Generation of suppressor cells in atopic patients during immunotherapy that modulate IgE synthesis

Immunotherapy throughout the decades: from Noon to now

OBJECTIVE

To review major milestones in the development of subcutaneous allergen immunotherapy in 20-year segments.

DATA SOURCES

Review of the literature available in textbooks and journals.

STUDY SELECTION

Articles and books addressing major achievements in the development of subcutaneous allergy immunotherapy were selected for inclusion in this review.

RESULTS

Immunotherapy administration has improved the lives of possibly millions of patients with hay fever. Asthmatic symptoms have been relieved if not ablated in millions as well. Insect venom hypersensitivity became treatable and highly effective. In the beginning years of immunotherapy, it was clear that immunotherapy worked; in the later years, the mechanisms for this efficacy were discovered. In this case, the therapy preceded its validation. Methods, materials, and safety have vastly improved. Postulated mechanisms explain much but not everything.

CONCLUSIONS

There is still research to be accomplished, improvements to be made, and, of course, patients to be made well.

Tracking antigen-specific T-cells during clinical tolerance induction in humans

Allergen immunotherapy presents an opportunity to define mechanisms of induction of clinical tolerance in humans. Significant progress has been made in our understanding of changes in T cell responses during immunotherapy, but existing work has largely been based on functional T cell assays. HLA-peptide-tetrameric complexes allow the tracking of antigen-specific T-cell populations based on the presence of specific T-cell receptors and when combined with functional assays allow a closer assessment of the potential roles of T-cell anergy and clonotype evolution. We sought to develop tools to facilitate tracking of antigen-specific T-cell populations during wasp-venom immunotherapy in people with wasp-venom allergy. We first defined dominant immunogenic regions within Ves v 5, a constituent of wasp venom that is known to represent a target antigen for T-cells. We next identified HLA-DRB1*1501 restricted epitopes and used HLA class II tetrameric complexes alongside cytokine responses to Ves v 5 to track T-cell responses during immunotherapy. In contrast to previous reports, we show that there was a significant initial induction of IL-4 producing antigen-specific T-cells within the first 3–5 weeks of immunotherapy which was followed by reduction of circulating effector antigen-specific T-cells despite escalation of wasp-venom dosage. However, there was sustained induction of IL-10-producing and FOXP3 positive antigen-specific T cells. We observed that these IL-10 producing cells could share a common precursor with IL-4-producing T cells specific for the same epitope. Clinical tolerance induction in humans is associated with dynamic changes in frequencies of antigen-specific T-cells, with a marked loss of IL-4-producing T-cells and the acquisition of IL-10-producing and FOXP3-positive antigen-specific CD4+ T-cells that can derive from a common shared precursor to pre-treatment effector T-cells. The development of new approaches to track antigen specific T-cell responses during immunotherapy can provide novel insights into mechanisms of tolerance induction in humans and identify new potential treatment targets.

The effect of rush immunotherapy with house dust mite in the production of IL-5 and IFN-gamma from the peripheral blood T cells of asthmatic children

Although the mechanisms are unclear, rush immunotherapy (RIT) may be effective to treat allergic diseases. We investigated the long-term modifications of cellular immunity as a mechanism of RIT. The RIT group, included 15 house dust mite (HDM)-sensitized asthmatic children, received RIT only with Dermatophagoides farinae (Der f) and Dermatophagoides pteronyssinus (Der p), whereas the control group, consisted of 10 HDM-sensitized asthmatic children, did not receive RIT. The asthma symptom scores and the skin reactivities to Der f were measured. The cellular proliferative responses and intracellular interleukin (IL)-5 and interferon (IFN)-gamma productions from peripheral blood T cells were also measured before, 8 weeks and 1 yr after RIT. The symptom scores, skin reactivity to Der f and cellular proliferative responses to Der f were decreased significantly after 8 weeks and maintained until 1 yr of RIT. The IFN-gamma/IL-5 ratio of the CD3+ and CD4+ cells were increased significantly after 8 weeks and maintained until 1 yr of RIT, while there were no changes in the control group. These data indicate that the continuous functional modification from Th2 to Th1 phenotype of the CD4+ T cells are developed after RIT in the asthmatic children sensitized with HDM.

Defining the T cell antigen proteome of wasp venom

BACKGROUND

While modulation of T cell function is believed to be important in the successful acquisition of clinical tolerance during venom immunotherapy, little is known of the role of wasp venom specific T cell antigens.

OBJECTIVE

We sought comprehensively to characterize the T cell proteome for wasp venom to facilitate the future development of T cell-based immunotherapeutic approaches.

METHODS

Using peripheral blood mononuclear cells from wasp venom-allergic individuals and IL-4 ELISPOT analysis, we characterized T cell responses to whole venom and gel filtration/ion exchange-fractionated venom. Reactive fractions were purified and identified using highly sensitive electrospray ion-trap mass spectrometry.

RESULTS

Wasp venom-allergic individuals have detectable whole wasp venom-specific T cells directly ex vivo, which show rapid IL-4 effector function. T cell responses to gel filtration/ion exchange fractionated venom were dominated by responses to phospholipase A(1), hyaluronidase and antigen 5.

CONCLUSION

Although it is likely that there are many T cell antigens within wasp venom, the main responses are to proteins coincident with the known IgE-binding proteins.

