A review of immunotherapy

Stability of allergen extracts used in skin testing and immunotherapy

PURPOSE OF REVIEW

The present article reviews allergen extract stability applied to US manufactured products. Methods used to measure potency of extract concentrates, patient prescription dilute extracts, and mixes containing degrading enzymes will be discussed.

RECENT FINDINGS

Information about the allergen extract active ingredient components contributing to potency is increasing. Pertinent stability issues include the type of diluent used for extraction and mixing. Fifty percent glycerin greatly extends the time over which extracts remain potent, including in mixes with fungal and insect extracts known to contain protein-degrading enzymes. Diluents that contain additional protein content such as human serum albumin increase stability of dilute solutions. Many of the most rigorous studies on allergen stability have been performed by allergenic extract manufacturers in support of Food and Drug Administration approved dating for standardized products and are not published.

SUMMARY

Studies addressing how antigens in extracts change under various storage conditions have provided general guidance for expiration dating, but the diversity of extracts and testing methods have been less than complete. Additional findings that are increasing our knowledge of extract shelf life will be discussed.

Development of the allergy outcome survey for allergic rhinitis

The Allergy Outcome Survey (AOS) is a reliable measure used to monitor patients with allergic rhinitis. It was developed for and included in the Outcomes Measures of Immunotherapy in Allergic Rhinitis (OMIAR-1) project, designed to study the benefits of immunotherapy in the treatment of allergic rhinitis. Preliminary results indicate that AOS is specific, brief, reliable, and easy to use. Also, it is useful for evaluating change with therapy and can be used alone as a performance metric or in combination with other measures as part of a more complete outcomes monitoring system. As the OMIAR-1 study progresses, more information will be available on the advantages and limitations of the AOS.

Monomeric chemically modified allergens: immunologic and physicochemical characterization

Allergenic extracts (Der p, grass, and Parietaria) or single allergens such as Par j I (the major allergen of Parietaria) and ovalbumin (OA), a food allergen widely used in animal models, were chemically modified by reaction with potassium cyanate (KCNO), which transforms the epsilon-amino group of the lysine of proteinaceous allergens into ureido groups. KCNO-modified (carbamylated) allergens have low allergenic potency, as demonstrated in vitro (RAST inhibition) and in vivo (passive cutaneous anaphylaxis). When used to immunize rabbits, carbamylated allergens still induce IgG antibodies able to cross-react with native allergens (immunoblotting experiments). An interesting feature distinguishing carbamylated allergens from other chemically modified allergens is the preservation of the native monomeric dimension as demonstrated by SDS-PAGE analysis. Results are discussed from the perspective of clinical application of carbamylated allergens.

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

House dust mite D. farinae and Der f II-specific IgG and IgG subclass responses were evaluated in 32 adults with perennial rhinitis undergoing immunotherapy for 1 year by means of IgG-RAST and ELISA. The ELISA method, which is based on subclass-specific monoclonal antibodies, could detect 0.5-1.5 ng/ml of specific antibodies. D. farinae and Der f II-specific IgG4 antibodies increased continuously as immunotherapy proceeded, while total IgG and IgG1 antibodies reached a plateau value 6 months after the start of immunotherapy, followed by a slow decrease during maintenance therapy. During the early phase of treatment the concentration of IgG1 and IgG4 antibodies rose, even though the increase of IgG4 antibodies dominated. The positive clinical outcome as measured by the decrease in conjunctival sensitivity was associated with an increased ratio of specific IgG4/IgG1 antibodies as well as the magnitude of the IgG4 subclass response. Quantitation of IgG subclass antibodies in patients undergoing immunotherapy may be of some clinical value, but the clinical usefulness needs to be demonstrated for each type of allergen and possibly also for each assay system.

IgE, IgG, IgG1 and IgG4 patterns in yellow jacket allergic patients during immunotherapy with a venom depot extract

