Heterogeneity of specific-IgE responses in workers sensitized to acid anhydride compounds

Acid anhydride compounds cause IgE-mediated respiratory sensitization in the workplace. In this study reaginic responses in four workers sensitized to phthalic anhydride (PA), hexahydrophthalic (HHPA), or himic anhydride (HA) were determined by direct RAST by use of PA-human serum albumin (HSA), HPPA-HSA, and HA-HSA methylcellulose disc substrates. RAST inhibition of binding to anhydride-HSA substrates was done with various concentrations of sodium salts, lysine, and HSA conjugates of PA, HHPA, HA, and trimellitic anhydride (TMA) in order to characterize cross-reactivity and specificity of humoral responses in these workers. Molar concentrations of anhydride bound to lysine and HSA carriers were assayed by protein hydrolysis followed by gas chromatographic analysis. Significant direct RAST binding against PA-HSA, HHPA-HSA, and HA-HSA was found in all four workers. PA-HSA-IgE binding in one PA-sensitive worker (no. 1) was inhibited significantly by PA-HSA alone and not by sodium PA or PA lysine. In contrast, another PA-sensitized worker (no. 2) exhibited 50% inhibition of PA-HSA binding by PA-HSA (1 X 10(-9) M), PA-lysine (7 X 10(-8) M), and NaPA (1 X 10(-7) M); no inhibition of PA-HSA by heterologous HHPA-, HA-, or TMA-inhibitory reagents was found in either of the PA workers. RAST binding to HHPA-HSA in the HHPA-sensitive worker was inhibited by HHPA-HSA alone.(ABSTRACT TRUNCATED AT 250 WORDS)     

Nasal challenge shows pathogenetic relevance of specific IgE serum antibodies for nasal symptoms caused by hexahydrophthalic anhydride

Abstract. Hexahydrophthalic anhydride (HHPA) is a component of some epoxy resin systems, A high fraction of HHPA-exposed workers display nasal symptoms, and some of them have specific serum antibodies. To test the pathogenetic relevance of the antibodies, nasal challenge tests were performed with a conjugate of HHPA and human serum albumin (HSA) at three increasing concentrations. Eleven subjects, who were IgE-sensitized against HHPA (positive in RAST and in skin-prick test against the HHPA-HSA conjugate), and who reported work-related nasal symptoms, had a significant increase of nasal symptoms and a decrease of nasal inspiratory peak flow after the challenges. The symptoms were associated with specific serum IgE, but with IgG. Further, significant increases were found in eosinophil and neutrophil counts, and in levels of tryptase, and albumin, whereas no clear rise was recorded for eosinophil cationic protein in nasal lavage fluid. Nine subjects, who were not sensitized, but who complained of work-related nasal symptoms, and 11 subjects, who were not sensitized and had no symptoms, displayed no significant change in any of these parameters. It is concluded that the symptoms in some of the workers were caused by an IgE-mediated mast cell degranulation. followed by an inflammatory reaction, engaging eosinophil and neutrophil cells.     

Specific serum antibodies against phthalic anhydride in occupationally exposed subjects

In two plants producing alkyde and unsaturated polyester resins, the time-weighted average air level during loading of phthalic anhydride (PA) was 6.6 (1.5 to 17.4) mg/m3. In a full workday the level was 0.4 mg/m3. In 60 workers, symptoms of rhinitis and/or conjunctivitis were frequently reported, mostly by heavily exposed workers (69%). Five workers (14%) with PA-associated asthma were found. All were heavily exposed during some period. There was no difference between the exposure groups with regard to total serum level of IgE, IgG, and IgM, nor specific IgE and IgM against PA. There was a significant difference of specific IgG against PA between heavy and low exposure groups (p = 0.01). One worker with asthma had an increased specific IgE level. Subjects with symptoms did not differ from subjects without symptoms in total serum IgE, IgM, IgA, or specific IgE and IgM. However, subjects with rhinoconjunctivitis had lower total IgG than the other workers (p = 0.01). The subjects with asthma had significantly higher values for specific IgG than the asymptomatic subjects (p = 0.005). Four subjects had specific IgG antibodies of subclass 4 (IgG4). Three of these four subjects had asthma, and one had rhinitis. These findings demonstrate that specific IgG is an index of PA exposure and support the hypothesis that specific IgG4 under some circumstances, may be a pathogenetic factor in asthma.     

