[ICAM-1 and allergic inflammation]

Recent progress in the understanding of the physiopathology of asthma makes possible the revision of the objectives of treatment, to pass from short-term symptomatic control to a prolonged control of the illness. L'ICAM-1 is an excellent potential target for preventative treatment of asthma of viral origin. When there are agents available of both inhibiting histamine and positively regulating ICAM-1 there is no longer reason to use simple antihistamines.

Allergen-specific conjunctival challenge in asthma. An additional diagnostic tool to define sensitization

Reversible airway obstruction and airway inflammation following allergen exposure represent crucial pathophysiological features of allergic asthma. In order to investigate these events, bronchial-specific challenge is commonly employed although it may be complicated and may not be free of possible risks. Therefore, we evaluated the applicability of allergen-specific conjunctival challenge (ASCC) in adults with asthma to define the diagnosis of specific sensitization and the grade of specific sensitization, and to detect the presence of allergic inflammation. As recently described, conjunctival challenge represents an easy diagnostic tool in allergic inflammation. We studied 30 symptomless patients with a history of mild asthma, including 20 allergic patients, 10 females and 10 males (18-48 years old), sensitized to Parietaria judaica only, with a history of recurrent asthma attacks during seasonal natural exposure to allergen, 10 nonallergic patients, 7 females and 3 males (28-55 years old), with a history of recurrent asthma attacks unrelated to any allergen exposure, and 10 healthy volunteers as controls. The study was performed outside the pollen season. The ASCC induced a highly significant early-phase clinical reaction and a highly significant inflammatory cell infiltrate in the asthmatic patients sensitized to P. judaica when compared to other study groups (p < 0.001). The ASCC showed as 100% sensitivity, specificity, predictive value of positive and negative results in the group of sensitized asthmatic patients when compared to unsensitized ones and to healthy subjects. The study confirms the reproducibility and usefulness of ASCC to diagnose allergy and to define its grade. These data strongly suggest ASCC employment also in patients with a single history of allergic asthma.

Molecular events in allergic inflammation: experimental models and possible modulation

In recent years, a complex molecular network involving cytokines kinins and adhesion molecules has been demonstrated to operate in allergic inflammation. In particular, the adhesion machinery plays a crucial role for the recruitment and locomotion of the inflammatory cells and the Intercellular Adhesion Molecule 1 (ICAM-1) is a hallmark of the allergic inflammatory process. The role and possible modulation of ICAM-1 can be investigated using both eye and nose experimental models. Conjunctival and nasal epithelium are easy to study either under natural allergen exposure or after specific/aspecific provocation tests; furthermore the nasal/conjunctival challenge is well tolerated by the patients. These experimental models have allowed us to investigate in vivo the antiallergic properties of several compounds. Many of the new antihistamines, but also deflazacort and local nasal immunotherapy, were demonstrated capable of reducing both inflammatory infiltration and ICAM-1 expression on epithelia. Because of the central role of adhesion molecules in allergic inflammation, their pharmacological modulation can be regarded as a promising therapeutic approach.

Local nasal immunotherapy: experimental evidences and general considerations

The possibility of local hyposensitization in allergies was envisaged since the first decades of the century and then sporadically employed, whereas controlled clinical trials of local nasal immunotherapy (LNIT) were performed only during the last 20 years. Studies currently available agree on the clinical efficacy of the treatment. LNIT was demonstrated capable of reducing symptoms both in pollen- and mite-induced rhinitis, and of modifying the specific target organ responsivity. Indeed, aqueous extracts appeared to be more effective than modified ones but were also charged by troublesome local side effects, while the recently introduced powdered extracts seemed to overcome this problem, maintaining a favourable clinical effectiveness. In a recent study we demonstrated a significant effect of LNIT on local allergic inflammation. LNIT reduced both the inflammatory infiltration and ICAM-1 expression on nasal epithelial cells upon specific nasal challenge. The effects on specific challenge appeared long-lasting, but the clinical efficacy seemed to depend strictly upon preseasonal treatment. LNIT with powdered extracts appears an effective, safe and well-tolerated treatment for allergic rhinitis. Nevertheless, its particular administration technique requires a careful choice of patients. Finally, a socioeconomical analysis shows a favourable cost/benefit ratio for LNIT if compared to classic subcutaneous immunotherapy.

