Allergic rhinitis to ragweed pollen. II. Modulation of histamine-releasing factor production by specific immunotherapy

Inhibitors of dimerized translationally controlled tumor protein, a histamine releasing factor, may serve as anti-allergic drug candidates

It has been established that translationally controlled tumor protein (TCTP), also called histamine releasing factor (HRF), exhibits cytokine-like activities associated with initiation of allergic responses only after forming dimers (dTCTP). Agents that inhibit dTCTP by preventing its dimerization or otherwise block its function, also block development of allergic reactions, thereby serving as potential drugs to treat allergic diseases. Several lines of evidence have proven that peptides and antibodies that specifically inhibit the interactions between dTCTP and either its putative receptor or immunoglobulins exhibit significant in vivo efficacy as potential anti-inflammatory agents in murine models of allergic inflammatory diseases. This review highlights the development of several inhibitors targeting dTCTP and discusses how they affect the pathophysiologic processes of allergic and inflammatory diseases in several animal models and offers new perspectives on anti-allergic drug discovery.

History of Histamine-Releasing Factor (HRF)/Translationally Controlled Tumor Protein (TCTP) Including a Potential Therapeutic Target in Asthma and Allergy

Histamine-releasing factor (HRF) also known as translationally controlled tumor protein (TCTP) is a highly conserved, ubiquitous protein that has both intracellular and extracellular functions. Here we will highlight the subcloning of the molecule, its clinical implications, as well as an inducible-transgenic mouse. Particular attention will be paid to its extracellular functioning and its potential role as a therapeutic target in asthma and allergy. The cells and the cytokines that are produced when stimulated or primed by HRF/TCTP will be detailed as well as the downstream signaling pathway that HRF/TCTP elicits. While it was originally thought that HRF/TCTP interacted with IgE, the finding that cells not binding IgE also respond to HRF/TCTP called this interaction into question. HRF/TCTP or at least its mouse counterpart appears to interact with some, but not all IgE and IgG molecules. HRF/TCTP has been shown to activate multiple human cells including basophils, eosinophils, T cells, and B cells. Since many of the cells that are activated by HRF/TCTP participate in the allergic response, the extracellular functions of HRF/TCTP could exacerbate the allergic, inflammatory cascade. Particularly exciting is that small molecule agonists of the phosphatase SHIP-1 have been shown to modulate the P13 kinase/AKT pathway and may control inflammatory disorders. This review discusses this possibility in light of HRF/TCTP.

Histamine-releasing factor: a promising therapeutic target for food allergy

The prevalence of food allergies has been increasing at an alarming rate over the last few decades. Despite the dramatic increase in disease prevalence, the development of effective therapies has not kept pace. In this issue of the JCI, Ando et al. provide a causal link between histamine-releasing factor (HRF) interactions with IgE and food allergy in a murine model. Successful oral immunotherapy of both egg-allergic human patients and food-allergic mice was associated with sustained suppression of HRF-reactive IgE levels. These results support a role for HRF-IgE interactions in the amplification of intestinal inflammation and suggest HRF as a therapeutic target in food allergy.

Potential role of histamine releasing factor (HRF) as a therapeutic target for treating asthma and allergy

Histamine releasing factor (HRF), also known as translationally controlled tumor protein (TCTP), is a highly conserved, ubiquitous protein that has both intracellular and extracellular functions. Here, we will highlight the history of the molecule, its clinical implications with a focus on its extracellular functioning, and its potential role as a therapeutic target in asthma and allergy. The cells and cytokines produced when stimulated or primed by HRF/TCTP are detailed as well as the downstream signaling pathway that HRF/TCTP elicits. While it was originally thought that HRF/TCTP interacted with IgE, the finding that cells not binding IgE also respond to HRF/TCTP called this interaction into question. HRF/TCTP, or at least its mouse counterpart, appears to interact with some, but not all IgE and IgG molecules. HRF/TCTP has been shown to activate multiple human cells including basophils, eosinophils, T cells, and B cells. Since many of the cells activated by HRF/TCTP participate in the allergic response, extracellular functions of HRF/TCTP may exacerbate the allergic, inflammatory cascade. Particularly exciting is that small molecule agonists of Src homology 2-containing inositol phosphatase-1 have been shown to modulate the phosphoinositide 3-kinase/AKT pathway and may control inflammatory disorders. This review discusses this possibility in light of HRF/TCTP.