Serum albumins are the major site for in vivo formation of hapten-carrier protein adducts in plasma from humans and guinea-pigs exposed to type-1 allergy inducing hexahydrophthalic anhydride

BACKGROUND: Organic acid anhydrides (OAAs) are highly allergenic compounds used in the chemical industry. The OAAs probably act as haptens but the proteins that form conjugates with OAAs in vivo are still unknown. Conjugates between the anhydrides and serum albumins (SAs) have routinely been used when testing for OAA-specific antibodies. However, the use of SA as the carrier-protein in these tests has never been evaluated. OBJECTIVE: The aim of this study was to identify major and also immunologically relevant protein conjugates of a particularly sensitizing OAA, hexahydrophthalic anhydride (HHPA), in plasma. METHODS: Plasma was obtained from a HHPA-exposed worker, from a guinea-pig (GP) exposed to HHPA in an exposure chamber for 2 weeks (8 h/day, 5 days/week) and from a GP exposed once, nose-only, to tritium-labelled HHPA for 8 h. The plasma was fractionated using ion exchange chromatography and gel filtration. These fractions and also aliquots of unfractioned plasma were hydrolysed, derivatized and analysed for anhydride adduct content using gas chromatography-mass spectrometry. Further, plasma from the tritium labelled HHPA-exposed GP was separated by SDS gel electrophoresis and analysed by autoradiography. In addition, immunologically relevant proteins were identified through specific IgE and IgG immunoblottings using sera from exposed workers. RESULTS: For humans > 85% and for GPs > 74% of the HHPA-adducts coeluted with SA in plasma. Autoradiography of GP-plasma shows a single 66 kDa protein that binds HHPA. IgE immunoblotting shows a major 66 kDa and a minor 28 kDa protein which could be inhibited by HHPA-SA conjugate. IgG immunoblotting showed a major 66 kDa protein and several minor protein bands. CONCLUSION: This study shows SA to be the major protein in plasma that forms adducts in vivo with HHPA. The results also show that in an in vitro synthesized HHPA plasma protein conjugate, HHPA-specific IgE and IgG antibodies bind preferably to the SA.     

Trimellitic anhydride-induced airway syndromes: Clinical and immunologic studies

This report describes a spectrum of respiratory symptoms in workers exposed to trimellitic anhydride (TMA), a biologically reactive chemical used in the plastics industry. Fourteen workers who had worked on a unit which synthesized TMA were evaluated by clinical and immunologic methods. Respiratory syndromes induced by TMA inhalation included asthma and rhinitis of the immediate type, late onset asthma with systemic symptoms, and airway irritation. TMA was shown to couple rapidly to human serum albumin, forming an immunoreactive hapten-protein complex. The workers' immunologic reactivity to this complex could be quantitated and correlated with the three respiratory syndromes. The asthma-rhinitis syndrome was mediated by IgE antibody specific for the TMA hapten. The syndrome of late onset asthma with systemic symptoms was accompanied by elevated levels of TMA-specific IgG antibody. Rheumatoid factor in high titer was found in one worker with IgE-mediated asthma and in two workers with asthma of late onset. Lymphocyte reactivity of TMA-HSA was demonstrated in three workers representative of the three clinical syndromes. Leukocyte histamine release was demonstrated to TMA-HSA in one worker with high levels of IgE antibody specific for TMA-HSA who had severe symptoms of acute rhinitis and asthma.     