Topical azelastine reduces eosinophil activation and intercellular adhesion molecule-1 expression on nasal epithelial cells: an antiallergic activity

BACKGROUND

It is well known that allergen-specific nasal challenge (ASNC) is a fruitful tool with which to evaluate antiallergic activity exerted by a drug. Azelastine is a new antihistamine also available in topical form (i.e., nasal spray).

OBJECTIVE

The aim of the study was to evaluate the effects of azelastine nasal spray on inflammatory changes after ASNC in both the early-phase reaction and the late-phase reaction.

METHODS

The study had a double-blind, placebo-controlled, randomized, and parallel-group design. Twenty patients with pollen allergy were enrolled out of pollen season. ASNC was performed at baseline (TO) and after 1 week of washout (T7). At T7, 10 patients sprayed azelastine (1 puff) into their nostrils, and 10 patients used placebo. ASNC was performed after 30 minutes. The considered parameters (evaluated during early- and late-phase reactions) were: (1) clinical signs and symptoms, (2) cytologic assessment (neutrophils and eosinophils), (3) assay-of mediators (eosinophil cationic protein and myeloperoxidase), and (4) expression of intercellular adhesion molecule-1 (ICAM-1) on nasal epithelial cells. We focused our attention on ICAM-1 because it is the natural ligand of leukocyte functional associated antigen-1 and Mac-1, expressed on eosinophils. In addition, ICAM-1 is expressed on epithelial cells only on allergen exposure (both natural and experimental).

RESULTS

Placebo did not exert any modification on the considered parameters. After azelastine administration, significant decreases in total symptom score, eosinophilic and neutrophilic infiltration, and ICAM-1 expression were observed during both early- and late-phase reactions. Furthermore, serum eosinophil cationic protein levels decreased during the late-phase reaction, whereas myeloperoxidase was not affected by the treatment. These findings were confirmed by the powerful Koch's split-plot statistical analysis.

CONCLUSION

Azelastine exerts antiallergic activity, mainly affecting eosinophil function and downregulating ICAM-1 expression, on nasal epithelial cells.

Antiallergic activity of topical lodoxamide on in vivo and in vitro models

Lodoxamide is an antiallergic drug acting as a mast-cell stabilizer, which is effective in the treatment of allergic conjunctivitis. The study aimed to evaluate the effect of lodoxamide eye-drops on the inflammatory early-phase reaction (EPR) changes induced by allergen-specific conjunctival challenge (ASCC). This was a cross-over, double-blind, placebo-controlled, randomized study, including 10 outpatients suffering from allergic rhinoconjunctivitis due to Parietaria judaica. Patients received one drop of lodoxamide tromethamine 0.1% or placebo 30 min before each ASCC. Clinical evaluation and cytologic assessment were done at baseline and 30 min after each ASCC. Lodoxamide induced a reduction in total symptom score and hyperemia during the EPR (P < 0.05). Lacrimation, itching/burning, and eyelid swelling were only slightly (nonsignificantly) reduced. Lodoxamide induced a reduction in the total number of inflammatory cells and neutrophils during the EPR (P < 0.02). Eosinophil and lymphocyte number and ICAM-1 expression showed only a slight, not statistically significant decrease. Placebo did not affect the studied parameters. Lodoxamide reduced early clinical events and cellular changes after ASCC consistently with its activity as mast-cell stabilizer. Moreover, lodoxamide was able to downregulate in vitro ICAM-1 expression on the continuously cultured, differentiated conjunctival cell line WK. This was shown both in basal conditions (P < 0.05) and upon interferon-gamma stimulation (P < 0.03), although at high concentration.