Using immunoblot studies, detailed antibody patterns were performed with the sera of 10 yellow jacket allergic patients undergoing specific immunotherapy with a yellow jacket venom SQ-depot extract (ALK, Denmark). Five males and five females (age range 10-65, mean 48 years) were investigated. All patients had a history of systemic reactions after an insect sting and a positive skin-prick test at a dose of at least 100 micrograms/ml yellow jacket venom. Yellow jacket venom (ALK) was separated on a 7.5-20% SDS-PAGE, transferred to nitrocellulose (NC), and then the NC-strips were incubated with the patients' sera. For detection of IgE, IgG, IgG1 and IgG4, an alkaline phosphatase linked 2nd antibody was used. Prior to immunotherapy, a strong IgE binding was detected at 25 kD in nine of 10 patients, representing Antigen-5 (Ag-5) as major allergen. Reactivity to this antigen was also present with the other immunoglobulin classes, although not as marked. In addition, a second frequent IgG and IgG1-binding band was seen at 35 kD (phospholipase A). Only weak or no binding to this band was found with IgE and IgG4. Binding to hyaluronidase (43 kD) was seen only in three cases. During immunotherapy, a significant increase in IgG and particularly IgG4 staining was found with Ag-5, whereas hyaluronidase induces mainly an IgG1 response and phospholipase A showed only a weak IgG response. In addition, the formation of new IgG4 binding to proteins in the region of about 70-90 kD was found in most patients. The dose necessary for the induction of this antibody formation was greater than or equal to 150.00 SQ yellow jacket venom.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of IgE-binding activity in serum after intranasal treatment of normal rabbits with P. judaica extract

Local intranasal immunotherapy relieves the allergic symptoms of rhinitic patients but little is known about the absorption and distribution of inhaled allergens in the body. The aim of this study was to establish whether allergenic proteins are able to reach the bloodstream by penetrating through the nasal mucosa when aqueous P. judaica extract was administered into the nostrils of normal rabbits. Optimal conditions for a sensitive modified RAST (immunocapture RAST) were set up and the method was used to detect clinically relevant allergenic activity in the systemic circulation. The kinetic profile after intranasal treatment was compared with the profile after intravenous injection of the allergenic extract. The findings are discussed in relation to the mechanism by which local immunotherapy acts.

Detailed IgG and IgE antibody patterns during immunotherapy with honey bee venom

Fourteen patients with a known honey bee venom (HBV) allergy were followed during 1-2 years of immunotherapy. HBV-specific IgG antibody levels increased in all patients but one. HBV-specific IgE antibodies decreased slightly during the first year of therapy. The ratio HBV-specific IgG-/IgE showed a marked increase during the first year for most of the patients, and a further increase during the second year in the four patients followed that long. As could be expected an increased radiostaining was found after 1 year of treatment to all important allergens in IgG CRIE, but after 2 years a sustained or increased radiostaining was obtained to phospholipase (PLA) alone. A decreased radiostaining might more easily be seen with weaker immunogens.

Clinical and immunological effects of oral immunotherapy with a standardized birch pollen extract

Oral immunotherapy (IT) was evaluated in a pilot study in two centres in children aged 8-15 years with allergic rhinoconjunctivitis. High doses (up to 20 X 10(6) BU monthly) of a defined freeze-dried birch pollen extract administered in enteric-coated gelatine capsules were given either daily for seven consecutive days every month or once weekly. Symptom scores, as assessed by sneezing, dripping and blockage of the nose, and redness, itching and swelling of the eyes, were significantly lower in treated patients compared to untreated, or placebo treated controls after 3 to 5 months of therapy. In all the 16 treated, but only in three of eight untreated patients, the scores were lower during the pollen season 1982 than during the pollen season preceding the treatment period, despite comparable pollen counts during the two seasons. One year after beginning treatment the reactivity in conjunctival provocation tests was decreased about 10-fold (P less than 0.001) in the patients receiving more than 2 X 10(5) BU monthly compared to about two-fold in patients receiving lower doses, or placebo. Increased levels of IgE antibodies directed against birch pollen were recorded in the serum and saliva of most patients after 3-4 months of active IT. In contrast, IgG antibody responses were poor in most of the patients. Side effects, particularly from the gastrointestinal tract, appeared in all treated children. In one of them a systemic reaction occurred during IT. The study indicates that properly performed oral IT with a potent birch allergen extract in enteric-coated capsules may be effective.

IgG and IgE antibody patterns after immunotherapy with monomethoxy polyethyleneglycol modified honey bee venom

Antibody responses to honey bee venom (HBV) were studied in 13 patients during a 4-month course of immunotherapy with monomethoxy polyethyleneglycol (mPEG) modified venom. There was a rise of HBV-specific IgG antibodies as measured by IgG-RAST in all patients and a slight decrease of IgE antibody in most of them. The IgG-antibody responses during mPEG-HBV treatment as examined by crossed radioimmunoelectrophoresis were directed to phospholipase A, hyaluronidase, acid phosphatase and to another allergen, antigen 1. Thus, despite a high degree of mPEG-modification of HBV, the immunogenicity of the most important HBV allergens was retained.