Immunologic tests of specific antibodies to organic acid anhydrides

The outcome of immunologic tests of antibodies directed against hapten conjugates of organic acid anhydrides and human serum albumin (HSA) has been studied in workers exposed to phthalic anhydride (PA), methyltetrahydrophthalic anhydride (MTHPA), hexahydrophthalic anhydride (HHPA), and methylhexahydrophthalic anhydride (MHHPA). HSA conjugates of PA, MTHPA, HHPA, MHHPA, and maleic anhydride (MA) have been prepared and used in the tests. The hapten densities (HD) of the conjugates were varied by different molar ratios of hapten and macromolecule in the preparative procedure. Skin prick reactions to MTHPA-HSA increased with rising HD over the range 6-13 mol/mol. The achieved HD was tested by spectrometric and gas chromatographic methods. In RAST of IgE antibodies MTHPA-HSA with HD six and 25 showed significantly lower bindings than conjugates with intermediate HD. There was a good correlation between skin prick tests and RAST. Of 234 workers tested [MTHPA (n = 145), and HHPA (n = 89)], 45 had a skin prick reaction greater than or equal to 50% of the histamine reaction (1 mg/ml). All but two of these were RAST positive (RAST value greater than 0.3%; 0.3% upper range in 147 controls; MTHPA, n = 63; HHPA, n = 84). Nine RAST positive workers had no obvious skin prick reaction. However, their RAST values were low (less than 0.8%). In exposed workers, the ELISA value of specific IgG antibodies to MTHPA-HSA showed optimal values when tested with the HD 13 conjugate.(ABSTRACT TRUNCATED AT 250 WORDS)     

Rose hips: a new occupational allergen

We evaluated 13 workers with respiratory symptoms apparently related to occupational exposure to powdered rose hips. Nine workers had asthma, five had rhinitis, and one worker had urticaria. Seven workers had evidence of IgE specific for rose hips based on positive skin prick tests and positive in vitro tests. Four workers with histories suggestive of asthma related to work exposure underwent bronchopulmonary challenges with rose hips, and two workers had positive challenges with greater than 20% declines in FEV1 measurements. We conclude that rose hips are occupational allergens capable of producing asthma.     

Occupational Asthma Induced by the Reactive Dye Synozol Red-K 3BS

Various reactive dyes can elicit occupational asthma in exposed textile industry workers. To date, there has been no report of occupational asthma caused by the red dye Synozol Red-K 3BS (Red-K). Here, we report a 38-year-old male textile worker with occupational asthma and rhinitis induced by inhalation of Red-K. He showed positive responses to Red-K extract on skin-prick testing and serum specific IgE antibodies to Red-K-human serum albumin conjugate were detected using an enzyme-linked immunosorbent assay. A bronchoprovocation test with Red-K extract resulted in significant bronchoconstriction. These findings suggest that the inhalation of the reactive dye Red-K can induce IgE-mediated occupational asthma and rhinitis in exposed workers.     

Occupational asthma and specific IgE to a diazonium salt intermediate used in the polymer industry

This study describes sensitization to a diazonium salt intermediate, diazonium tetrafluoroborate (DTFB), produced during the manufacture of a fluorine polymer precursor. Most of the workers exposed to DTFB powder complained of respiratory and mucosal irritation. However, some of these individuals had symptoms typical of occupational asthma. Clinical and immunologic studies, including bronchial provocation testing and specific IgE measurements, were performed on two individuals with asthmatic symptoms associated with exposure to DTFB. These studies confirmed a diagnosis of occupational asthma. In an investigation of 43 other exposed workers in two separate factories handling the diazonium compound, specific IgE antibodies to DTFB-human serum albumin conjugate were found in 20% of individuals. There was a good correlation between specific IgE and exposure-related respiratory symptoms, which suggests an IgE-mediated pathogenesis. DTFB-human serum albumin conjugates were characterized by electrophoretic techniques, and it was found that conjugates prepared at pH 10 elicited optimum IgE binding in RAST. In vitro cross-linking of albumin by DTFB was demonstrated but had no effect on RAST binding. Our findings on the effect of pH and polymerization on IgE binding support proposed mechanisms for in vivo conjugation and provide information on the antigenic determinants important in IgE recognition of hapten-carrier protein conjugates.     

Pulmonary and immunologic evaluation of foundry workers exposed to methylene diphenyldiisocyanate (MDI)

A cross-sectional evaluation was performed of workers in a steel foundry in which methylene diphenyldiisocyanate (MDI) was used as a component of a binder system used to make cores and molds. Preshift and postshift spirometry and clinical evaluations were performed on 26 currently exposed (group I), on six formerly exposed (group II), and on 14 nonexposed workers to MDI (group III). Serum samples were assayed for total antibody binding, specific IgG by ELISA, and specific IgE by the RAST method to MDI-human serum albumin (HSA). Symptoms compatible with occupational asthma were elicited from seven (27%) of 26 group I workers and from three of six group II workers. No symptoms were reported by group III workers. Intrashift change in FEV1 (a mean decrease of 0.049 L) in group I workers was significantly decreased compared to that in unexposed group III workers (a mean increase of 65 ml; p = 0.043). Specific IgG and total antibody responses to MDI-HSA were detected only in workers with current or former exposure to MDI. Only one worker was identified with IgE-mediated occupational asthma exhibiting a positive prick test and elevated RAST to MDI-HSA of 25.5% bound. In this occupational setting, polyclonal immune responses to MDI-HSA and clinical sensitization to MDI were demonstrated to occur.     