Increase of asthma and allergic rhinitis prevalence in young Italian men

Our previous studies have reported that the prevalence of asthma was 2.89% and of allergic rhinitis 1.54% in Ligurian conscripts for the army during 1983. Since several authors reported an increasing prevalence of these diseases in different geographic areas, the aim of the present study was to evaluate the trend of prevalence rates in a same homogeneous group of Ligurian conscripts. The prevalence of asthma and allergic rhinitis was assessed in a group of 4310 young Ligurian men (18 years old) who had undergone medical examination for call-up to the navy during 1993, 1994 and 1995. Subjects were investigated by history, clinic visit, spirometry, metacholine bronchial challenge and skin prick test. The prevalence of asthma is 4.39% and of allergic rhinitis 2.2%. Comparing these results with previous data, a significant increase appears in this area 12 years later (respectively, p < 0.001 and p < 0.006). In addition, the association with asthma in allergic rhinitics increases from 41 to 77%, as well as an increasing trend appears for perennial allergens (i.e. mites and cat) and the polysensitizations increase from 48 to 67%. Possible explanations for these phenomena might be due to environmental factors (i.e. pollutants, viral infections, changes in domestic microenvironment).

[Anti-leukotriene agents: rationale for and prospects of use]

Leukotrienes (LT) are synthesized from arachidonic acid by several enzymes such as phospholipase A2, 5-lipoxygenase, LTC4 synthase, as a consequence of a wide range of inflammatory stimuli. Leukotrienes seem to play a pivotal role in the maintenance of the inflammatory processes as they exert numerous biological activities, i.e. chemotactic action on polymorphonuclear cells, bronchospastic action, vasodilator and secretagogue effects. Thus, the inhibition of LT activity may result in antiinflammatory action. Several compounds capable of blocking either LT synthesis or LT receptors have recently been developed and clinically tested in different experimental models. In particular, encouraging results have been obtained in the asthma model, but interesting clinical observations have also been performed in psoriasis, ulcerative colitis and rheumatoid arthritis. Although further studies and optimization of this kind of treatment are required, a possible clinical role of LT antagonists as antiinflammatory therapy for selected diseases may be envisaged.

Intraepithelial gamma/delta-positive T lymphocytes and intestinal villous atrophy

We have evaluated the expression of different molecular forms of T cell antigen receptor (TcR) in duodenal biopsies of pediatric patients with different forms of villous atrophy: celiac disease, autoimmune enteropathy, intractable diarrhea of unknown origin, and severe cow milk intolerance. A panel of monoclonal antibodies recognizing alpha/beta and gamma/delta TcR (and gamma/delta TcR subsets) was used for immunostaining. The results showed an increase of T cells with gamma/delta-type TcR in celiac patients and also in patients with other forms of villous atrophy with respect to normal controls. Amongst the gamma/delta TcR-positive cells, the subset expressing the molecular product of V delta 1 region was the most represented. The gamma/delta TcR-positive T cells were mainly located within the epithelium: few of them were observed in the lamina propria. On the basis of these results, we hypothesize that the increased homing of gamma/delta TcR-positive T lymphocytes in gut epithelium observed in celiac disease is, at least in part, related to villous atrophy per se.

Cetirizine reduces ICAM-I on epithelial cells during nasal minimal persistent inflammation in asymptomatic children with mite-allergic asthma

