBJECTIVES

We performed an open pilot study to assess clinical changes and objective laboratory parameters and evaluate the benefit of HDM SCIT in 25 AD patients with IgE-mediated sensitization against HDM.

METHODS

The severity of AD was evaluated by the severity scoring of atopic dermatitis system (SCORAD). Specific IgE and IgG4 against HDM and serum levels of TARC/CCL17, MDC/CCL22, IL-16, IL-4, IFN-gamma, IL-10 and TGF-beta1 were measured during SCIT.

RESULTS

Subjective and objective SCORAD improved significantly within only 4 weeks of treatment. The level of the tolerogenic cytokine IL-10 increased, whereas CCL17 and IL-16 decreased in the sera of the patients during SCIT. Allergen specific IgE decreased, while IgG4 increased during SCIT.

CONCLUSION

In this open-label pilot study, SCIT with an HDM extract in patients with AD led to a significant improvement of AD mirrored by a reduction of SCORAD as well as serological and immunological changes, which might serve as valuable parameters to estimate the therapeutic effect of SCIT.

Serum ovalbumin-specific immunoglobulin G responses during pregnancy reflect maternal intake of dietary egg and relate to the development of allergy in early infancy

BACKGROUND

The value of allergen elimination diets during pregnancy for primary prevention of infant allergy has been questioned. However, dietary compliance may influence effectiveness.

OBJECTIVES

To monitor egg intake during a randomized controlled trial of egg avoidance throughout pregnancy and lactation by serial measurements of serum ovalbumin (OVA) IgG concentration in conjunction with dietary diary record and also, to analyse specific IgG concentrations at birth in relation to infant allergic outcome.

METHODS

Pregnant women, with personal or partner atopy, were randomized to complete dietary egg exclusion or an unmodified healthy diet before 20 weeks gestation. The infants were evaluated for atopy at 6 months of age. Serum food-specific IgG concentrations were determined by ELISA in maternal samples collected at study recruitment and during labour, and in infant samples at birth (umbilical cord).

RESULTS

Serum-specific IgG to OVA, but not the unrelated allergen, cow's milk beta-lactoglobulin, decreased over pregnancy in egg-avoiding women only (P<0.001). Cord OVA IgG concentration correlated with maternal IgG at delivery (r=0.944; P<0.001), and for infants born to atopic women, cord concentration was higher than that of their mother's (P<0.001). Infants with the lowest and highest cord IgG concentrations were the least likely, and those with mid-range concentrations were the most likely, to be atopic by 6 months of age (P=0.008).

CONCLUSION

Serum OVA IgG concentration reflects egg consumption, thereby indicating dietary allergen doses to which the developing immune system might be exposed. Trans-placental maternal IgG must be considered among early life factors that regulate infant atopic programming.

Allergen-specific immunotherapy for allergic rhinitis: a new insight into its clinical efficacy and mechanism

Immunotherapy has been used widely for allergic diseases for more than 90 years but, in the opinion of many physicians, it is still a controversial form of treatment. The exact mechanism of action of immunotherapy remains to be determined. In the present study, we review the clinical efficacy and mechanism of action of immunotherapy for allergic rhinitis. Recent double-blind placebo-controlled studies have demonstrated the clinical efficacy of immunotherapy for allergic rhinitis. This therapeutic method has several advantages over conventional pharmacological treatment. Immunotherapy is inferior to pharmacological treatment in the short term, but in the long term it is substantially superior with respect to clinical efficacy. Immunotherapy has the potential permanently to alleviate the abnormal immunological responses of allergic rhinitis and to cure the nasal symptoms in the long term, even after discontinuation of injections. In addition, immunotherapy can prevent the onset of new sensitizations in allergic patients and may prevent the progression of rhinitis to asthma. It may therefore be possible for immunotherapy to alter the natural history of allergic sensitization and its clinical manifestation. These lines of clinical evidence could affect strategies of long-term therapy for allergic rhinitis. Modern molecular biological techniques have suggested that immunotherapy may affect allergen-induced TH responses or cytokine profiles, but there is no general agreement among investigators. However, IL-5 is likely to be the most important cytokine involved in the clinical efficacy of immunotherapy, and the suppression of allergen-induced IL-5 synthesis is most likely to be involved in the mechanism of immunotherapy. Our recent investigations, focusing on specific IgE and IgG4 responses, suggest that immunotherapy-induced changes in these specific antibodies play a clinical role and are involved in the mechanism of action of immunotherapy. It is probable that immunotherapy modulates and affects many different immunological and non-immunological phenomena to produce clinical efficacy and that clinical improvement is a consequence of different mechanisms over time.

