Quantitation and new antigenic determinant specificity of antibodies induced by inhalation of trimellitic anhydride in man

Pathogenesis and disease mechanisms of occupational asthma

Occupational asthma (OA) is one of the most common forms of work-related lung disease in all industrialized nations. The clinical management of patients with OA depends on an understanding of the multifactorial pathogenetic mechanisms that can contribute to this disease. This article discusses the various immunologic and nonimmunologic mechanisms and genetic susceptibility factors that drive the inflammatory processes of OA.

Phthalic anhydride allergy: development and characterization of optimized hapten-carrier conjugates for improved diagnosis

BACKGROUND

At present the diagnosis of IgE-mediated hypersensitivity to phthalic anhydride (PA) is based on conjugates that are not characterized or standardized. The aim of this study was to develop optimized and molecularly characterized PA conjugates that can be used to improve the diagnosis of PA-allergy.

METHODS

The PA conjugates were synthesized and the number of haptens bound on a carrier protein was estimated by matrix-assisted laser desorption/ionization time of light (MALDI-TOF) mass spectrometry. The ability of conjugates to bind IgE and IgG antibodies was measured by enzyme-linked immunosorbent assay (ELISA). Reactivity of the conjugates in vivo was evaluated by skin prick testing.

RESULTS

The most active IgE-binding conjugates had a PA : HSA molar ratio of 80 : 1. In the optimal conjugates the average numbers of PA haptens per carrier molecule of human serum albumin (HSA) were 14-16. In ELISA, all 13 patients and none of the 20 controls had IgE antibodies to optimized PA conjugate. The sensitivity and specificity of the ELISA was comparable to commercial CAP RAST. PA conjugates elicited positive test results in skin prick testing showing that conjugates are immunologically active also in vivo.

CONCLUSIONS

These results indicate that optimized and molecularly characterized PA-HSA conjugates can be used both in vitro and in vivo assays to improve the diagnosis of PA allergy.

Structure-activity relationships of organic acid anhydrides as antigens in an animal model

Relationships between chemical structure and immunogenicity have been studied in 13 dicarboxylic acid anhydrides. Guinea-pigs were immunized intradermally by a single dose of 0.3 M solutions of succinic anhydride (SA), maleic anhydride (MA), methylmaleic anhydride (MMA), cis-cyclohexane-1,2-dicarboxylic anhydride (cis-HHPA), trans-cyclohexane-1,2-dicarboxylic anhydride (trans-HHPA), 4-methylcyclohexane-1,2-dicarboxylic anhydride (MHHPA), cis-1,2,3,6-tetrahydrophthalic anhydride (THPA1236), cis-3,4,5,6-tetrahydrophthalic anhydride (THPA3456), cis-3-methylcyclohex-4-ene-1,2-dicarboxylic anhydride (MTHPA34), cis-4-methylcyclohex-4-ene-1,2-dicarboxylic anhydride (MTHPA44), phthalic anhydride (PA), 4-methylphthalic anhydride (MPA), and trimellitic anhydride (TMA) in olive oil. Specific IgE, IgG, IgG1, and IgG2 antibodies against guinea-pig serum albumin conjugates of the anhydrides were determined by passive cutaneous anaphylaxis (PCA) tests and enzyme-linked immunoabsorbant assay (ELISA). Specific IgG was significantly increased in all animals, except those immunized with THPA3456 and SA, which sensitized only 3/9 and 7/9 animals, respectively. Furthermore, the specific IgG values were very low in the SA group. The titers of specific IgG1 and IgG2 were increased in the IgG-positive animals. Specific IgE was positive in all animals immunized with MA, MHHPA, MTHPA (both isomers), and MPA, and in 6/9 and 5/9 guinea pigs immunized with TMA and MMA, respectively. The IgE titers were generally very low; PCA was negative after dilutions to 1:32, or less. The results indicate a considerable variation in the sensitizing potential between different organic acid anhydrides. The most marked general effect of the chemical structure on immunogenicity was the enhancement of antibody formation when a hydrogen atom in the anhydride was substituted with a methyl group.

A novel model for human interstitial lung disease: hapten-driven lung fibrosis in rodents

A novel model is described of chronic pulmonary fibrosis in rodents. The condition is induced by a single intratracheal instillation of a well-characterized fluorescent haptenic antigen, fluorescein isothiocyanate (FITC), into non-immune animals. This results in an acute inflammatory response involving a granulocytic infiltrate, which disappears over a week and is replaced by a chronic mononuclear infiltrate in which T lymphocytes predominate. Over several months, a chronic patchy fibrosis is accompanied by a sustained mononuclear interstitial infiltrate localized at sites of persistent FITC deposition. Where no FITC is present, the lung tissues are apparently normal. An immune response is mounted, as measured by the appearance of specific anti-FITC serum antibodies. This model has relevance to the pathogenesis of some forms of human interstitial lung disease.