It has been recently demonstrated that individuals who suffer from mite allergy present mucosal inflammation even when asymptomatic. This situation is characterized by infiltration of inflammatory cells (eosinophils and neutrophils) and by ICAM-I expression on epithelial cells. It has been called 'minimal persistent inflammation' (MPI) for its relationship with natural exposure to allergen, which is continuous in the case of mite allergy. ICAM-I (or CD54) expression on epithelial cells is relevant for several reasons: (a) healthy individuals and patients with pollen allergy out of the pollen season do not express this molecule; (b) ICAM-I is the natural ligand of LFA-1 (an integrin expressed on granulocytes), and (c) ICAM-I is also receptor for rhinoviruses. It is well known that viral infections precede asthmatic attacks; consequently, this correlation is more frequent in cases of mite allergy. Cetirizine is an antiallergic drug that can reduce both inflammatory infiltrate and ICAM-I expression induced by allergen-specific conjunctival challenge. The aim of this study was to evaluate the effect of cetirizine on MPI in 20 children (5-14 years old) with mite allergy. All the children suffered from mild asthma and 9 also had rhinitis (they had been asymptomatic, and thus not treated, for 2 months). The study was double-blind, placebo controlled and randomized and children took Cetirizine or placebo for 15 days. At the beginning and end of the study, nasal scrapings were performed to evaluate inflammatory cell infiltration (eosinophils and neutrophils) and ICAM-I expression on epithelial cells. Cetirizine-treated children showed a significant reduction (or even total absence) of ICAM-I expression on epithelial cells (p less than 0.002) and a reduction trend in inflammatory cell counts compared with placebo. In conclusion, Cetirizine might be envisaged as fruitful for the prolonged treatment of allergic children, including during clinical latency, to prevent possible relapse or rhinovirus infections.

Alternative routes for allergen-specific immunotherapy

The alternative routes for allergen-specific immunotherapy (oral, sublingual, intranasal) have the overall aim of minimizing or avoiding the possible side-effects caused by the injectory route, and of making the treatment more convenient and acceptable for the patients. The clinical efficacy and the safety of the alternative routes have been clearly demonstrated in many controlled studies for the most common inhalant allergens. The oral routes appear particularly suitable for children and patients with unsatisfactory compliance with the injectory route. On the other hand, nasal immunotherapy, because of its peculiar administration technique, requires a careful choice of well-trained adult patients. In conclusion, the good tolerability, safety and socioeconomic benefits strongly support the use of alternative routes as valid therapeutic options for the treatment of respiratory allergy.

Adhesion molecules in allergy

Cell adhesion molecules have been recognized to play a major role in a variety of physiological and pathophysiological phenomena, such as embryogenesis, maintenance of tissue architecture and tissue damage repair, recruitment of leukocytes into tissues, immunological reactions requiring cell-to-cell contact. Their role in inflammatory reactions is crucial, in particular their involvement in allergic inflammation has been extensively studied. It has become apparent that the expression patterns and cell localization of certain adhesion molecules are related to the dynamic of allergic inflammation, and specifically to selective migration of eosinophils and interactions with epithelial cells of the target organs. In some instances, cell adhesion molecules by themselves may be regarded as reliable markers for clinical purposes. In addition, the pharmacological modulation of expression and release of adhesion molecules may provide new insight about the mechanisms of action and effectiveness of antiallergic drugs.

Minimal persistent inflammation is present at mucosal level in patients with asymptomatic rhinitis and mite allergy

The natural exposure to house dust mites causes sensitization in genetically susceptible patients. Persistent exposure of sensitized patients causes chronic inflammation, and consequently, hyperreactivity, thus promoting the development of clinical features. Recently, intercellular adhesion molecule-1 (ICAM-1)/CD54 expression on epithelial cells triggered by allergen has been demonstrated and related to the inflammation caused by the allergic reaction. Therefore we evaluated the possible presence of inflammation (i.e., inflammatory cell infiltrate and ICAM-1/CD54 expression on epithelium) at conjunctival and nasal levels in patients with asymptomatic allergic rhinitis caused by mites, in their relatives living in the same environment, and in healthy volunteers. In addition, the possible relationship between inflammation and house dust mite allergen exposure was evaluated. Conjunctival and nasal scrapings of allergic subjects enrolled in the study showed many inflammatory cells. A mild ICAM-1/CD54 expression on conjunctival and nasal epithelium was detectable in allergic subjects, whereas relatives and healthy volunteers showed few inflammatory cells and no ICAM-1/CD54 expression on epithelial cells. A detectable level of house dust mite, sufficient to cause sensitization, was found in all houses. This study demonstrates a minimal persistent inflammation at conjunctival and nasal levels constantly detectable in patients without symptoms who are sensitized to mites and continuously exposed to the natural allergens.