A Study of Serum Antibody Activity in Workers with Occupational Exposure to Diphenylmethane Diisocyanate

The prevalence of sensitization was studied in a group of 76 foundry workers with occupational exposure to diphenylmethane diisocyanate (MDI). Ten workers had clinical evidence of asthma, 40 had non-asthmatic respiratory symptoms, and 26 were asymptomatic. Specific IgE antibodies to MDI were found in two workers (2.6%) and specific IgG antibodies, in five workers (6.6%). The prevalence of IgE and IgG antibodies was higher in the 10 subjects with asthma than in the non-asthmatic group. The prevalence of anti-paratolyl-monoisocyanate antibodies was not significantly different from that of anti-MDI antibodies, and both haptenic determinants displayed a high degree of cross-reactivity in the RAST inhibition test. The role of humoral immunological mechanisms in MDI-induced asthma is unclear in view of the rather low prevalence of these serum antibodies in this group of workers.     

IgG antibodies against polyisocyanates in car painters

A group of thirty car painters exposed to vapours and aerosols of paint containing prepolymer and monomer of hexametylene diisocyanate (HDI) was investigated. Specific antibodies against monomer HDI and prepolymerized HDI were analysed with RAST (IgE) and ELISA (IgG) assays after conjugation of the haptens with human serum albumin. There was no significant increase of serum IgG antibodies against HDI monomer, nor of specific IgE antibodies against HDI monomer or prepolymer. Specific IgG antibodies against prepolymerized HDI were significantly increased, as compared with non-exposed referents (medians 0.11 vs 0.03 absorbance (A)). Six car painters were found to have specific IgG antibodies of subclass 4 against HDI prepolymer, four also against HDI monomer. This shows an association between exposure and specific IgG antibodies. Thirteen subjects had suffered symptoms of rhinitis and/or conjunctivitis, and ten had symptoms from the bronchi (two asthma). There was no significant association between symptoms and levels of specific antibodies. Most of the symptoms were slight and unspecific, probably due to irritative effects of the exposure.     

Allergic rhinitis in Rosa domescena cultivators: a novel type of occupational allergy?

After the diagnosis of allergic rhinitis due to Rosa domescena was suspected in one subject with skin prick and nasal provocation tests, we recruited all other workers employed in rose cultivation in Yaka?ren village, Isparta. From May 2000 to July 2000 (exposure period 'time of rose handling'), we studied 600 individuals employed in rose cultivation. A questionnaire was administered by a physician, and skin testing was done by a nurse on 75 individuals suffering from asthma and/or rhinitis. Sera from these 75 subjects were available for immunologic testing. The diagnosis of atopy against rose was based on the presence of work-related symptoms, positive skin prick test (SPT) with rose extracts, and positive RAST. While no subject reported asthmatic symptoms, twenty of them reported either rhino-conjunctivitis, rhinitis or both on exposure to Rosa domescena. Fourteen of these subjects had increased specific IgE levels to Rosa domescena. Eleven (78.5%) also had a positive skin reaction to Rosa domescena. Out of the six negative sera with normal specific IgE levels to rose, only two (33.3%) had positive skin reactivity. No subject had significant daily peak expiratoy flow rate (PEFR) variations. We conclude that exposure to Rosa domescena may represent a risk for allergic rhinitis. The possibility of an occupational rose allergy should therefore be taken into consideration in the subjects working in rose cultivation.     