A clinical and immunologic study of workers with trimellitic-anhydride-induced immunologic lung disease after transfer to low exposure jobs

The objective of the study was to determine the clinical and immunologic status of trimellitic anhydride (TMA) workers who have had immunologic lung diseases and who have been moved to lower exposure jobs. Twenty-nine consecutive workers with TMA-induced immunologic lung diseases who had been moved to low exposure jobs for more than 1 yr were studied retrospectively. Pulmonary symptoms were obtained by physician-administered questionnaire. Immunologic studies were performed using radioimmunoassay. Spirometry and chest film were obtained. Workers with late asthma (LA) (n = 3), late respiratory systemic syndrome (LRSS) (n = 8), or both LRSS and asthma rhinitis (A/R) (n = 6) had improved symptoms, improved pulmonary functions, and lower total antibody against TM-HSA. Five of the 12 workers with A/R had improved symptoms, improved pulmonary functions, and lower IgE against TM-HSA, whereas seven continued to have moderate to severe symptoms, abnormal pulmonary functions, and elevated IgE against TM-HSA. There were no chest film findings in any group that were definitely attributed to TMA. Although TMA workers with LA or LRSS improve when moved to lower exposure jobs, only half of workers with A/R improve; elevated IgE against TM-HSA appears to be a marker for the subpopulation of workers with A/R that does not improve.

Isocyanate induced lung disease

A review of the pathogenesis of isocyanate induced lung disease is given with an emphasis on immunologic mechanisms of disease.

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)

The impact of allergy and immunology on our expanding industrial environment

In summary, allergists and clinical immunologists have assumed a primary role related to the diagnosis and pathophysiology of a wide range of environmental and occupational diseases associated with our increasingly industrialized environment. Prevention, rather than therapy, is the primary goal in managing many of these conditions. With all such diseases, it is most important to take into account the patient's environment and to record a thorough occupational and environmental history. The concept of environmental agents as causative factors of disease in man dates to antiquity but has assumed considerably greater significance in recent years. In this context, it should be remembered that Hippocrates and Socrates both emphasized that a good physician should strongly consider the patient's environment as an aid in diagnosis. Of equal importance was the recommendation by Bernardo Ramazzini in 1713, that, "in addition to the questions and recommendations of Hippocrates," a careful inquiry into the patient's occupation should be made.

Mechanisms of occupational airways diseases induced by exposure to organic and inorganic chemicals

Inhaled low molecular weight chemicals (LMWC) encountered in the work-place can induce airways disease. Most LMWC are irritants and if exposure levels are high enough or if there is extended exposure, can cause inflammation of the eyes, respiratory tract, and alveolar membrane without class specific antibody production or involvement of cellular mechanisms. Reflex or inflammatory bronchoconstriction may result. At lower concentrations, some of these LMWC are haptenic and induce respiratory symptoms by immune mechanisms. Dose and duration of exposure, as well as physiochemical properties of the agent and host factors, influence the effect that a given agent may have on an individual. It is important to distinguish between irritant and hypersensitivity responses for diagnostic purposes and for subsequent patient management. However, long term effects of sub-lethal exposure to primary irritants, such as SO2 or chemicals which are irritants at high concentrations but can also induce antibody formation, such as the isocyanates and acid anhydrides, are not clear.

Immunologic hemorrhagic pneumonia caused by isocyanates

The occurrence of hemoptysis, dyspnea, and bilateral pulmonary opacities progressed to respiratory failure in a 34-yr-old man. Recovery occurred with corticosteroid therapy. In the absence of evidence for an infectious etiology, the possibility of immunologic trimellitic anhydride (TMA) hemorrhagic pneumonitis was considered when the lung biopsy excluded Goodpasture's and other diseases and because the patient was a spray painter. Serologic evaluation for antibodies against TMA was requested. Because the immunologic studies for TMA were negative, and because the patient was a spray painter, immunoassays for three isocyanates conjugated to human serum albumin (HSA) were carried out although there was no specific history of isocyanate exposure at that time. High levels of IgG and IgE antibodies were detected against hexamethylene diisocyanate (HDI)-HSA and toluene diisocyanate (TDI)-HSA. Further investigation documented exposure to spray paint that contained HDI and another isocyanate. The paint was sprayed on warm metal, and subsequently the worker developed an acute illness. Further plant studies were not possible. We propose that the pathogenesis of this case of hemorrhagic pneumonitis is immunologic because of uncontrolled exposure to HDI and TDI, is analogous to the immunologic hemorrhagic pneumonia caused by TMA, and should be considered as a possible cause of a similar acute lung disease after isocyanate exposure.