Mechanisms of immunotherapy: a historical perspective

OBJECTIVE

To provide a historical review of mechanisms proposed during the last century to explain the efficacy of immunotherapy.

DATA SOURCES

We retrieved review articles and original research from MEDLINE, OVID, and PubMed that addressed our topic of interest.

STUDY SELECTION

Articles were selected for their relevance to immunotherapy and mechanisms.

RESULTS

Early studies focused on the production of blocking antibodies induced by immunotherapy, with mechanistic explanations aimed at understanding a relationship between blocking antibodies and clinical response. This was followed by a period when the effects of immunotherapy on levels and function of effector cells in the allergic response were studied. Aiding in characterization of this response was the discovery of IgE and its role in allergic sensitization, which brought a renewed focus on the antibody-mediated effects of immunotherapy. In an attempt to create a unifying hypothesis to explain humoral and cellular mechanisms of immunotherapy, recent approaches have been focused on the role of the T cell and, specifically, regulatory T cells.

CONCLUSIONS

Although the clinical practice of immunotherapy has been refined since its introduction 100 years ago, our understanding of the mechanisms that underlie this success has awaited discoveries in basic immunology.

A review of allergen-specific immunotherapy in human and veterinary medicine

This article reviews allergen-specific immunotherapy in human and veterinary medicine. Current hypotheses of possible mechanisms of actions are outlined. Indications, success rates, adverse effects and factors influencing outcome of therapy are discussed in humans, dogs, cats and horses.

Differential diagnoses of conjunctivitis for clinical allergist-immunologists

OBJECTIVE

To provide a clinical overview of the types of conjunctivitis that are encountered by practicing clinical allergist-immunologists.

DATA SOURCES

Published literature in peer reviewed journals found in the National Library of Medicine (PubMed) database using the keywords ocular allergy and/or allergic conjunctivitis.

STUDY SELECTION

Studies related to ocular allergy and/or allergic conjunctivitis were selected for inclusion in this review.

RESULTS

Four clinical scenarios are presented that mimic frequently encountered inflammatory disorders that present as red eyes.

CONCLUSIONS

The signs and symptoms associated with the various inflammatory conditions affecting the conjunctiva often overlap and need to be differentiated to maximize care for patients with conjunctivitis.

Allergen injection immunotherapy for seasonal allergic rhinitis

BACKGROUND

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

OBJECTIVES

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

SEARCH STRATEGY

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Is outdoor air pollution associated with physician visits for allergic rhinitis among the elderly in Toronto, Canada?

BACKGROUND

While a number of studies suggest that air pollution is associated with allergic rhinitis in children, findings among adults have been equivocal. The aim of this study was to examine the relationship between outdoor air pollution and physician visits for allergic rhinitis among individuals>or=65 years of age in Toronto, Canada.

METHODS

Physician visits were identified by using data from the Ontario provincial health insurance plan that is made available to all residents. Our analyses are based on 52,691 physician visits for allergic rhinitis among individuals>or=65 years of age in the Toronto metropolitan area between 1995 and 2000. Generalized linear models were used to regress daily counts of physician visits against daily measures of gaseous and particulate components of air pollution after controlling for seasonality, potential confounders (temperature, relative humidity, aeroallergens), overdispersion and serial correlation.

RESULTS

A large number of comparisons were undertaken, with most showing no statistically significant associations between daily levels of air pollution and the number of physician visits for rhinitis. In contrast, an interquartile increase in the 10-day average of ragweed particles increased the mean number of daily rhinitis consultations by 6.4% (95% CI=0.7-12.4%).

CONCLUSIONS

Our findings suggest that outdoor air pollution is a poor predictor of physician visits for allergic rhinitis among the elderly.

Effectiveness of specific immunotherapy in the treatment of allergic rhinitis: an analysis of randomized, prospective, single- or double-blind, placebo-controlled studies

BACKGROUND

The effectiveness of specific immunotherapy (SIT) in the treatment of allergic rhinitis has been supported by empirical evidence and clinical experience.

OBJECTIVE

This report is an analysis of multiple studies involving patients with documented allergic rhinitis.

METHODS

All studies of the effectiveness of SIT in the treatment of allergic rhinitis published in English between the years 1966 and 1996 were identified through a MEDLINE search. All prospective, single- or double-blind, placebo-controlled studies were included in the analysis. One author (R.N.R.) extracted data from the studies. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random-effects model for a variety of clinical measures in studies that permitted the extraction of numbers of patients with positive and negative outcomes.