Clinical and biological evaluation of semi-rush and ordinary immunotherapy schemes in type I allergic respiratory diseases

Forty-three patients with type I allergic respiratory diseases received aqueous grass pollen immunotherapy in a prospective study designed to compare the clinical and biological effects of a semi-rush hyposensitization (20 patients) with ordinary hyposensitization (23 patients). Before the start of the therapy (end of previous grass pollen season, t1) and before (t2) and after the next grass pollen season (t3), total serum IgE (tIgE), grass pollen-specific IgE (GPsIgE), grass pollen-specific IgG (GPsIgG) and complement factors C3 and C4 were determined. GPsIgE and GPsIgG levels increased significantly more during immunotherapy in patients receiving the semi-rush scheme as compared with the ordinary scheme. There were no significant changes between the two schemes at any times for tIgE, C3 and C4. GPsIgG was already higher in allergic patients before the start of therapy as compared with non-allergic patients and controls. Clinical improvement was the same in patients treated with the semi-rush scheme as in the ordinary group. The number of side effects was not statistically different between the two groups. In neither group was there a correlation between the change in biological parameters and change in clinical symptoms. As the semi-rush scheme gives the same results immunologically as well as clinically, it could be used in a number of patients since it reduces the time course of the initial therapy by about 2 months.

Immunotherapy with alginate-conjugated and alum-precipitated grass pollen extracts in patients with allergic rhinoconjunctivitis

In order to compare the safety and the efficacy of two grass pollen extracts made from the same starting material, i.e. equal proportions of cocksfoot and timothy, a 3-year study was made on patients with hay fever. One product was a dialysed aqueous extract of pollens which was chemically conjugated to activated sodium alginate ( Conjuvac ). The other was a pyridine-extracted alum-precipitated crude extract (Allpyral). Forty patients with classical hay fever were admitted to the study. All gave positive result to prick and nasal/conjunctival testing with extracts of both cocksfoot and timothy grass. Thirty-five patients completed all 3 years of the study. Seventeen/eighteen Allpyral-treated and 17/17 Conjuvac -treated patients were subjectively improved. There was no significant difference in symptom scores between the two groups. Challenge tests showed a tendency to reduced sensitivity to allergen in the Conjuvac -treated but not in the Allpyral-treated group. The median values for specific IgG and IgE showed the same pattern of reaction as seen in earlier studies of pollen hyposensitization. There was, however, a greater increase of grass-specific IgG in the Conjuvac -treated patients. No serious adverse effects were seen in any of the treatment groups, but there were slightly fewer side effects in the Conjuvac group.

Blood lymphocyte proliferation response to pollen extract as a monitor of immunotherapy

In a study of immunotherapy 41 children with seasonal rhinoconjunctivitis due to deciduous tree pollen allergy were monitored by means of symptom scoring, patient self-evaluation, conjunctival provocation tests and lymphocyte proliferation in vitro to the allergen. The lymphocyte responsiveness to birch pollen decreased significantly during the first year of immunotherapy. However, neither the lymphocyte responsiveness before treatment nor changes in lymphocyte reactivity during the immunotherapy correlated with the clinical efficacy of the therapy as evaluated by changes in symptom scores, self-evaluation or conjunctival provocation test changes in the individual patients. The results indicate that lymphocyte responsiveness to an allergen cannot be used to select patients for immunotherapy, i.e. to predict whether a patient would benefit from immunotherapy or not, or to evaluate the effects of immunotherapy after beginning the treatment. However, lymphocyte proliferation response to an allergen indicates clinical sensitivity.

A nylon ball solid-phase radioimmunoassay for specific antibodies in human sera. Application to measurement of IgG antibodies to pollen allergens

The principle of the radioallergosorbent test (RAST) has been used to measure IgG antibodies to timothy grass pollen allergens in sera from desensitized allergic subjects. 125I-labeled goat anti-human IgG was used as detector protein. Non-specific binding was eliminated by use of a non-porous nylon ball an antigen carrier and by use of a special buffer with high ionic strength and pH, containing 1% bovine gamma globulin and 5% normal rabbit serum as 'balance proteins'. At dilution 1:80 non-specific binding was only 0.28% and the binding ratio for a high-liter serum was about 10. By inhibition experiments the assay was demonstrated to be specific for IgG antibodies to timothy grass pollen. The results obtained with this assay correlated statistically significantly with those found th a double -antibody method (rs equal 0.68, n equal 20, t equal 3.93, P less than 0.001). Serum dilution curves were parallel, indicating that the assay is in allergen excess. The within-assay coefficient of variation ranged from 3.9 to 7.6%; the between-assay coefficient of variation from 8.4 to 19.5%. The assay is very simple to perform, requiring no centrifugation. The allergen-coated balls are stable for at least 3 months. The assay should be applicable to measurement of IgG antibodies and IgG subclass antibodies to any protein antigen of interest.