Dose dependence and time course of the immunologic response to administration of standardized cat allergen extract

BACKGROUND

The immunologic response to allergen immunotherapy with 3 serial 5-fold doses of cat extract has been studied after approximately 5 weeks of immunotherapy. The highest dose containing 15 mug of Fel d 1 produced the most consistent and favorable response. It is unknown whether the comparative response on reaching a maintenance dose is maintained with long-term maintenance therapy.

OBJECTIVE

The purpose of this investigation was to evaluate the immunologic responses with these 3 serial doses of cat hair and dander extract at baseline, after reaching the maintenance dose (approximately 5 weeks), and after 1 year of maintenance immunotherapy.

METHODS

Twenty-eight patients with cat allergy randomized in a double-blind study were assigned to one of 4 treatment groups: placebo or cat hair and dander extract containing 0.6 mug of Fel d 1, 3 mug of Fel d 1, and 15 mug of Fel d 1 at maintenance. Studies included skin prick tests and late cutaneous reactions with cat hair and dander extract, titrated nasal challenges with the extract, serum cat allergen-specific IgG4 and IgE measurement, and flow cytometric and ELISA analysis of whole blood and intranasal cytokines (TGF-beta, IL-10, IFN-gamma, IL-4, and IL-5).

RESULTS

Twenty-six subjects completed the study. After both 5 weeks and 1 year, significant and dose-dependent differences were seen with total symptom scores on nasal challenge ( P < .0001), with titrated skin prick testing with cat dander extract at 5 weeks ( P = .014) and 1 year ( P < .0001), and with cat-specific IgG4 measurement at 5 weeks ( P = .004) and 1 year ( P = .003). At 1 year, neither flow cytometry of whole blood nor ELISA evaluation of nasal cytokines demonstrated any significant differences among the treatment groups.

CONCLUSION

The response to titrated nasal allergen challenge, titrated skin prick testing, and allergen-specific IgG4 measurement to cat immunotherapy at 5 weeks is predictive of the response at 1 year.

T-cell immunotherapy of allergic disease: the role of CD8+ T cells

PURPOSE OF REVIEW

The scope of this review is to place recent advances in T-cell immunotherapy into an account of our understanding of the potential role of CD8+ T cells in the pathogenesis of allergic disease.

RECENT FINDINGS

Studies over the last year suggest that changes in CD8+ T-cell function may represent key events in successful T-cell immunotherapy. The first human human leukocyte antigen class I allergen epitopes have now been described and will provide further insights into the role of allergen-specific CD8+ T cells.

SUMMARY

The coupling of recent technical advances in the study of antigen-specific T cells with the knowledge of human allergen class I epitopes will promote rapid progress in the field, with potential consequences for the diagnosis, monitoring and immunotherapeutic treatment of affected individuals.

Both allergen-specific CD4 and CD8 Type 2 T cells decreased in asthmatic children with immunotherapy

Allergen-specific immunotherapy (IT) has been used for the treatment of atopic diseases since the turn of this century. The precise working mechanisms, however, remain to be clarified. The aim of this study was to investigate the role of particular subsets of allergen-specific T cells in the non-atopic individuals, untreated asthmatic children and the asthmatic children receiving immunotherapy. We collected peripheral blood from 16 untreated asthmatic children and 17 asthmatic children receiving immunotherapy over one and half years. All the patients were sensitive to mite allergen. Peripheral blood mononuclear cells (PBMC) were isolated and, in vitro, stimulated with crude mite extract to enrich the mite-specific T-cell population. After 14 days, the enriched mite-specific T cells were stimulated with phorbol-12-myristate-13-acetate (PMA) and ionomycin for intracellular detection of cytokines such as IFN-gamma, IL-4 in CD4+ and CD8+ T lymphocytes. The data here demonstrated that the levels of mite-specific IgG4 and IgA increased significantly in asthmatic children after immunotherapy. In addition, both IL-4 expressing CD4+ and CD8+ T cells were significantly lower in asthmatic children after immunotherapy compared with those of before treatment and the normal control (p < 0.05). In contrast, the frequency of IFN-gamma expressing CD4+ and CD8+ T cells did not significantly differ between untreated and SIT-treated groups. All these data suggested that decreased Type 2 CD4+ and CD8+ T cells might be closely correlated with the regulatory mechanisms of immunotherapy.

Molecular aspects of allergy

Atopic diseases such as asthma, rhinitis, eczema and food allergies have increased in most industrialised countries of the world during the last 20 years. The reasons for this increase are not known and different hypotheses have been assessed including increased exposure to sensitising allergens or decreased stimulation of the immune system during critical periods of development. In allergic diseases there is a polarisation of the Th2 response and an increase in the production of type 2 cytokines which are involved in the production of immunoglobulin E and the development of mast cells, basophils and eosinophils leading to inflammation and disease. The effector phase of atopy is initiated by interaction with Fc epsilon RI expressed on effector cells such as mast cells and basophils but also found on an ever increasing list of cells. Binding of a polyvalent allergen to the variable part of IgE leads to a cross-link of the receptor that triggers the cell to release histamine and pharmacological mediators of the symptomatic allergic response. Cross-linking of Fc epsilon RI by autoantibodies against the alpha-chain of the Fc epsilon RI, causing subsequent histamine release is thought to be involved in the pathogenesis of other diseases such as chronic idiopathic urticaria (CIU). To date, most therapeutic strategies are aimed at inhibiting and controlling components of the inflammatory response. Recently, new treatment strategies have emerged that focus on the development of preventive and even curative treatments. The most promising therapeutic approaches are aimed at inhibiting the IgE-Fc epsilon RI interaction with the use of non-anaphylactogenic anti-IgE or anti-Fc epsilon RIalpha autoantibodies. Clinical trials in humans using an humanised anti-IgE antibody showed that this antibody was well tolerated and reduced both symptoms and use of medication in asthma and allergic rhinitis. Thus interruption of the atopic cascade at the level of the IgE-Fc epsilon RI interaction with the use of non-anaphylactogenic antibodies is effective and represents an attractive therapy for the treatment of atopic disease.