RESULTS

Data were extracted from 16 studies of the clinical effectiveness of SIT in the treatment of allergic rhinitis, involving 759 patients (546 adults, 53 children, 160 all ages). In 15 (94%) of the studies, investigators concluded that SIT was effective. In the remaining study (the only one conducted in children), investigators concluded that SIT was not effective. Symptoms of allergic rhinitis were more likely to improve in patients receiving SIT than in the comparison patients (OR 1.81, 95% CI 1.48 to 2.23). Symptom-medication scores were significantly lower in patients receiving SIT than in the comparison patients in all studies using such measures (P < 0.05).

CONCLUSION

Results of this analysis support the conclusion that SIT is effective in the treatment of allergic rhinitis.

Tree-pollen allergy is efficiently treated by short-term immunotherapy (STI) with seven preseasonal injections of molecular standardized allergens

The efficacy and tolerance of short-term immunotherapy (STI) by seven preseasonal injections of tree-pollen allergens (ALK7 Frühblühermischung) was investigated in a double-blind, placebo-controlled, multicenter study with 111 rhinoconjunctivitis patients. Nasal and bronchial symptoms simultaneously analyzed, and nasal symptoms as a single end point, but not the overall score of nasal, bronchial, and conjunctival symptoms, showed a significantly lower increase with STI during birch-pollen exposure (both P=0.033, n=105, Mann-Whitney U-test). However, a selective analysis with patients from centers with high recruitment figures (n> or =10 patients, n=29 STI, n=32 placebo) showed a significantly lower increase of nasal, bronchial, and overall symptom score (STI 11.0 vs placebo 18.0, P=0.001, U-test). STI had equidirected effects on conjunctival, nasal, and bronchial symptoms analyzed as multiple end points, although conjunctival symptoms were not significantly different as a single end point. The seasonal increase in drug use was reduced by 62% in the STI group compared with placebo (P=0.032, t-test). Specific IgG4 increased only after STI (P<0.001); IgE was not significantly different. Eosinophil cationic protein remained unchanged with STI, but significantly increased with placebo in the pollen season (P=0.003). STI was well tolerated. In conclusion, STI was shown to be efficacious and safe for the treatment of patients with tree-pollen rhinoconjunctivitis.

A method for production and determination of histamine releasing activity from human peripheral blood mononuclear cells

Histamine releasing factors, i.e. cytokines capable of inducing histamine release from basophils or mast cells, have been suggested to be involved in the pathogenesis of, for example, allergic late-phase reactions. Here we describe a controlled method for production and determination of histamine releasing activity (HRA) from human peripheral blood mononuclear cells (MNC). MNC were incubated with concanavalin A (Con A) for 2 h and cultured for another 40 h in fresh serum free medium. The culture supernatants were concentrated 19-25 fold by ultrafiltration (molecular weight cut-off: 3000 Da). The preparations of HRA induced dose- and Ca2+-dependent histamine release from leukocytes. Supernatants of parallel cultures of unstimulated MNC did not induce histamine release. The HRA was neither due to exogenous histamine releasing compounds (e.g. Con A) nor to residual histamine in the preparations of HRA. The kinetics of HRA induced histamine release (half-maximal release after > 40 min) were slower and more protracted than those of anti-IgE induced histamine release. However, based on a comparison between HRA induced histamine release from leukocytes and purified (97%) basophils, this did not appear to be due to an indirect effect on the basophils. Finally, neither the production of nor the response to HRA was dependent on the allergic status of the donor.

Comparison of histamine-releasing factor recovered from skin and peripheral blood mononuclear cells of patients with chronic idiopathic urticaria

BACKGROUND

The pathogenesis of chronic idiopathic urticaria is characterized by defective histamine release. Skin mast cells show an increased release of histamine while circulating basophils are less responsive to immunologic stimulus.

OBJECTIVE

The purpose of the study was to examine and compare the production of the histamine-releasing factor in the skin and within the peripheral blood of patients with chronic idiopathic urticaria and normal control subjects, as a possible factor responsible for the difference observed in the releasability of both skin mast cells and basophils.

METHODS

Using the skin chamber technique, histamine-releasing factor production and histamine concentration were assessed in normal-appearing skin of patients with chronic idiopathic urticaria (n = 12) and normal controls (n = 5) over a 2-hour observation period. In both groups, histamine-releasing factor production by peripheral blood mononuclear cells was also measured.