Clinical effects of hyposensitization using a purified allergen preparation from Timothy pollen as compared to crude aqueous extracts from Timothy pollen and a four-grass pollen mixture respectively

Most extracts used in hyposensitization are complex and ill-defined mixtures of a large number of antigenic components. A highly refined (purified) and well-characterized allergen preparation from Timothy pollen (Phleum pratense) is now available. This paper describes the results of hyposensitization for 3 years comparing the purified preparation Timothy N, the crude extract Timothy O and a four-grass mix in sixty patients with allergic rhinitis due to grass pollen. The sixty patients were randomized into three groups and compared with a control group not hyposensitized. All three groups showed a significant decrease in clinical symptoms compared with the control group. The Timothy N group had a significantly higher nasal tolerance shown by nasal challenge test after 3 years' treatment than the group treated with the crude extract (P = 0.05). In addition, the Timothy-N-treated patients needed significantly less antihistaminic medication than the patients having received the crude extract or the four-grass mix (P = 0.02 and P = 0.01, respectively).

Estimation of affinity and quantity of human antigen-specific serum IgG (blocking antibodies)

An assay for estimation of quantity and quality of antigen-specific IgG against two purified antigens from cow hair and dander is described. The substance concentration of antigen-specific IgG was more than 10 times higher in serum from immunized patients than in serum from non-immunized patients. Almost the same KA values of 5 x 10(9) l/mol were calculated for IgG in sera from immunized and non-immunized patients with allergic asthma to cow hair and dander.

Influence of preseasonal treatment with L-tyrosine-adsorbed allergoids on IgE-mediated histamine release from basophils of children suffering from allergic diseases

In 10 children suffering from allergic pollinosis and/or asthma, a preseasonal hyposensitization scheme with 3 weekly injections of a glutaraldehyde-modified, tyrosine-adsorbed grass-pollen allergen reduced the histamine release from basophils in response to increasing concentrations of antigen. The decrease in histamine release which occurred 1 week after the injection course was even maintained during the pollen season. The inhibition was only obtained when basophils were incubated with the serum of patients, but not with the serum of normals, indicating that blocking antibodies may have occurred. In contrast to what has been observed in the treated patients' group, 5 patients, who were not included in the hyposensitization scheme, showed identical histamine release curves during the whole investigation period. Specific IgE did not increase after the treatment course and shows the same behaviour as the untreated patients. Thus, as treatment with glutaraldehyde modified, tyrosine-adsorbed allergoids is safe to administer, requires only 3 injections, reduces histamine release from basophils by production of "blocking" antibodies, it appears to be a useful tool in the hyposensitization treatment.

Hyposensitization in childhood hay fever. A comparison of refined and whole timothy extracts

Thirty-six children with well-defined criteria for hay fever (mean age 8 and range 4-15 years) were allocated at random for hyposensitization (HS) with a refined (R) or whole (W) timothy pollen extract during 3-4 years. HS was performed as rush HS with the patients hospitalized for about 1 week and thereafter with monthly injections. Scores for symptoms and antihistamine use were recorded during the season before HS and all seasons during HS. Skin and conjunctival tests were made at the start of HS and postseasonally. Blood samples for IgE and IgG measurements were drawn before and during rush HS and pre- and postseasonally each year. The R-group patients tolerated a higher allergen dose at the end of the rush HS than the W-group ones. They also demonstrated a higher, significant increase in total and specific IgE levels within 7 days and specific IgG levels within 60 days after the start of HS. In both groups postseasonal increases in total and specific IgE levels were seen. The IgG levels increased successively during the treatment. The most remarkable difference between the groups was in scores for symptoms and antihistamine use, which in group R decreased significantly while they increased significantly in group W. Based on these data we recommended that HS, if indicated, should be performed with purified allergen extracts.