Significant correlation between symptom score and IgG4 antibody titer following long-term immunotherapy for perennial allergic rhinitis

Although there is evidence of some measure of clinical benefit as well as immunologic change during the early phase of immunotherapy, a sustained clinical response is only possible with prolonged therapy. Immunotherapy has to be administered for about 3 to 5 years for such sustained clinical efficacy. This study aimed at investigating the dynamics of IgE and IgG4 antibodies after more than 5 years of immunotherapy, to examine the statistical correlation between these antibodies and symptom scores. Our study demonstrated that the allergen-specific IgE antibody level significantly decreases and the IgG4 antibody level significantly increases following immunotherapy. However, the percent decrease in IgE antibodies did not correlate with the percent decrease in symptom scores. On the other hand, the percent increase in IgG4 antibodies correlated with the percent decrease in symptom scores. We infer that an elevation of IgG4 antibodies is not simply an epiphenomenon unrelated to the underlying working mechanism of clinically successful immunotherapy, but probably makes an active contribution to symptom relief.

Immunotherapy with standardized extract of Dermatophagoides pteronyssinus in bronchial asthma: a dose-titration study

According to the maximum tolerated dose (MTD) achieved, we assessed the changes in clinical and laboratory parameters, induced by specific immunotherapy (SIT), in a group of 43 asthmatic patients sensitized to Dermatophagoides pteronyssinus, over a period of 18 months. A standardized extract (100 Bu/ml; 40 micrograms/ml of Der p 1; 20 micrograms/ml of Der p 2) was used. The patients were divided into two groups: the high-dose immunotherapy (HDI) group (MTD > or = 4 micrograms Der p I) and the conventional immunotherapy (CI) group (MTD < 4 micrograms Der p 1). Changes in clinical severity index, medication, and symptom scores; in cutaneous and conjunctival reactivity; and in the levels of specific IgE, IgG, IgG1, and IgG4 to D. pteronyssinus (Der p 1 and Der p 2) were measured (ELISA monoclonal antibodies). Safety was monitored according to the EAACI guidelines. The range of the MTD was 0.8-16 micrograms of Der p 1. Ninety percent of the patients tolerated a dose of 3.2 micrograms, but only 18% of the patients reached a maintenance dose of 16 micrograms. The medians of the accumulated dose were 197 micrograms of Der p 1 for the HDI group, and 50 micrograms for the CI group. Conjunctival and cutaneous reactivity was significantly lowered (P < 0.001) after SIT, as were the clinical severity score and medication score in both groups, without significant differences between the groups, except for cutaneous reactivity. Levels of specific IgE decreased significantly (P < 0.01) in both groups, again without significant differences between the groups. The range of the increase in medians of specific IgG, IgG1, and IgG4 was 4.4-120-fold for the HDI group and 3-24-fold for the CI group (P < 0.01). The increase in the levels of Der p 1 and Der p 2 IgG4 were correlated to the changes in cutaneous and conjunctival reactivity (P < 0.01). These results show that a maintenance dose of 3.2 micrograms Der p 1 (8 BU) can induce pronounced clinical and immunologic changes with an excellent safety profile.

Allergy to cockroaches in patients with asthma and rhinitis in an urban area (Madrid)

Previous studies have established that cockroach allergens are important sensitizing agents in the induction of rhinitis and asthma principally in urban areas. This study was undertaken to assess skin test reactivity and specific IgE antibody reactivity to extracts of Periplaneta americana (P.a.), Blattella germanica (B.g.), B. orientalis (B.o.), and a fecal extract of B. germanica (FEB.g.) in a group of patients with rhinitis and asthma living in an urban area in Europe. We examined clinical characteristics and aerollergen sensitivities of 171 consecutive Madrid urban patients with rhinitis and asthma who met the criteria for the study. A comprehensive clinical evaluation was followed by skin prick test with common allergens and saline extracts of P.a., B.g., B.o., and FEB.g. and measurement of serum specific IgE antibody to cockroach extracts. The age of patients ranged from 7 to 68 years (mean 20.4 +/- 16). A total of 153 (90.5%) subjects were atopic and 19 (10%) were considered nonallergic. Pollen sensitivity (66.5%) was most prevalent, distantly followed by sensitivity to cockroach (25.7%), mite (20%), cat (15.5%), Alternaria alternata (14.5%), dog (14%), and food (2%). Skin test reactivity to cockroach extracts was 37 (21.6%) to B.o., 20 (11.6%) to P.a., 19 (11.1%) to B.g. and five (2.9%) to FEB.g. Twenty-one of these patients had rhinitis, 19 rhinitis and asthma, and one only asthma; 26 had perennial symptoms, while 16 had seasonal (spring) symptoms; three (1.7%) patients had only positive prick test to cockroach; all had perennial rhinitis and/or asthma. Eighteen (10.5%) patients had specific serum IgE (RAST 1 or 2) to B.o., 13 (7.6%) to P.a., and six (3.5%) to B.g. Eighty (46.7%) patients had visual evidence of cockroach infestation in their home, mostly B.o.; 31 had positive prick test to cockroach (P < 0.0003). The results indicate that sensitivity to outdoor allergens (pollen) is more prevalent than to indoor allergens. Cockroach sensitization is the most important indoor allergen in our area, and B.o. accounts for most cockroach sensitization.