Studies on the relationship between the level of specific IgE antibodies and the clinical expression of allergy: I. Definition of levels distinguishing patients with symptomatic from patients with asymptomatic allergy to common aeroallergens

BACKGROUND

The detection of specific IgE antibodies to environmental allergens does not always coincide with a diagnosis of clinically evident allergic disease, because some patients with positive skin and/or in vitro test results have no symptoms related to the allergen or allergens that induced the antibodies.

OBJECTIVE

In a multicenter study the optimal cutoff values for specific IgE antibody levels and skin test results that could discriminate between patients with symptomatic and those with asymptomatic allergy were determined.

METHODS

IgE antibodies specific for a panel of common aeroallergens were assayed with the Pharmacia CAP System (Pharmacia, Uppsala, Sweden) in two groups of patients, a group of 267 patients with symptomatic allergy and a group of 232 with asymptomatic allergy--both with positive skin prick test results--and in a group of 243 healthy, nonallergic control subjects. The cutoff values were established by receiver operating characteristic analysis.

RESULTS

A significantly higher mean specific IgE antibody value was found in patients with symptomatic allergy compared with patients with asymptomatic allergy (p < 0.001) and in patients with symptomatic allergy compared with healthy control subjects (p < 0.001). The optimal CAP System cutoff value between patients with symptomatic and those with asymptomatic allergy was 11.7 kU/L, and when seasonal allergens were compared with perennial allergens, the cutoffs were 10.7 kU/L and 8.4 kU/L, respectively. The optimal cutoff value for the skin prick test was a wheel area of 32 mm2 for seasonal allergens and 31 mm2 for perennial allergens. The skin test had a lower diagnostic value (sum of sensitivity and specificity) than the CAP System.

CONCLUSIONS

Cutoff values for specific serum IgE antibody levels are likely to be useful in clinical practice to distinguish symptomatic from asymptomatic allergy in patients with positive skin test results.

Oxatomide reduces inflammatory events induced by allergen-specific conjunctival challenge

BACKGROUND

Allergen-specific conjunctival challenge is a safe and reproducible experimental model to evaluate effectiveness and possible mechanism(s) of action of drugs employed in the treatment of allergic diseases.

OBJECTIVE

The protective effect of oxatomide on inflammatory changes that follow allergen-specific conjunctival challenge was assessed in 20 patients with rhinoconjunctivitis due to Parietaria judaica in a double-blind study.

METHODS

After a screening allergen-specific conjunctival challenge, patients were randomized into two treatment groups, each being given oxatomide (oral tablets) at 60 mg daily or matching placebo for seven days during off-pollen season. Clinical evaluation, cytologic assessment (number of inflammatory cells and ICAM-1 expression on epithelial cells) were assessed at baseline, 30 minutes, 6 hours, and 24 hours after allergen-specific conjunctival challenge, before and after treatment. In addition, electrocardiograms were obtained before and after treatment.

RESULTS

Early phase reaction clinical events as well as total numbers of inflammatory cells were significantly reduced by oxatomide compared with placebo. Late phase reaction clinical events as well as total numbers of inflammatory cells were significantly reduced by oxatomide compared with placebo. ICAM-1 expression was significantly reduced by oxatomide in early phase reactions and late phase reactions compared with placebo. No pathologic cardiac events were detected in any subject.

CONCLUSIONS

Oxatomide has a protective effect on clinical and cellular early phase reactions and late phase reactions (including ICAM-1 expression on epithelium) induced by allergen-specific conjunctival challenge and is safe and well tolerated.