Immunotherapy for allergic asthma

Specific allergen immunotherapy is an effective treatment of allergic asthma. Double-blind studies provide proof of benefit, although seasonal or intermittent asthma consistently responds better than perennial asthma. Advantages of immunotherapy compared with most pharmacotherapies include modification of the natural history of allergic disease, reduction of need for chronic medication, and treatment of both upper and lower airway disease simultaneously. Improvements in immunotherapy occurred in the later portion of the twentieth century because of enhanced understanding of immunotherapy's mechanism of action, recognition of the dose effect, and improved quality and consistency of allergen vaccines. Purified inhibitors of specific mediators of the allergic response, products of biotechnology, will probably lead to improvements of immunotherapy of asthma in the twenty-first century. The future of immunotherapy and other immunomodulation of allergic asthma is promising.

Wasp venom immunotherapy induces a shift from IL-4-producing towards interferon-gamma-producing CD4+ and CD8+ T lymphocytes

BACKGROUND

Venom immunotherapy (VIT) has proven to be very effective in hymenoptera venom anaphylaxis. However, the underlying immunoregulatory mechanisms of venom immunotherapy remain poorly understood. Recent studies measured the total amount of cytokine in culture supernatans, suggesting a shift in cytokine production from Th2 to a Th1 cytokine profile during VIT. We wanted to examine the contribution of specific T lymphocyte subpopulations, which is impossible using an extracellular method to determine cytokines in supernatants.

OBJECTIVE

The present study was designed to evaluate the effect of VIT on the percentages of type 1 (IL-2, interferon-gamma (IFN-gamma)) and type 2 (IL-4) CD4+ and CD8+ T lymphocytes of patients with wasp venom anaphylaxis during immunotherapy.

METHODS

Peripheral blood mononuclear cells of 20 individuals with a history of wasp sting anaphylaxis and a positive serum wasp venom specific IgE were isolated and in vitro stimulated with phorbol-12-myristate-13-acetate and ionomycin before VIT, at the end of a 5-day semirush VIT and at 6 months during VIT. Three-colour flow cytometric analysis was used for intracellular cytokine (IL-2, IFN-gamma, IL-4) detection in CD4+ (CD3+CD8-) T lymphocytes and CD8+ (CD3+CD8+) T lymphocytes.

RESULTS

At the end of a 5-day semirush VIT, there was a significant decrease in percentage of IL-4-producing CD4+ and CD8+ T cells, compared with cytokine-producing cells before VIT (P = 0.0002 and 0.004). After 6 months of VIT, patients showed an increased number of IL-2-producing stimulated CD4+ and CD8+ lymphocytes compared with values before VIT (P = 0.002 and P = 0.0003). A higher amount of IFN-gamma-producing stimulated CD4+ and CD8+ cells was found after 6 months of VIT (P = 0.001 and P = 0.0006). There was no correlation between cytokine-producing cells and specific IgE for wasp.

CONCLUSION

Venom immunotherapy induced a shift from IL-4-producing towards IFN-gamma-producing CD4+ as well as CD8+ T lymphocytes.

Immunologic changes associated with allergen immunotherapy

Specific allergen injection immunotherapy is highly effective in selected patients with IgE-mediated disease, including respiratory allergy and venom anaphylaxis. Research in this area provides insight into the immunologic basis of allergic disease and may assist in the development of more highly targeted treatment. Immunotherapy reduces immediate allergen-induced symptoms and concentrations of inflammatory mediators, including histamine and prostaglandin D2, in ragweed-sensitive patients. Similarly, nasal epithelial mast cell numbers are decreased. A characteristic feature of immunotherapy is its ability to inhibit late-phase responses. In the nose it is accompanied by a decrease in eosinophil numbers in lavage during late responses. Characteristic changes in serum immunoglobulins are found, with an initial increase in IgE followed by a blunting of seasonal increases in IgE in pollen-sensitive patients and a gradual decline in allergen-specific IgE levels over several years. This is accompanied by an increase in allergen-specific IgG (blocking antibodies), although neither appear to correlate closely with the clinical response to immunotherapy. One way in which immunotherapy may act is by modifying the T-lymphocyte response to subsequent natural allergen exposure. Studies in peripheral blood and within the target organ have demonstrated a shift in the balance of T-cell subsets away from TH2-type (producing particularly IL-4 and IL-5) in favor of a TH1-type T-lymphocyte response (with the preferential production of IFN-gamma). Studies of the nasal mucosa before and after immunotherapy have demonstrated suppression of the late nasal response and increases in the numbers of cells expressing mRNA for IFN-gamma. It is not clear whether this immune deviation is due to anergy of TH2/TH0 cells or increases in TH0/TH1 T-lymphocyte responses. An alternative may be amplification of suppressor CD8+ T cells, which may have a downregulatory effect. Novel approaches currently being explored include the use of T-cell reactive peptides, which might circumvent the risk of anaphylaxis, and the use of adjuvants such as IL-12 or mycobacterial vaccines to potentiate the effects of allergen in inducing immune deviation.