Occupational asthma and rhinitis related to laboratory rats: serum IgG and IgE antibodies to the rat urinary allergen

Allergic reactions to rat urinary proteins are an important cause of occupational asthma and rhinitis among laboratory workers. We have measured IgG and IgE antibodies to a purified rat urinary allergen in sera from 179 laboratory workers of whom 30 reported symptoms on exposure to rats. There was a very good correlation between IgE antibodies and positive skin tests. In addition, there was a close correlation between reported asthmatic reactions and serum IgE antibody to rat allergen: IgE ab was present in 12/18 of workers with asthmatic reactions but in only 2/135 of workers without symptoms (p less than 0.001). Serum IgG antibodies to rat allergen were present in all sera with IgE antibody but were also present in 30% of asymptomatic individuals. The incidence and quantity of IgG antibody correlated with the degree of exposure to animals (i.e., hours per day) but not with the length of exposure in years. Our results on rat allergy confirm that there is an increased incidence of asthma among individuals who were atopic as judged by positive skin tests to other allergens. However, this relationship did not apply to individuals with rhinitis alone, and excluding atopic individuals from employment would have been a very inefficient method of reducing asthma or rhinitis in this group. Our results confirm that IgE antibody responses to rat urinary allergen are an important cause of occupational disease. The results for IgG antibody suggest that their prevalence represents a marker for the degree of exposure to rat proteins.     

Immunoglobulin E-mediated asthma and hypersensitivity pneumonitis with precipitating anti-hapten antibodies due to diphenylmethane diisocyanate (MDI) exposure

Two workers are presented who were exposed to diphenylmethane diisocyanate (MDI) while coating pipes with a polyurethane foam. After a latent period of exposure, worker A developed immediate-onset asthma and worker B developed a clinical picture of hypersensitivity pneumonitis for which he was hospitalized. The antibody response of these workers to a conjugate of MDI with human serum albumin (MDI-HSA) was measured by gel precipitation, total antibody binding of 125I MDI-HSA, and specific IgG and IgE antibody by polystyrene-tube radioimmunoassay (PTRAI). Worker B had precipitating antibody to MDI-HSA by double immunodiffusion in gel. Both workers had high levels of IgG antibody specific for MDI-HSA which had some cross-reactivity with a conjugate or toluene diisocyanate and HSA. Total serum antibody binding of 125I MDI-HSA was 15 microgram/ml in worker A and 900 microgram/ml in worker B. Both workers had serum IgE antibody specific for MDI-HSA as measured by two PTRIA techniques. These results indicate that a marked immunologic response to MDI is possible in exposed workers and that hypersensitivity pneumonitis can occur subsequent to the inhalation of a low-molecular-weight chemical in the industrail setting.     

Clinical and immunologic findings of methylene diphenyl diisocyanate-induced occupational asthma in a car upholstery factory

Background Although methylene diphenyl diisocyanate (MDI) is widely used in many industries, there have been few immunological studies of MDI‐induced occupational asthma. Objectives We investigated the effects of MDI exposure on the clinical and immunologic condition of workers in a single car upholstery factory. Methods Fifty‐eight MDI‐exposed workers were studied. Work‐related lower‐respiratory symptoms (WRRS) were identified using a questionnaire. Serum‐specific IgE and IgG antibodies to MDI‐human serum albumin conjugate were detected by ELISA. Atopy was evaluated using a skin prick test. MDI‐induced occupational asthma was confirmed in the symptomatic workers with a positive result on an MDI‐specific inhalation test. Results Thirteen (22.4%) of the subjects complained of WRRS. MDI‐induced occupational asthma was confirmed in five (8.6%) of the workers, and occupational eosinophilic bronchitis was confirmed in two (3.5%). The prevalence of specific IgG antibodies (20.7%) was higher than that of specific IgE antibodies (8.6%). The prevalence of MDI‐induced occupational asthma/eosinophilic bronchitis was strongly associated with the presence of both WRRS and serum‐specific IgG antibodies to an MDI‐human serum albumin conjugate (P<0.01, <0.05, respectively). Conclusion These findings suggest that MDI could be a causative agent of occupational asthma among MDI‐exposed workers. The prevalence of MDI‐induced occupational asthma was 8.6%, and MDI‐induced eosinophilic bronchitis was confirmed in two workers. The presence of work‐related lower‐respiratory symptoms and serum‐specific IgG antibodies to an MDI‐human serum albumin conjugate may be used to predict MDI‐induced occupational asthma/eosinophilic bronchitis in MDI‐exposed workers.     

Clinical and immunological evaluation of isocyanate-exposed workers.