Quantitative determination of fibronectin (FN): evaluation of immunoturbidimetric and rate nephelometric techniques for FN assay in the different biologic materials

Aim of this study is to determine fibronectin concentration in the different biological materials to study its changes in the anatomic districts where the cell interactions in which FN participates do occur. The traditional immunoturbidimetric method and the nephelometric method are compared. An alternative method using a support for the collection of very small samples is proposed and the results obtained are discussed. This approach with solid phase immunonephelometry can be used both in amounts of biological fluids too small for traditional methods and in concentrations < 4.5 mg/dL. It is hoped that less complex techniques will be studied, allowing routine tests that can be performed by all laboratories. Unfortunately, at present this method is still investigated, however, it would be useful to adopt it in case of difficult sample collection.

Terfenadine exerts antiallergic activity reducing ICAM-1 expression on nasal epithelial cells in patients with pollen allergy

BACKGROUND

Rhinoconjunctivitis caused by pollen allergy is characterized by typical signs and symptoms and mucosal infiltration by inflammatory cells during the pollen season. It has recently been demonstrated that the adhesion molecule system is deeply involved in cell-to-cell interaction during the inflammatory response which follows allergic reactions.

OBJECTIVE

The aim of the present study (placebo-controlled, double-blind, randomized) was the evaluation of the antiallergic activity of Terfenadine in the model of the allergic rhinitis due to natural pollen exposure.

METHODS

Two groups of patients with pollen allergy were enrolled in this study. Ten patients were treated with Terfenadine (120 mg/die) for 7 days and 10 with placebo. Evaluation criteria were: (a) clinical: signs and symptoms (recorded daily in a diary card by patients); (b) cytological: inflammatory cell count (neutrophils, eosinophils, metachromatic cells) from nasal lavage at T0 and T7; (c) immunocytochemical: ICAM-1/CD54 expression on nasal epithelial cells at T0 and T7; and (d) mediators dosage (ECP-MPO) on nasal lavage at T0 and T7.

RESULTS

As opposed to the placebo group, patients treated with Terfenadine showed a significant improvement of both symptoms (P < 0.022) and signs P < 0.001), a significant reduction of inflammatory cells infiltrate (P < 0.005), of ECP levels (P < 0.002) and ICAM-1 expression on nasal epithelial cells (P < 0.005).

CONCLUSIONS

In conclusion, these data demonstrate that Terfenadine exerts antiallergic activity since it is able to reduce inflammatory cell infiltrate and downregulates ICAM-1 expression.

Loratadine in the treatment of cough associated with allergic rhinoconjunctivitis

BACKGROUND

Antihistaminic treatment of allergic asthma or cough-type asthma, including cough associated with allergic rhinocojunctivitis, has been recently reconsidered prospectively since new very potent compounds, nonsedating with anti-allergic properties, are available.

OBJECTIVE

The possible effectiveness of loratadine in the treatment of allergic cough was assessed in 20 patients with allergic rhinoconjunctivitis and cough due to Parietaria judaica during the pollen season (April to July 1993).

METHODS

Allergic patients were enrolled in a double-blind, placebo-controlled, parallel-group, randomized study, and received loratadine 10 mg/d or placebo in oral tablets for 4 weeks. Occurrence and severity of conjunctival and nasal symptoms, severity and frequency of cough attacks were assessed daily by the patients together with peak expiratory flow evaluation performed twice a day, ie, in the morning and in the evening. Physicians evaluated conjunctival and nasal signs, and spirometry on admission (before treatment), 2 and 4 weeks after treatment. On admission methacholine challenge was also performed to assess PD20. Pollen counts were assessed during the study.

RESULTS

According to patients' diary cards, ocular and nasal symptoms were progressively reduced by loratadine treatment (respectively P < .05 and P < .01), as well as cough frequency (P < .05) and cough intensity (P < .01). Peak expiratory flow rate, forced vital capacity, and forced expiratory volume in one second significantly decreased in the placebo-treated group (P < .01), while they were not modified in loratadine-treated patients, who remained normal.