Immunologic changes during immunotherapy in asthmatic children: increased IL-13 and allergen-specific IgG4 antibody levels

BACKGROUND

The prevalence of allergic diseases such as asthma, allergic rhinitis, and atopic diseases has increased in recent years. Immunotherapy with allergens is a treatment documented to have an effect on regulating cytokine production and allergen-specific antibody production.

OBJECTIVE

The aim of this study was to further investigate immunologic changes during immunotherapy and to explore the possible more efficient approach of immunotherapy.

METHODS

Asthmatic children receiving house dust mite immunotherapy were followed to learn immunologic parameters such as allergen-specific antibody levels, proliferative response of peripheral blood mononuclear cells, and cytokine change during immunotherapy.

RESULTS

The data suggested (1) IgG4 anti-mite antibody increased 8 months after immunotherapy while IgE antibody level remained the same; (2) allergen-induced, in vitro production of certain cytokines such as IL-4 and IL-10 decreased after immunotherapy; (3) IL-13 (which can induce IgG4 and IgE antibody production by B cells) increased after immunotherapy.

CONCLUSION

Although this needs more study, IL-13 might play an important role in the generation of IgG4-blocking antibody during immunotherapy.

Mediator release is altered in immunotherapy-treated patients: a 4-year study

In recent years, it has been possible to demonstrate mediator release into the nasal secretion after nasal allergen challenge in patients with allergic rhinitis. Using the nasal provocation model, we determined whether the mediator release was altered in immunotherapy-treated patients. Seventeen grass-pollen-allergic patients were examined under controlled, reproducible conditions. Serial challenges with increasing doses of grass pollen produced increasing numbers of clinical symptoms and release of mediators such as kinins, TAME-esterase activity, and histamine. Ten patients received a semidepot perennial grass-pollen extract for 4 years. Seven patients served as controls and did not receive immunotherapy during the observation period. Data from the group of patients receiving immunotherapy over the first year already showed a partially significant decline in the maximal mediator release after nasal allergen challenges compared to the results of pretreated challenges, whereas controls did not show any significant changes. Nasal allergen challenges after termination of 4 years' immunotherapy significantly modified the mediator release compared to pretreatment values (TAME-esterase activity P < 0.05, kinins P < 0.01, and histamine P < 0.01). Decrease of mediator release paralleled the symptom-medication scores and quantitative skin prick test. Finally, we could demonstrate a significant correlation between specific IgG increase and mediator decrease in the treated group.

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.

Venom immunotherapy modulates interleukin-4 and interferon-gamma messenger RNA expression of peripheral T lymphocytes

The mechanism by which specific immunotherapy exerts its beneficial effect remains unclear. In order to evaluate the influence of venom immunotherapy on the T-cell cytokine pattern of allergic reactions, we studied interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) mRNA expression of peripheral T lymphocytes from 12 patients undergoing rush venom desensitization, before treatment at Day 0 (D0), at Day 15 (D15) and Day 90 (D90) after treatment, and from seven controls. Antigen-specific T-cell proliferation was also determined. Cytokine mRNA expression was evaluated using in situ hybridization, 24 hr after culture of peripheral T cells with medium, venom, or an unrelated allergen. Allergen-induced T-cell proliferation decreased at D15 and D90 of rush immunotherapy (P < or = 0.02). In venom-stimulated cultures of the patient group, there was a decrease in IL-4 mRNA-positive cells at D15 and D90 (P < or = 0.001). Before desensitization, IFN-gamma mRNA expression was lower in patients than in controls and did not increase after in vitro allergen stimulation. In contrast, after immunotherapy, spontaneous IFN-gamma mRNA expression increased, but only at D90 (P < or = 0.001). The cytokine pattern observed at D90 after immunotherapy was similar to that observed in control subjects. In conclusion, venom immunotherapy induced an altered cytokine mRNA pattern in allergen-stimulated T cells which was dissociated from the early changes of allergen-induced T-cell responsiveness.

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.

Influence of hyposensitization on soluble interleukin-2 receptor, eosinophil cationic protein, in vitro lymphocyte proliferation, in vitro lymphocyte adhesion, and lymphocyte membrane markers in childhood asthma

Soluble interleukin-2 receptor (sIL-2R), eosinophil cationic protein (ECP), the lymphoproliferative response to house-dust mite (HDM), adhesion to human umbilical vein endothelial cells (HUVEC), and lymphocyte membrane markers were studied in three groups of children: healthy children, asthmatic children without hyposensitization (HS), and asthmatic children with HS. HS was associated with significantly lower numbers of peripheral blood eosinophils (PBE) and lower sIL-2R serum levels and with a tendency to lower ECP serum levels and lymphoproliferative response to HDM. There were no changes in the T-lymphocyte phenotypic markers CD4 and CD8 among the three groups. The interleukin-2 receptor (IL-2R, CD25) on HDM-stimulated T lymphocytes increased over unstimulated T lymphocytes in the three groups. The CD25 expression was higher on HDM-stimulated lymphocytes in both asthmatic groups than in healthy children. Adhesion of lymphocytes on HUVEC increased significantly after HDM stimulation in asthmatic children without HS, whereas no change was observed in the two other groups. However, there was no change in the expression of adhesion molecules CD29 and CD11a on lymphocytes in either of the groups. This study provides further evidence that HS can modify lymphocyte and eosinophil functions.