Isocyanates are the most significant cause of occupational asthma in our country. To evaluate the prevalence of work-related respiratory symptoms and immunologic sensitization to it, we performed a questionnaire survey, allergy skin test, radioallergosorbent test (RAST) to toluene diisocyanate (TDI)-human serum albumin (HSA) conjugate and methacholine bronchial challenge test on 23 isocyanate-exposed employees and 9 unexposed controls working in a zipper factory. Six employees (26.1%) complained of work-related respiratory symptoms and three symptomatic workers showed significant bronchoconstrictions on TDI-bronchoprovocation test. Three (13%) asymptomatic workers had high specific IgE antibodies to TDI-HSA and none of the TDI-sensitive asthmatic workers had specific IgE antibody. One of the TDI-sensitive asthmatic workers showed a negative result on the initial methacholine bronchial challenge test, but bronchial hyperresponsiveness developed after the TDI challenge. It was suggested that TDI-sensitive asthma was noted in three (13%) of 23 exposed workers and that asymptomatic workers could have high specific IgE antibody. Measurement of the changes in bronchial hyperresponsiveness after the TDI challenge could be helpful to diagnose TDI-sensitive asthma.     

Occupational asthma in poultry workers

Sixteen poultry workers with poultry house--related rhinitis and/or asthma underwent clinical and laboratory evaluation that included history and physical examination, skin tests with common inhalant and PAg, total- and specific-IgE levels, and pulmonary-function studies. Sixteen age- and sex-matched atopic subjects who were not occupationally exposed to poultry and 12 asymptomatic veterinarians with occupational exposure to poultry served as controls. Rhinitis and asthma developed only in symptomatic poultry workers after exposure to poultry; only in these individuals could immediate wheal-and-flare reactions to poultry antigens be detected (p less than 0.001). The elapsed time between the initial poultry exposure and the onset of poultry house--related symptoms averaged 10 yr. In the symptomatic poultry workers, immediate skin test reactivity and RAST reactions were most frequently associated with NFM. The association between respiratory symptoms temporally related to poultry house exposure and the demonstrable IgE antibody-mediated reaction suggests a relationship between the two.     

Occupational asthma and IgE antibodies to reactive dyes

Reactive dyes have been widely used in recent years. This paper reports nine cases of immediate type occupational asthma to reactive dyes in one dye industry. All patients had had asthmatic symptoms, four had had rhinitis and they had worked for 6 to 25 months. Skin prick tests with reactive dyes were positive and bronchoprovocation tests also produced immediate or dual types of bronchoconstriction. We used the radioallergosorbent test (RAST) technique with nitrocellulose filter paper as a solid phase to detect specific IgE to four reactive dye-human serum albumin conjugates. High specific IgE binding was found in eight asthmatic workers compared with 13 negative controls. The RAST inhibition test revealed that there was no immunological cross-reactivity between 4 reactive dyes. These results suggested that the mechanism of their asthmatic symptoms was immunological, mostly an IgE-mediate reaction.     

Symptoms and immunologic markers induced by exposure to methyltetrahydrophthalic anhydride

A study was performed in 43 workers exposed to methyltetrahydrophthalic anhydride (MTHPA) used as a hardener in an epoxy resin system. Ten workers sensitized to MTHPA (group SS; presence of serum IgE antibodies against a conjugate of MTHPA and human serum albumin (HSA) detected by RAST) had significantly higher levels of tryptase in nasal lavage fluid than 19 nonsensitized workers with work-related nasal symptoms (group NS) and 14 nonsensitized workers without nasal symptoms (group NN). This suggests an ongoing mast-cell-mediated reaction in the sensitized group. No statistically significant differences were found in the three groups concerning eosinophil cationic protein (ECP) and TAME-activity in lavage fluid. However, there was a significant increase in serum ECP in the SS group, as compared with a group of unexposed controls. Nasal challenge with MTHPA-HSA, performed in a subsequent study in seven workers from the SS group, six from the NS group, and seven from the NN, caused a larger increase of symptom score and a more pronounced decrease in nasal inspiratory peak flow in the SS group than in the other two groups. No significant rise was recorded for tryptase and ECP in lavage fluid in any of the three groups after challenge. The combined results of the two studies indicate that specific IgE antibodies play a pathogenetic role in at least some of the cases of work-related nasal symptoms associated with MTHPA exposure.