RESULTS

The weighted average of histamine-releasing factor production during the 2-hour observation period was higher in the non-lesional skin of patients with chronic idiopathic urticaria as compared with normal controls (5.6 +/- 1.4% versus 0.7 +/- 0.6%, P < .01). In contrast, less histamine-releasing factor was produced by peripheral blood mononuclear cells in chronic urticaria as opposed to normal controls (17.2 +/- 2.1% versus 25.7 +/- 2.8%, P < .03). Spontaneous histamine concentration was not significantly different in patients with chronic urticaria than in normal controls.

CONCLUSION

Histamine-releasing factor production is increased in the skin, and decreased in the peripheral blood of patients with chronic idiopathic urticaria when compared with nonatopic controls. The lower production of histamine releasing factor in the blood could be explained by the migration of activated T-lymphocytes in the skin.

Characterization of histamine releasing factors in diisocyanate-induced occupational asthma

Immunologic mechanisms contributing to diisocyanate-induced occupational asthma (OA) are poorly defined. There is a relatively low incidence of diisocyanate-specific IgE antibody responses. The frequent occurrence of delayed onset asthmatic responses in workers with diisocyanate asthma suggests a role for cellular immune mechanisms. We have shown in vitro production of antigen-specific mononuclear cell-derived histamine releasing factors (HRF) by peripheral blood mononuclear cells (PBMCs) of workers with OA. Monocyte chemoattractant protein-1 (MCP-1) and RANTES (acronym for "regulated on activation normal T expressed and secreted") are chemokines found in PBMC supernatants that express HRF activity. Diisocyanate-exposed workers were tested for diisocyanate antigen-stimulated enhancement of HRF, MCP-1, and RANTES production in supernatants of PBMCs and for serum specific IgE and IgG antibody levels to diisocyanate antigens bound to human serum albumin (HSA). PBMCs of workers with diisocyanate OA showed significantly increased production of antigen-specific HRF activity and MCP-1 ( > 300 ng/ml) compared to diisocyanate-exposed asymptomatic workers (P < 0.05). Antigen-stimulated enhancement of MCP-1 mRNA was demonstrated by reverse-transcription PCR. RANTES mRNA and chemokine secretion ( < 1 ng/ml) was also demonstrated in PBMCs, but did not show antigen enhancement in OA workers. Hapten specificity for the diisocyanate chemical to which a patient had been exposed was demonstrated for HRF enhancement and for IgG antibody reactions, but not for IgE reactions. HRF production was demonstrated in PBMC subpopulations, including lymphocytes and purified T cells. OA subjects showed increased CD8+ cells by immunofluorescence (mean CD4+: CD8+ = 1.2 +/- 0.2). The results suggest that diisocyanate antigen enhancement of HRF and MCP-1 production are stimulated by hapten-specific T cell reactions. Since a weak association has been found between IgE antibody synthesis and induction of diisocyanate OA, the role of T cell cytokines and chemokines in the pathogenesis of OA requires further investigation.

Grass pollen immunotherapy inhibits allergen-induced infiltration of CD4+ T lymphocytes and eosinophils in the nasal mucosa and increases the number of cells expressing messenger RNA for interferon-gamma

BACKGROUND

Grass pollen injection immunotherapy is effective in patients with summer hay fever, although efficacy must be balanced against possible side effects. The mechanism of immunotherapy is unknown but may be related to its ability to inhibit allergen-induced late responses, which are known to be characterized by infiltration of T lymphocytes, eosinophils, and cells with messenger RNA for so-called TH2-type cytokines (IL-4 and IL-5).

OBJECTIVE

This study was designed to observe the effect of grass pollen immunotherapy on late nasal responses and associated cellular infiltration and cytokine mRNA expression.

METHODS

We performed local nasal provocation with grass pollen (and a control challenge) in 28 patients after a 12-month double-blind, placebo-controlled trial of immunotherapy. Nasal biopsy specimens were obtained at 24 hours and processed for immunohistology and in situ hybridization studies.