Low molecular weight chemicals, hypersensitivity, and direct toxicity: the acid anhydrides

The acid anhydrides are a group of reactive chemicals used widely in alkyd and epoxy resins. The major hazards to health are mucosal and skin irritation and sensitisation of the respiratory tract. Most occupational asthma caused by acid anhydrides appears to be immunologically mediated. Immunological mechanisms have been proposed to explain an influenza-like syndrome and pulmonary haemorrhage, but direct toxicity may also be important in the aetiology of these conditions.

Antibody response to trimellityl hemoglobin in trimellitic anhydride-induced lung injury

Sprague-Dawley rats were exposed to trimellitic anhydride by inhalation, and the antibody response to trimellityl (TM)-conjugated hemoglobin (HB) and TM rat serum albumin (RSA) was compared. Groups of rats were exposed to trimellitic anhydride by inhalation 6 hours per day for 2, 6, or 10 days at 100 micrograms/m3 and compared to a control group exposed to filtered air. The IgG antibody response to TM-HB in both serum and bronchoalveolar lavage (BAL) fluid was measured with ELISA. IgG antibody levels to TM-HB rose significantly throughout the exposure. A positive correlation was found between IgG to TM-HB in serum and BAL fluid. In addition, this response in both serum and BAL fluid correlated with the IgG antibody response to TM-RSA. Cross-inhibition studies indicated the existence of shared antigenic determinants on TM-RSA and TM-HB. The IgG antibody to both antigens was specific for new antigenic determinants and not for the TM hapten.

Longitudinal study of specific IgE and IgG antibodies in a patient sensitized to ethylene oxide through dialysis

IgE and IgG antibodies to ethylene oxide (EO) were monitored by RAST and by ELISA in serum from a patient with hypersensitivity reactions during hemodialysis. Serum samples from the patient covering a 7-year period were analyzed. The changes in titers of IgE and IgG antibodies correlated to the time of EO exposure as well as to clinical symptoms. EO-specific IgG antibodies were, however, also found in sera from hemodialysis patients without any hypersensitivity symptoms. Assay of specific IgG antibodies will only indicate whether a patient has been exposed to, and immunostimulated by, EO, whereas specific IgE antibodies appear to be clearly related to hypersensitivity symptoms. The hapten and carrier specificity of EO-induced IgE antibodies was studied. The antibodies were found to be solely hapten specific because carriers of different types could be used in RAST without changing the outcome of the test. The existence of new antigenic determinants related to the carrier could not be demonstrated.

Pulmonary interstitial fibrosis induced in hapten-immune hamsters

A model for pulmonary interstitial fibrosis (PIF) based on cell-mediated immune response is described. Animals were primed for contact hypersensitivity responses by skin painting with trinitrophenol (TNP), but instead of challenging with the antigen on the skin, animals were challenged with a single intratracheally administered dose of the immunizing hapten. Primed animals developed inflammation followed by pulmonary fibrosis, as determined by histologic examination. Furthermore, immunized animals developed an increase in hydroxyproline (as an indirect measure of collagen synthesis) that could be recovered from the lung by 7 days after an intratracheal challenge with TNP. The increase in hydroxyproline within the lung persisted through 30 days. The response was specific because little or no fibrosis or increase in collagen deposition was observed in immune animals that were challenged with an unrelated hapten (dinitrophenol). Unimmunized animals demonstrated a slight increase in hydroxyproline in the lung 7 days after challenge, but with time the collagen content of these control animals approached normal levels. These studies demonstrate that a specific cell-mediated immune response to a hapten within the lung can induce pulmonary interstitial fibrosis.