Peptide-mediated regulation of the allergic immune response

A major key to successful immunotherapy may depend on altering the qualitative nature of the immune response in allergic patients. In this review we examine how immune responses to environmental allergens are regulated, and the mechanisms used by the immune system to prevent allergic sensitization. We also discuss future prospects of using allergen-derived peptides in immunotherapy and the possibility of 'reprogramming' the immune responses by immunizing under conditions that promote Th1 responses instead of Th2 responses.

IgG1 and IgG4 antibody responses to the dust mite Lepidoglyphus destructor in a naturally exposed farming population

The natural humoral immune response to the dust mite Lepidoglyphus destructor was assessed by comparing the IgG1 and IgG4 responses elicited in allergic (n = 44) and healthy (n = 16) individuals in a farming population chronically exposed to this allergen. With the aid of an immunoblotting technique and ELISA, the sera were analyzed for anti-L. destructor antibodies. While the majority of sera from the allergy group displayed several bands for both IgG1 and IgG4, the nonatopic healthy group was negative as analyzed in immunoblotting. When they were analyzed in ELISA, there was a significantly higher response in the allergy group than in the healthy group for IgG4, but not for IgG1. Taken together, these results imply that the immune system of individuals spared from allergic reactions to L. destructor not only lacks IgE antibodies but also seems largely to "ignore" these allergens/antigens despite exposure.

Effects of immunotherapy with a purified standardized allergen preparation of Dermatophagoides farinae in adults with perennial allergic rhinoconjunctivitis

Immunotherapy (IT) was performed for 12 months with a purified and standardized preparation of Dermatophagoides farinae. Twenty adults with rhinoconjunctivitis sensitive to house-dust mite were given IT, and a similar group of 11 patients served as open controls. A total of 512 injections were given. Twenty-eight episodes of allergic side-effects occurred, 13 general and 15 local, most of them during the initial incremental dose period. No severe reactions started later than 30 min after the injection. One patient suffered anaphylactic shock. In this patient, specific antibodies fell immediately, followed by an increase within 1 week. The therapy group improved significantly in relation to the open controls in patients' subjective evaluation of symptoms (P < 0.028) and skin (P < 0.0001) and conjunctival (P < 0.001) sensitivity. Specific IgE increased in controls (P < 0.0001) but not in IT-treated patients during the "mite season"; that is, there was a significant difference in change during the observation period (P < 0.0001). There was also a difference in change of specific IgG between the groups during the first 4-5 months and the whole year (P < 0.0001), but not from 4-5 months to 12 months. In contrast to changes in antibody titers (IgG, P = 0.04), changes in conjunctival (P < 0.01) and especially skin sensitivity (P < 0.005) correlated well with subjective improvement. This implies that the skin prick test and the conjunctival test can be recommended for follow-up of IT.(ABSTRACT TRUNCATED AT 250 WORDS)

Booster immunotherapy (BIT)

This study tries to answer two questions: 1) how long does the therapeutic effect of successful immunotherapy (IT) last after termination of the treatment? and 2) what is the best treatment for recidivist patients? To answer the first question, we asked 108 patients with rye/grass pollen allergy who had previously undergone IT for 3-4 years and had responded well to treatment to complete a questionnaire on the course of their recovery after termination of the therapy. Evaluation of the answers revealed a recidivist rate of approximately 30% in the first 3 years. According to our results, the risk of a relapse after this period seems to be low. To answer the second question, we included 40 patients suffering from type I allergy to grass/rye pollen in a clinical study. Each of them had previously undergone specific IT with a grass pollen extract mixture and had terminated this therapy after 3-4 years practically free of symptoms during the grass pollen season. As the symptoms returned and increased from year to year after the end of IT, new therapeutic steps had to be considered. We investigated the efficacy of a short preseasonal injection treatment called "booster immunotherapy" (BIT). BIT was performed with two different injection-regimens, a low-dose schedule comprising six injections and a high-dose schedule with 11 injections, in both cases administered as a build-up regimen. In the next pollen season, 28/40 (70%) patients reported strong improvement or even complete remission of the allergy symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Modern concepts of immunotherapy

Although common allergies have been considered as immediate IgE antibody mediated responses, attention is now turning to inflammatory responses that appear to be initiated by T-cell responses to peptides from allergens presented in combination with HLA class II molecules. Although classic immunotherapy with allergen extracts has been found to downregulate these T-cell responses, more efficient and safe methods are being sought.