Lymphocyte infiltration and thickness of the nasal mucous membrane in perennial and seasonal allergic rhinitis

We have used immunocytochemical techniques to study infiltration by lymphocytes in biopsy specimens of the nasal mucosal membrane in 24 atopic patients and 10 normal volunteers. Twelve patients had perennial rhinitis and 12 had seasonal allergic rhinitis (SR) to grass pollen. Biopsy specimens were taken both in and out of the pollen season in patients with SR. Biopsy specimens were strained with the indirect immunoperoxidase technique and monoclonal antibodies to CD3, CD4, CD8, CD22, and CD25. T helper cells (CD4+) and CD24+ cells were significantly more numerous in patients exposed to allergen (those with perennial rhinitis and SR in season) compared with normal volunteers, whereas values for SR out of season were intermediate. The thickness of the nasal epithelium was significantly (p < 0.05) greater in biopsy specimens from patients with perennial rhinitis (mean, 51.43 microns) than in those from patients with SR in season (median, 32.44 microns). These results suggest that in allergic rhinitis, natural exposure to allergen is accompanied by increased infiltration of the nasal mucous membrane by T-helper and CD25+ cells.

The effect of immunotherapy on T-cell subsets in peripheral blood and bronchoalveolar lavage fluid in pollen-allergic patients

The effect of immunotherapy (IT) on T-cell subsets in peripheral blood and bronchoalveolar lavage fluid (BAL) was examined in 15 patients with rhinoconjunctivitis and asthma caused by sensitivity to birch pollen. They were treated with IT for 3 years. Seven patients were treated with highly standardized birch-pollen extract (Pharmacia, Sweden). Eight untreated patients served as controls. Histamine challenge, blood sampling, and BAL were performed before (January, February), and at the peak of, the birch-pollen season (May). The subpopulations of T cells in peripheral blood and BAL fluid were investigated by immunocytochemistry and flow cytometry. During the birch-pollen season, the percentage of CD3+ and CD4+ cells of blood mononuclear cells in the IT patients increased significantly (P < 0.03 and P < 0.02, respectively). The percentage of CD8+ cells remained unaltered. In control patients, no changes of T-cell subsets in the peripheral blood were observed. T-cell subsets in BAL did not change during the season in relation to preseasonal values for either IT-treated or non-IT-treated patients.

Lymphocyte transformation test with house dust mite (Dermatophagoides pteronyssinus) in normal children, asthmatic children and asthmatic children receiving hyposensitization

In the first part of this study the proliferative response of lymphocytes (lymphocyte transformation test) to house dust mite (HDM) stimulation in cultures was studied in normal children (n = 16), asthmatic children who never received hyposensitization (HS) (n = 50) and asthmatic children receiving HS with HDM for at least 6 months (n = 20). The results are expressed as disintegrations per minute (d.p.m.) and as stimulation index (SI = d.p.m. in the presence of the allergen/d.p.m. in the control culture). A positive SI (> 2) was found in 54% of the asthmatic children who never received HS, in 30% of the asthmatics receiving HS and in none of the normal children. Furthermore, between asthmatics with and without HS, the SI was not statistically different, although asthmatics without HS tended to have a higher SI (median value: 2.13 vs 1.38) (P = 0.10). In a second series of experiments the effect of adding interleukin-2 (IL-2) to the lymphocyte cell culture was studied in asthmatic children with and without HS. Interleukin-2 induced an additional stimulatory effect on the lymphoproliferative response to HDM and to phytohaemagglutinin in patients who never received HS, but had no effect in patients receiving HS. We conclude that HS treatment seems to have an inhibiting effect upon this proliferative response, not only inhibiting the degree of the allergen-induced lymphocyte proliferation, but also inhibiting the sensitivity of proliferating lymphocytes for IL-2. These inhibiting effects upon lymphocytic activation could be responsible for the anti-inflammatory effects (i.e. suppression of the late asthmatic reaction) of HS.

Efficacy of liposome entrapped allergen in down regulation of IgE response in mice

The effect of liposome entrapped allergen on primary, secondary and ongoing IgE response was studied in mice. It was observed that mice primed with liposome entrapped allergen maintained significantly lower levels of serum specific IgE as compared to that of controls primed with allergen. Although alum adsorbed allergen could induce IgE synthesis in mice primed with liposome entrapped allergen the increase in serum specific IgE levels was lower than the animals primed and challenged with alum adsorbed allergen. On the contrary when BALB/c mice were primed with alum adsorbed allergen to induce IgE synthesis subsequent challenge by liposome entrapped allergen could down regulate the serum specific IgE response. Serum specific IgG response did not show any significant difference between the two groups. There was an increase in T suppressor cell subpopulation as measured by immunofluorescence technique in mice injected liposome entrapped allergen as compared to that in controls. The results indicate that liposome entrapped allergens may prove to be safe and effective in immunotherapy by reducing the allergenic response of the allergen at the same time increasing the antigenicity.