RESULTS

Grass pollen immunotherapy inhibited allergen-induced immediate (0 to 60 minutes) increases in sneezing (p < 0.02) and nasal blocking (p < 0.01) and late (0 to 24 hours) nasal symptoms (p < 0.05). Immunotherapy also inhibited the associated infiltration of the nasal mucosa by CD4+ T lymphocytes and total (major basic protein-containing) and "activated" (cationic protein-secreting) eosinophils (all p = 0.03). There was a significant (p = 0.04) increase in cells expressing mRNA for interferon-gamma at 24 hours after allergen challenge, which correlated inversely with patients' seasonal symptoms (r = -0.65, p < 0.05) and medication requirements (r = -0.75, p < 0.02) during the pollen season.

CONCLUSION

The results suggest that successful grass pollen immunotherapy for summer hay fever may act by inhibiting allergen-induced T lymphocyte and eosinophil recruitment and eosinophil activation in the target organ, possibly through a mechanism involving protective local increases in TH1-type cells.

Chemokines in seasonal allergic rhinitis

Monocyte chemotactic and activating factor/monocyte chemoattractant protein-1 (MCAF/MCP-1), RANTES, and macrophage inflammatory protein (MIP)-1 alpha are chemokines known to activate basophils (MCAF/RANTES) and eosinophils (RANTES/MIP-1 alpha). IL-8 inhibits MCAF-induced histamine release from basophils. We questioned whether a relationship exists between the levels of these chemokines and various inflammatory mediators released from mast cells, eosinophils, and basophils as assessed in nasal secretions obtained from patients during the allergy season and out of season. Samples were assessed for MCAF/MCP-1, RANTES, MIP-1 alpha, IL-8, histamine, tryptase and eosinophil cationic protein (ECP) in three subject groups: subjects with allergic rhinitis (n = 18), atopic subjects without rhinitis (n = 9), and healthy individuals (n = 6). Statistically significant differences were apparent only in the subjects with symptoms as follows. MCAF/MCP-1 increased during the season from 336 +/- 47 pg/ml to 829 +/- 137 pg/ml (p < 0.001), whereas IL-8 decreased from a baseline of 1932 +/- 335 pg/ml to 1070 +/- 202 pg/ml (p < 0.028). The ratio of IL-8 to MCAF/MCP-1 decreased during the symptomatic season from the baseline of 6.66 +/- 1.06 seen during winter to 1.3 +/- 0.22 during ragweed season (p < 0.001). Histamine increased from 6.3 +/- 1.5 to 89 +/- 15.5 ng/ml (p < 0.001), ECP increased from 20.6 +/- 6.4 to 237.1 +/- 50.2 ng/ml (p < 0.001), and tryptase increased from 2.34 +/- 0.6 to 9.7 +/- 2.3 U/ml (p < 0.001). Most samples did not have detectable quantities of MIP-1 alpha or RANTES. We also found a correlation between the level of MCAF/MCP-1 and IL-8 and the level of histamine or IL-8 and ECP. Our results suggest that the chemokines MCAF/MCP-1 and IL-8 may participate in the pathogenesis of allergic rhinitis, contributing to the attraction of the proinflammatory cells and mediator release, which might be very important during the late phase of the allergic reaction. Furthermore, the ratio of certain chemokines, such as MCAF/MCP-1 and IL-8 may reflect the magnitude of the reaction, as does the presence of histamine and ECP.

Chemokines and the allergic response

The beta subfamily of chemokines contains cytokine-like factors which are chemotactic for human basophils and eosinophils. The also stimulate these cells to secrete pro-inflammatory substances such as histamine or eosinophil cationic protein. MCAF/MCP-1, MCP-2, MCP-3, RANTES and MIP-1 alpha all attract and stimulate basophils; MCP-1 and MCP-3 are the most potent. RANTES, MCP-3 and to a lesser degree MIP-I alpha are chemotactic factors and activators of eosinophils. Cytokines such as IL3, IL5 and GM CSF can augment the responses of these cells to the various chemokines and function as primers. These substances may have particular importance as mediators of allergic inflammation, particularly the late phase component of the response.

Possible dual role of anti-idiotypic antibodies in combined passive and active immunotherapy in honeybee sting allergy

BACKGROUND

Passive infusion of beekeepers' plasma was shown to protect patients against systemic reactions occurring during active immunotherapy by mechanisms still to be clarified. It is tempting to speculate that anti-idiotypic antibodies could play a role because they are found in beekeepers' plasma and are involved in the regulation of IgE synthesis.

METHODS

In this report we studied the effects of passive infusion of a beekeeper's plasma rich in anti-idiotypic antibodies to a patient who experienced systemic reactions to honeybee venom.