Hyposensitization. Comparing a purified (refined) allergen preparation and a crude aqueous extract from timothy pollen

Most extracts used in hyposensitization (immunotherapy) are complex and ill-defined mixtures of a large number of non-antigenic and antigenic components, only a few of the latter being of significance for allergy and allergen specific immunotherapy. A new purified and well-characterized allergen preparation from timothy pollen is now available, and it has been shown to be superior to the corresponding crude aqueous extract in the diagnosis of IgE-mediated human allergy to timothy pollen. This paper describes the results of hyposensitization for 2 years, with the purified preparation and the crude extract compared. The changes in in vivo and in vitro tests following this treatment in 40 patients with allergic rhinitis due to grass pollen are reported. Both patient groups showed a significant decrease in clinical symptom scores when compared with a control group during the grass pollen season. For all groups the symptom scores correlated well with atmospheric pollen counts. Nasal challenge tests showed a significant increase in nasal tolerance to timothy pollen after 2 years of treatment, but nasal tolerance was unchanged in the control group. Nasal function as a criterion for evaluating the effect of specific hyposensitization is discussed. Serum concentrations of timothy pollen-specific IgE antibodies showed a significant decrease for the group treated with the purified preparation and a slighter and non-significant reduction for the other treated group. There was no significant change in total serum IgE levels. The results indicate that the purified preparation is preferable to the crude aqueous extract in hyposensitization.

A prospective national study of the safety of immunotherapy

A prospective study was made in France to determine the frequency, nature, causes and consequences of systemic reactions occurring during specific immunotherapy. One hundred and fifty five reactions were recorded in 151, 997, injections given to 19,739 patients; a percentage of 0.1. It was higher with pollen extracts (0.2%) and practically nil with other extracts (house dust, Dermatophagoides, insect body, bacteria). Asthma, spasmodic rhinitis and urticaria were the most frequent, 80% of systemic reactions. In 59% no explanation could be found. The main known causes of adverse reactions were excessive doses of antigen, improper timing of treatment or incorrect technique of injection. After appropriate treatment the immunotherapy was continued in nearly 90% of the cases. Specific immunotherapy with the majority of extracts now being used, namely adsorbed extracts, is not dangerous but it must be precisely and cautiously done because errors are responsible for nearly 50% of the recorded systemic reactions.

Specific hyposensitization in atopic dermatitis

Specific hyposensitization is rarely advocated for the treatment of atopic dermatitis. Good results have been obtained in fifteen mainly adolescent and adult patients selected from over 3,000 patients with atopic dermatitis. Criteria included a history of exacerbations of the dermatitis after exposure to the antigen, an airborne antigen which could not be avoided, a rather distinctive clinical picture and symptoms bad enough to warrant the considerable difficulties involved.

Immunotherapy in spring-time hay fever. A clinical and immunological study comparing two different treatment extract compositions

In a study of the efficacy of two different treatment schedules for perennial immunotherapy, 47 adult patients with spring-time hay fever due to allergy against birch and other deciduous trees were randomly assigned to three treatment groups: one group received birch, alder and hazel allergen in Allpyral, another group received the same Allpyral mixture and in addition all relevant tree pollens in aqueous extract and a control group received no injections. For determination of antibody titres the radioallergosorbent test (RAST) and the ammonium sulphate precipitation (ASP) technique were used. Cellular responsiveness was studied by measuring birch pollen (BP) induced leucocyte histamine release in peripheral blood. The clinical and immunological response was similar in the two treated groups. Treated patients had less symptoms and a lower consumption of antihistamine tablets during the pollen season than the control group. Non-IgE BP antibodies and IgE antibodies recorded with the ASP technique increased after immunotherapy while RAST values did not change significantly. A decrease of RAST values from postseasonal values during the first year to preseasonal values in the following year was seen in all patient groups but was less pronounced in treated than in untreated patients. The decrease was more pronounced in patients with high RAST values of postseasonal sera than in patients with low RAST values. Cellular reactivity increased slightly during the first phase of therapy but returned to the pre-treatment level later. Clinical improvement was positively correlated to the percentage increase of non-IgE antibody titre and to the pre-treatment non-IgE/IgE antibody ratio. Patients with high preseasonal RAST titres or high cellular sensitivity tended to have more severe symptoms during the pollen season. It is concluded that a mixture of birch, alder and hazel is sufficient for immunotherapy in spring-term hay fever. It is obvious that changes of a single immunological variable do not account for the therapeutic results in immunotherapy.