The effect of immunotherapy on interleukin-1 and tumor necrosis factor production of monocytes in asthmatic children

A longitudinal study was conducted to determine the pathogenesis and effect of immunotherapy (IT) on monocyte function. Production of interleukin-1 (IL-1) and tumor necrosis factor (TNF) by peripheral blood monocytes in 31 asthmatic children before and one year after IT was compared. Twenty-two children completed the treatment course, and 13 age-matched healthy children served as controls. Adherent monocytes were isolated and stimulated with either crude mite extract of Dermatophagoid farinae (Df) for 7 days or lipopolysaccharide (LPS) for 3 days. The amount of TNF and IL-1 in culture supernatant was quantified by TNF and IL-1 enzyme-linked immunosorbent assay (ELISA) kits, respectively. The LPS-stimulated TNF production in patients was not different before or after IT (245.8 +/- 110.9 vs. 213.3 +/- 161.6 pg/0.1 ml, p +/- 0.202), but was significantly higher than the control (66.7 +/- 42.7 pg/0.1 ml; p less than 0.0001). The LPS-stimulated IL-1 production was similar among the three groups. When stimulated with Df antigen, monocytes from asthmatic patients produced a greater amount of TNF and IL-1 than did those from the control (p less than 0.001). Furthermore, although the production of TNF decreased after successful IT (360.2 +/- 181.6 vs 243.9 +/- 189.1 pg/0.1 ml, p less than 0.05), the production of IL-1 did not change (679.9 +/- 254.1 vs. 534.8 +/- 257.6 pg/0.1 ml, p greater than 0.05). Thus, repeated long-term administration of allergen (IT) was able to suppress specifically the TNF, but not IL-1 production of monocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Correlation between conjunctival provocation test (CPT) and systemic allergometric tests in allergic conjunctivitis

In order to assess the potential usefulness of CPT as a diagnostic tool for ocular allergy, the correlation between skin/RAST tests and CPT was determined in 144 patients affected by allergic 'hay fever' type conjunctivitis. The results showed that an agreement between skin/RAST tests and CPT occurred in 71% of the cases (130/183). Of the 29% uncorrelated cases, 23% (43/183) were positive for at least one specific antigen by skin/RAST tests but not by CPT, while 6% (10/183) were positive for at least one specific antigen by CPT, but not by skin/RAST tests. CPT dramatically increased the histamine levels in tears (p less than 0.001). These findings show that (1) systemic tests can be misleading in that they may suggest a specific sensitisation which, in fact, does not involve the conjunctiva (systemic test positive/CPT negative); (2) CPT can identify local conjunctival sensitisation in the absence of a systemic sensitisation (systemic test negative/CPT positive); (3) CPT can demonstrate that allergic 'hay fever' type conjunctivitis may be related to allergens different from those responsible for a systemic sensitisation.

Evaluation of immunotherapy-induced changes in specific IgE, IgG and IgG subclasses in birch pollen allergic patients by means of immunoblotting. Correlation with clinical response

Sera from 27 birch pollen-allergic patients who had undergone hyposensitization treatment for 22-41 months were studied by immunoblotting before and after therapy, whereby the levels of IgE, IgG and IgG1-4 antibodies directed against the major allergen Bet v I and minor allergens of birch pollen were monitored. The clinical benefit of immunotherapy (IT) was evaluated using a symptom specific questionnaire. In patients with good clinical response (responders, n = 18), as defined by improvement of symptoms, anti-Bet v I IgE antibodies were found to decrease in 10/18 patients (55.5%), whereas in 6/18 (33.3%) no change and in two cases (11.2%) an increase of specific IgE was observed. In the group of patients with unsatisfactory clinical outcome (non-responders, n = 9), 3/9 patients (33.3%) showed a decrease, 3/9 (33.3%) no change and 3/9 (33.3%) an increase in levels of IgE antibodies directed against Bet v I. In the case of minor allergens, 5/18 responders (27.7%) and 8/9 non-responders (88.8%) showed specific IgE before IT. In the responder group, no increase of specific IgE could be observed after IT. In non-responders, however, an increase of IgE directed against minor allergens was seen in 3/9 patients (33.3%). In all patients, regardless of therapeutical success, IT-induced elevated levels of specific IgG, IgG1 and in particular IgG4 directed against Bet v I were found. Regarding minor allergens, a heterogeneous pattern of IgG responses without significant correlation to clinical benefit was observed. Our results indicate that changes in IgG reactivity patterns against Bet v I and minor allergens, as shown by the immunoblot technique, did not correlate with good or bad clinical outcome.

Lymphocyte-mediated inhibition of platelet cytotoxic functions during Hymenoptera venom desensitization: characterization of a suppressive lymphokine

Recently, it has been shown that platelets, through a receptor for the Fc fragment of IgE, could be specially triggered by venom allergens in hypersensitivity to hymenoptera, generating cytocidal mediators toward Schistosoma mansoni larvae, and oxygen metabolites measured by chemiluminescence. After rush immunotherapy, a depressed platelet response was demonstrated to be associated with the production of lymphokine(s). Here we report the characterization of a factor present in supernatants of antigen-stimulated T cells from patients after hymenoptera venom desensitization which is able to inhibit platelet cytotoxic functions in a dose-dependent manner. The optimal inhibition was observed with supernatants obtained after T lymphocyte stimulated with 10(-5) micrograms venom allergen/ml. Once specifically produced the platelet-suppressive effect of lymphocyte supernatants was not antigen specific. The producing T cell subpopulation was identified as CD8+. This lymphokine had an approximate molecular mass of 25 kDa and a pI of 4.8. It was heat and acid stable and sensitive to trypsin and proteinase K but not to neuraminidase. This platelet inhibitory activity was absorbed by platelet membrane suggesting its binding to a receptor. These properties were very similar to a previously described platelet activity suppressive lymphokine, suggesting the participation of this lymphokine in the mechanisms of rush desensitization.