IgE antibody responses to platinum group metals: a large scale refinery survey

All 306 South African platinum refinery workers (116 white, 190 coloured) accepted for employment on grounds of absence of evidence of atopy were investigated using the skin prick test and RAST to detect sensitivity to platinum, palladium, and rhodium salts. RAST studies were made for these, together with HSA and DNP-HSA RAST. Of the 306 workers, 38 had a positive skin prick test to the platinum halide salts; of these, one gave a positive reaction to the palladium salt and six to the rhodium salt. There were no isolated positives to the rhodium and palladium halide salts. Total IgE levels were raised in 24 of the 38 (63%) platinum salt prick test positive workers compared with only 43 of the 268 (16%) prick test negative group (p less than 0.001). Positive RASTs were obtained in 62% of those with positive skin tests to the platinum salts. Four of the six giving positive rhodium salt skin tests gave a positive RAST to rhodium salt. Of these, two gave positive RASTS to HSA and all four to DNP-HSA. The palladium salt RAST was negative in the single skin test reactor. In the platinum salt skin test positive group a raised HSA RAST was obtained in 10.5% compared with only 2.5% in the skin negative group. Twenty one per cent of the platinum salt skin positive group had a raised RAST score to DNP-HSA with only 3.5% (4/116) in the skin test negative group, of whom three also had a raised HSA RAST. The latter findings are suggestive of IgE antibody production to new antigenic determinants in HSA produced by conjugation with the platinum salts.

A common pathway for chemical-induced tissue injury and immune responses leading to hypersensitivity and/or carcinogenesis

A common requirement for chemical-induced allergy, carcinogenesis and certain forms of liver injury appears to be the ability of the chemical to react with protein and/or nucleic acid to form covalent conjugates. Tests to detect immune responses to such conjugates can provide useful information concerning the propensity of an individual to convert normally innocuous chemicals to immuno-reactive forms under physiological conditions and may provide an indicator of the risk for developing one of the above disorders. They will enable offending substances and their active metabolites to be identified, the status of diseases which they induce determined, and the degree to which exposure has been avoided monitored. Very few studies have been published relating to this important problem. Implications of this approach are discussed.

Concentration-dependent immunologic response to toluene diisocyanate (TDI) following inhalation exposure

Little is known concerning industrial exposure conditions which lead to development of allergic sensitivity in exposed workers. This study investigated the relationship between exposure concentration and the induction of antibodies and sensitivity in a guinea pig animal model for inhalation exposure to isocyanates (Karol et al., Toxicol. Appl. Pharmacol. 53, 260-270, 1980). Groups of guinea pigs were exposed, via inhalation, to TDI concentrations ranging from 0.12 to 10 ppm. Exposure was for 3 hr/day on 5 consecutive days. Beginning on Day 22, animals were evaluated for TDI-specific antibodies, skin sensitivity, and pulmonary sensitivity to TDI. No antibodies were detected in animals exposed to 0.12 ppm TDI, whereas 55% of animals exposed to 0.36 ppm TDI or greater displayed TDI-specific antibodies in their sera. Exposure to higher TDI concentrations resulted in both a greater percentage of animals producing antibodies and higher antibody titers. Pulmonary sensitivity, assessed by bronchial provocation challenge with TDI-protein antigen, was not detected in animals exposed to 0.12 ppm TDI but was present in guinea pigs exposed to TDI concentrations of 0.36 ppm or greater. However, exposure concentrations higher than 2 ppm were pneumotoxic and resulted in few pulmonary hypersensitivity reactions. Exposure of animals to 0.02 ppm TDI for 15 weeks did not result in either dermal sensitivity, pulmonary sensitivity, or production of TDI-specific antibody. The exposure protocol, as well as the exposure concentration, was important for establishment of sensitivity. Recognition of the concentration-response relationship governing immune reaction to inhaled TDI should permit establishment of safe airborne exposure levels for industrial workers to prevent sensitization.

Clinical and immunologic correlations in trimellitic anhydride airway syndromes

Twenty workers exposed to trimellitic anhydride (TMA) powder were evaluated to correlate respiratory symptoms with total antibody activity against trimellityl human serum albumin (TM-HSA). Further, specific IgG, IgA, and IgE against TM-HSA were compared to total specific antibody levels against that antigen. The workers were categorized clinically as having either the late respiratory systemic syndrome (LRSS), immediate rhinitis and asthma, or an irritant reaction. There were no histories compatible with the pulmonary disease--anemia syndrome. Total antibody and IgG antibody activity to TM-HSA correlated well (R8 = 0.75, p less than 0.05). Total antibody activity was found in almost all TMA-exposed workers, it did not discriminate the symptomatic workers from asymptomatic workers as well as did the IgG or total antibody determinations. IgE antibody activity against TM-HSA was elevated in one worker with immediate-type asthma. Previous studies correlated symptoms caused by TMA inhalation with antibody activity. This study indicates that clinical assessment plus total antibody determination or IgG antibody and IgE antibody determination should establish a means of diagnosis of the presence or absence of immunologic respiratory disease caused by TMA powder.