RESULTS

We reported, during the days after the infusion, a decrease of clinical sensitivity to the honeybee venom. Indeed, the patient tolerated a cumulative dose of 280 micrograms of venom without adverse reactions. We also observed decreases in skin mast cell and in basophil sensitivity. After the plasma infusion, a modified rush immunotherapy with honeybee venom was initiated in our patient. In the following 76 weeks, increased levels of anti-idiotypic antibodies in the serum of the patient were associated with a diminution of specific antibodies (IgG and IgE) to honeybee venom.

CONCLUSION

These results suggest a dual role of anti-id in our combined protocol of passive and active immunotherapy: an immediate action on clinical sensitivity along with a decrease of skin mast cell and basophil sensitivity and an immunoregulatory role on specific antibody production.

The effect of immunotherapy on the cutaneous late phase response to antigen

BACKGROUND

This study used the skin chamber model to evaluate prospectively the effect of immunotherapy (IT) on the cutaneous early and late phase response (LPR) to epicutaneous antigen challenge.

METHODS

Nine subjects with allergic rhinitis were studied at three time points: before starting IT, after 3 months of IT, and after 6 months of IT. Skin chamber histamine content was measured hourly for 12 hours, and cell counts performed hourly during hours 6 to 12. An intradermal skin test was placed, and the reaction was measured hourly for 12 hours. Skin biopsy specimens were obtained 8 hours after intradermal placement and evaluated for cellular infiltrate and major basic protein deposition. Serum antigen-specific IgG and IgE levels were measured at each time point to confirm physiologic effect of IT.

RESULTS

Six months of IT significantly (p < 0.05) decreased both early and LPR skin test reactivity and skin chamber histamine for hours 1 to 3, 4 to 6, and 9 to 12. Skin chamber LPR cellular influx decreased significantly (p < 0.05) for neutrophils only. Decrease in LPR histamine after 6 months of IT was significantly correlated with both decrease in mononuclear cells (R2 = 0.817, p = 0.002) and decrease in neutrophils (R2 = 0.813, p = 0.009). Also significantly correlated were decrease in LPR skin test reactivity, with percent change in skin chamber mononuclear cells (R2 = 0.800, p = 0.009) and decrease in early skin test reactivity (R2 = 0.675, p = 0.01). Biopsy specimens showed no consistent change in either dermal cellular infiltrate or deposition of major basic protein.

CONCLUSION

IT significantly attenuates cutaneous histamine release and skin test reactivity and is accompanied by a decrease in skin chamber LPR neutrophil influx without significantly altering the dermal infiltrate at 8 hours.

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.

Spontaneous histamine release in whole blood in patients before and after 4 months of specific immunotherapy

Spontaneous histamine release (SHR) in whole blood was assessed before and after 4 months of specific immunotherapy (SIT) for allergic rhinoconjunctivitis in 32 patients. Spontaneous histamine release was significantly enhanced (P < 0.05) in patients prior to immunotherapy compared with 20 controls. Spontaneous histamine release decreased significantly in patients after 4 months of specific immunotherapy (P < 0.04) and almost reached the same values as spontaneous histamine release in controls. Clinical success of treatment after 4 months was seen in 15 patients (improvement > or =50%), 10 of whom showed a significant decrease in spontaneous histamine release. Decrease of spontaneous histamine release after 4 months indicates the efficacy of specific immunotherapy already at an early stage of treatment. Assessment of spontaneous histamine release appears to be a useful and easily performable method for monitoring success of treatment of patients during specific immunotherapy.

HRF of 30 kDa: evidence for active synthesis

A variety of mediators are involved in the pathophysiology of a number of clinical conditions. Among them histamine-releasing factors (HRF) act as secretagogue for basophils and mast cells to cause cell degranulation and histamine release. Studies on the kinetics of HRF production by activated mononuclear cells (MNC) have suggested an active synthesis of this cytokine. Using a [35S]-metabolic cell labeling method, we first analyzed the capacity of MNC from patients with allergic rhinitis to ragweed to actively synthesize HRF. We then found that stimulation of MNC with allergen promoted a synthesis of large quantities of proteins, including a protein of about 30 kDa. Secondly, we developed a method for the enrichment of HRF molecules from crude supernatants of ragweed-stimulated MNC using ion exchange and gel filtration chromatography. We observed that the yield of HRF activity is seen just before the chymotrypsinogen marker. The estimated molecular weight was 30-35 kDa.