Detection of auto-anti-idiotypic antibodies to Lol p I (rye I) IgE antibodies in human sera by the use of murine idiotypes: levels in atopic and non-atopic subjects and effects of immunotherapy

Anti-idiotypic antibodies (anti-Id Abs) are involved in the regulation of a number of immune responses including the IgE antibody production. In atopic patients, the increased synthesis of IgE antibodies could be related to a defective production of regulatory anti-Id Abs. In the present study, we first developed a sensitive assay for measuring the levels of anti-Id Abs directed against antibodies specific for Lol p I, the major allergenic determinant of Lolium perenne (rye grass). In this assay, we used previously described murine monoclonal anti-Lol p I antibodies that were shown to share epitopic specificities with human anti-Lol p I IgE and IgG antibodies, thus short-cutting the need for purification of F(ab')2 fragments of human IgG Abs and insuring optimal specificity and sensitivity. Levels of anti-Id Abs against two anti-Lol p I monoclonal antibodies (290A-167, 348A-6) were higher in normal volunteers than in untreated atopic patients. Specific immunotherapy increased the levels of anti-Id Abs to those of normal volunteers. These observations suggest a role for the Id-anti-Id network in the regulation of IgE antibody production.

Lymphocyte activation by house dust allergen in asthma: analysis with monoclonal antibodies

Peripheral blood mononuclear cell (MNC) response to house dust (HD) stimulation in cultures was studied in a group of 35 subjects with asthma and a multiple positive skin test (ST) reaction to inhalant allergens including HD, and in 19 healthy controls. The MNC response to allergen stimulation was assessed by interleukin-2 receptor (IL-2R) expression identified with an anti-Tac monoclonal antibody. Lymphocyte subpopulations of baseline and cultured cells were also analysed. The percentage of IL-2R presenting cells increased significantly in HD-driven cultures in the asthma group compared to controls. The increase in proportion of IL-2R+ cells was closely related to the increase in CD4+ percentage of cultured cells and was accompanied by a decrease in proportion of CD8+ lymphocytes and monocytes/macrophages, suggesting that HD-activated cells were CD4+ lymphocytes. Lymphocyte activation, measured by IL-2R expression, was significantly higher in the group of asthmatics, and positive dual (early and late) skin reaction to HD, as compared to those with single early reaction.

Immune mechanisms in allergen-specific immunotherapy

Allergen-specific immunotherapy has been shown to be clinically effective in patients with seasonal allergic rhinitis and/or asthma. Patients who receive this therapy undergo a number of specific immunologic changes in response to the allergen being administered. These include a "blunting" of the seasonal rise of allergen-specific IgE as well as lowering baseline IgE levels, generation of an allergen-specific IgG response, development of auto-anti-idiotypic antibodies, reduced basophil histamine release in response to allergen, decreased lymphocyte proliferation, lymphokine production in response to allergen, and the generation of allergen-specific suppressor T cells that down-regulate lymphoproliferative responses and IgE synthesis. The mechanism by which allergen-specific immunotherapy produces clinical efficacy is not known. Recent evidence suggests that the development of immunoregulatory responses (suppressor T cells and anti-idiotypic antibodies) during immunotherapy may account for the immunologic changes described above but as yet have not been correlated with clinical outcome. Identification of epitopes on allergens that can induce selective T helper/suppressor responses may provide opportunities for producing immunological tolerance and a reduction in the allergic diathesis.

Responses to ragweed-pollen nasal challenge before and after immunotherapy

To evaluate whether immunotherapy reduces mediator release after nasal challenge, we followed previously untreated patients with ragweed hay fever through 2 years (three seasons) of treatment. Eleven adult patients started immunotherapy after a season of symptom diaries and graded pretreatment challenges with 0.03, 0.3, 3.3, and 16.5 mg of ragweed pollen. Repeat challenges were performed when the treatment dosage reached 0.6, 12.4, and 24.8 micrograms of Amb a I (antigen E) equivalents per injection. After the 0.6 micrograms dose, there was little change, but after the larger doses, there was a significant reduction in histamine and tosylarginine methyl ester-esterase (TAME-esterase) release in two respects. More pollen was required before any mediator appeared, and the amount of mediator released at each stage of the challenge was reduced. There was no significant difference between the responses at the 12.4 and 24.8 micrograms treatment doses. Sneezing after challenge was not apparently changed after immunotherapy; however, patients' seasonal symptom-medication scores were reduced after treatment. These data set the optimal individual treatment dose of ragweed extract for immunotherapy at greater than 0.6 micrograms, but probably not more than 12.4 micrograms in terms of Amb a I equivalents.

Maxisorp RAST. A sensitive method for detection of antigen-specific human IgE in culture fluids

For determination of allergen-specific IgE in cell culture supernatants and other highly diluted IgE preparations a radioallergosorbent test (RAST) based on high adsorption polystyrene test tubes has been developed ("Maxisorp RAST"). Cladosporium herbarum extract was used as a model allergen but timothy grass pollen, house dust mite and dog dander showed similar results. The test showed specificities of both allergen and immunoglobulin isotype and significant correlations (r = 0.67-0.88) with established RAST procedures were found. Based on immunosorbent-purified allergen-specific IgE the estimated sensitivity was within the order of 150-300 pg allergen-specific IgE per ml. The within-assay variation was 4-9% and the inter-assay-variation 17-29%. The Maxisorp RAST is useful as an inhibition assay for quantitating allergenic activity down to 0.1 biological units/ml of allergen extracts.