CONCLUSIONS

The study suggests that loratadine may be beneficial in the treatment of allergic cough, as well as in rhinoconjunctivitis. Further studies of this may be warranted.

Nasal immunotherapy to Parietaria: evidence of reduction of local allergic inflammation

Studies over 10 yr have demonstrated local nasal immunotherapy (LNIT) to be an effective treatment for rhinitis due to pollens and mites. The aim of our work was to investigate the effects of LNIT on the local inflammatory phenomena, employing the model of nasal allergenic challenge, since no evidence has been yet provided about LNIT effects on the events due to allergic reactions. We evaluated, in addition, the possible effects of LNIT on some systemic immunologic parameters and its clinical efficacy. The study involved a double-blind, placebo-controlled trial of preseasonal immunotherapy with Parietaria in 20 adults. A significant reduction of symptoms, inflammatory infiltration, and intercellular adhesion molecule-1 (ICAM-1) expression on epithelial cells after nasal challenge was evidence as long-lasting effect. No changes in serum allergen-specific IgE, IgG, and soluble eosinophil cationic protein were detected, whereas an unexpected increase of soluble ICAM-1 was found in the placebo group only. The treatment was well tolerated and a significant clinical improvement under natural allergenic exposure was observed in the active group. The present study provides, for the first time, evidence that LNIT is able to modulate the nasal allergic inflammation.

ICAM-1 on epithelial cells in allergic subjects: a hallmark of allergic inflammation

Allergen-specific challenge was first shown to induce ICAM-1 expression on epithelial cells (ECs) of conjunctiva in allergic patients. The data have also been confirmed in the nose. We then checked for the presence of ICAM-1 consequent to natural exposure to allergens. For both conjunctivitis and rhinitis due to pollen we confirmed, during the pollen season, the presence of ICAM-1 on ECs. We demonstrated the endogenous source of ICAM-1 by in situ hybridization both in vitro and in vivo. ICAM-1 could be an activation marker on ECs, or could, enhanced EC susceptibility to bind offending cells such as eosinophils (LFA-1+). ICAM-1 is also a receptor for the vast majority of rhinoviruses, which are known to provoke, mainly in children, asthma attacks. Since we found that mite allergens can induce ICAM-1 on ECs, even during clinical latency, allergy may be considered as a primary event leading to asthma (through rhinovirus infection) and non-specific hyperreactivity.

Follicular thyroid cells of autoimmune thyroiditis may coexpress ICAM-1 (CD54) and its natural ligand LFA-1 (CD11a/CD18)

The leukocyte functional associated antigen-1 (LFA-1)-intercellular adhesion molecule-1 (CD11a-CD18/CD54) intercellular adhesion system plays a crucial role in several immunologic phenomena, including adhesion between lymphocytes and epithelial cells. In previous studies evidence for CD54 expression on thyroid follicular cells in Hashimoto's thyroiditis was provided. In this study we evaluated the possible expression of CD11a and CD18 antigens on thyrocytes of patients with Hashimoto's thyroiditis and on thyrocytes of patients with Graves' disease and simple goiter as controls; we used both alkaline phosphatase immunostaining and indirect immunofluorescence on cryostatic tissue sections. The results showed that LFA-1 (both CD11a and CD18) positivity on thyroid follicles may occur in glands of patients with Hashimoto's disease, with a pattern very similar to that of CD54: this was observed in five of seven specimens. Conversely, no positivity was observed in tissues from patients with Graves' disease or goiter: notably, isolated follicular cells from Graves' goiter tissues are induced in culture to express CD54, but not LFA-1. Using double-staining techniques, we were able to show that in specimens from patients with Hashimoto's disease, the same follicular structures coexpressed LFA-1 and CD54. Such a coexpression of the two ligands further emphasizes the possible role of this adhesion system in the pathogenesis of epithelial damage, through bidirectional interactions between thyroid epithelial cells and infiltrating LFA-1 or CD54-positive mononuclear cells.