Hymenoptera venom immunotherapy. II. T proliferative and T suppressive activities induced by Vespula immunotherapy: effects on long-term antibody responses

Thirty-five children who had exhibited major clinical reactions to yellow jacket stings were desensitized during an 8-day rush immunotherapy (RIT). Maintenance treatment was continued for at least 1 year in all cases and for 2 years in 21 cases. Blood samples, obtained before, during, and after RIT, were analyzed for specific T proliferative (TP) and T suppressive (TS) cell activities and for specific IgE, IgG1, and IgG4 levels. TS and TP cell activities increased during RIT (p less than 0.001) and remained elevated throughout the 2-year follow-up. There were transient rises in specific IgG1 and IgE during RIT, but the levels of both decreased thereafter. Specific IgG4 increased throughout the follow-up period. The data indicate that the levels of specific IgE and specific IgG1 were correlated with TP cell responses (inducers) and TS cells responses (suppressors) and therefore might be controlled by them; data also suggest that TS cell responses should play a role in the IgG4 response. These changes in TS and TP cell responses and antibody responses have been incorporated into a model of antibody-response regulation by cell-mediated immunity in this type of allergy.

Decreased production of CD8 (T8) antigen after immunotherapy

The working mechanism(s) of immunotherapy still remains ill defined. As T cells bearing CD8 antigen possess suppressor/cytotoxic function, this study was conducted to examine the effect of immunotherapy on the production of CD8 antigen. Peripheral blood mononuclear cells (MNC) were obtained from 21 newly diagnosed and 23 hyposensitized (greater than 1 year) asthmatic children and 13 age-matched normal children. MNC were stimulated with crude mite extract (Dermatophagoides farinae) for 7 days and with phytohemagglutinin and concanavalin A for 3 days. The CD8 antigen and interleukin-2 receptor (IL-2R) in plasmas and culture supernatants were measured by CELLFREE T8 and IL-2R test kits (T Cell Sciences, USA). The results showed the following. (1) Plasma CD8 antigen was markedly increased in new patients compared to normals (536.7 +/- 212.3 vs 222.5 +/- 104.0 units/ml; P less than 0.001) and decreased to normal after immunotherapy (275.7 +/- 98.5 units/ml). (2) When stimulated with mite allergen, MNC from both new and hyposensitized patients produced a much greater amount of CD8 antigen compared to those from normals. However, after immunotherapy MNC tended to produce less CD8 antigen, although not to a significant degree. (3) No difference in CD8 antigen production was seen among three groups when lymphocytes were stimulated with mitogens. (4) Production of CD8 antigen paralleled that of IL-2R. Thus, CD8 production was specifically decreased after immunotherapy and this fact reflects a hyposensitized state of T cells after long-term, repeated injection of allergens.

Hymenoptera venom immunotherapy. I. Induction of T cell-mediated immunity by honeybee venom immunotherapy: relationships with specific antibody responses

The specific cell-mediated and humoral immune responses of 14 children allergic to honeybee venom were studied. An 8-day rush venom immunotherapy induced an increase in T proliferative (p less than 0.04) and T suppressive (p less than 0.003) cell-specific activities. Antibody variations, an increase in specific IgG4 (p not equal to 0.05), and a decrease in specific IgE (p less than 0.01) were observed 1 year later. Initial high T suppressive cell activity prevents T proliferative cell increase during rush venom immunotherapy. High initial levels of specific IgG1 and specific IgG4 have opposing effects on the increase in T suppressive cell activity, the former being positively correlated with intensive increase (r = 0.840; p less than 0.005), the latter negatively with T suppressive cell increase (r = -0.709; p less than 0.001). These data indicate that there are interrelationships between the cell-mediated immunity and the antibody responses in honeybee allergy.

T cell responses in allergic rhinitis, asthma and atopic dermatitis

Although clinical responses to allergens have been shown to primarily involve IgE antibodies, there is often no clear correlation between the amount of allergen-specific IgE present in the serum and the nature and severity of allergic symptoms. This observation raises the question of the possible role of non-IgE mediated types of immune responses in this reaction. It is not known to what extent components of T cell-mediated immunity are involved in IgE-mediated reactions but several observations suggest an association between atopic disease and alterations in cellular immune function. These include the frequent association of high serum IgE levels with: (i) several of the primary and acquired immunodeficiencies characterized by partial T cell deficiency; (ii) the defective cell-mediated immunity and resultant recurrent infections seen in the hyper-IgE syndrome; and (iii) the sudden rise in serum IgE levels associated with reduced numbers of suppressor T cells in bone marrow transplant recipients during the acute graft vs host disease. In this review, we will examine the recent evidence suggesting that the T lymphocyte may play a primary role in the pathogenesis of atopic disorders.

Allergic rhinitis: recent advances

Our understanding of the pathophysiology of allergic rhinitis is increasing as a result of the development of new research tools for investigation of patients with this disorder. The pharmacologic treatment of allergic rhinitis has been greatly improved by introduction of relatively nonsedating H1-receptor antagonists and potent, topically active, glucocorticosteroids. Immunotherapy for allergic rhinitis is also changing with the times. Patient selection criteria are becoming more strict, and the introduction of safer, modified allergens with decreased allergenicity and retained immunogenicity will be a major advance.