Exposure to phthalates in house dust and associated allergies in children aged 6-12years

Phthalates are widely used as plasticizers in household products. Several studies have reported an association between phthalate exposure and an increased risk of allergies. The present study estimated phthalate exposure in children aged 6-12years and assessed potential correlations with allergies. House dust samples were collected from floors and multi-surface objects >35cm above the floor. Urine samples were collected from the first morning void of the day. Daily phthalate intake (DI_dust and DI) was estimated using both house dust and urinary metabolite concentrations. Exposure to di-2-ethylhexyl phthalate (DEHP) in floor dust was associated with parental-reported rhino-conjunctivitis. After stratification by gender, this trend was found to only occur in boys. Furthermore, urinary mono-isobutyl phthalate was inversely associated with parental-reported wheeze in boys. DI_dust of benzyl butyl phthalate (BBzP) and DEHP were significantly correlated with DI_BBzP and DI_DEHP, respectively. These correlations were stronger with floor than with multi-surface dust. Our results suggest that, among Japanese children, house dust from low surfaces, such as living room floors, might play a meaningful role in the indoor environmental exposure pathway for BBzP and DEHP.

Effects of phthalate esters on the sensitization phase of contact hypersensitivity induced by fluorescein isothiocyanate

BACKGROUND

Many different types of phthalate ester are used as plasticizers and are thus found in the air. There have been several studies that suggest an association between allergies and phthalate esters. We previously found that di-butyl phthalate (DBP) has an adjuvant effect in a mouse contact hypersensitivity model, in which fluorescein isothiocyanate (FITC) is involved as an immunogenic hapten.

OBJECTIVE

We examined whether other phthalate esters enhance the process of sensitization to FITC by facilitating the trafficking of FITC-presenting dendritic cells or macrophages from skin sites to draining lymph nodes.

METHODS

Mice were epicutaneously sensitized with FITC dissolved in acetone containing a phthalate ester. Sensitization was evaluated as ear swelling after a challenge with FITC. Draining lymph node cells obtained 24 h after skin sensitization were examined for FITC fluorescence by means of flow cytometry. FITC-positive cells were characterized with anti-CD11c and anti-CD11b by three-colour flow cytometry.

RESULTS

When mice were sensitized with FITC in acetone containing DBP or di-n-propyl phthalate (DPP), strong enhancement of the ear-swelling response was observed. Di-methyl phthalate (DMP) and di-ethyl phthalate (DEP) were less effective but produced some enhancement. Consistent enhancement was not observed with di-(2-ethylhexyl) phthalate or di-isononyl phthalate. Upon sensitization in the presence of DBP or DPP, the number of FITC-positive dendritic cells (total CD11c+ as well as CD11c+/CD11b+) was increased in draining lymph nodes. As to the other four phthalate esters, there was no significant increase in the FITC-positive cell number in the draining lymph nodes.

CONCLUSION

During the process of sensitization to FITC, DBP, and DPP exert strong adjuvant effects that are associated with enhancement of trafficking of antigen-presenting dendritic cells from the skin to draining lymph nodes.

[Study of dicyclohexyl phthalate on preparation and characterization of artificial antigen]

OBJECTIVE

To study the preparation and characterization of hapten and artificial antigen of dicyclohexyl phthalate.

METHODS

A dicyclohexyl phthalate hapten (4-amino dicyclohexyl phthalate) was synthesized by introducing amino as a substituent on the aromatic ring and retaining the ester group, and characterized by 1HNMR, IR and UV. The hapten was conjugated to BSA via amino diazotization linkage.

RESULTS

Lambda1 = 214nm, lambda2 = 256nm for the UV of dicyclohexyl 4-nitrophthalate and lambda1 = 226nm, lambda2 = 288nm for the UV of dicyclohexyl 4-aminophthalate. Artificial antigen was prepared and tested by fluorescence, and lambda(ex) = 307nm, lambda(em) = 468nm, and the approximate molar ratio of dicyclohexyl 4-aminophthalate to BSA was 19. The product was used as an immunogen, demonstrating that it is suitable for polyclonal antibody production.

CONCLUSION

It is a good method for preparation of artificial antigen of dicyclohexyl phthalate by introducing amino as a substituent on the aromatic ring and retaining the ester group. It was suggested that could supply excellent immune antigen for further preparation of antibody and immunoassay to dicyclohexyl phthalate.

Autoreactive responses to an environmental factor. 2. Phthalate-induced anti-DNA specificity is downregulated by autoreactive cytotoxic T cells

An environmental factor (phthalate) was shown, in our previous study, to induce serum anti-DNA responses in BALB/c, NZB and lupus-prone NZB/W F1 mice. Out of such anti-phthalate responses, cross-reactive populations were identified that strongly bind phthalate, DNA, or both. A phthalate-specific BALB/c monoclonal antibody, 2C3-Ig (gamma1,kappa), showed considerable affinity for DNA and had extensive sequence homology with the heavy and light chain variable regions of a known anti-DNA immunoglobulin, BV04-01, from lupus-prone NZB/W F1 mice. This study was initiated to address how BALB/c mice, but not NZB/W F1 mice, are protected from these adverse autoreactive B cells. Using 2C3 hybridoma cells as the prototype autoreactive BALB/c B cell, we determined whether its DNA-binding monoclonal antibody would induce any regulatory cell-mediated immune responses. Synthetic idiopeptides corresponding to the heavy and light chain variable regions of 2C3-Ig were found to be effective at inducing specific effector cells in BALB/c mice, but not in lupus-prone F1 mice. The splenocytes from BALB/c mice incubated in vitro with the idiopeptides, particularly the complementarity-determining region 1 (VL1) of the 2C3-Ig light chain, showed significant proliferative and cytolytic responses. A CD8+ cytotoxic T-lymphocyte (CTL) response was elicited that recognized the VL1 peptide presented by the Kd allele, and affected the growth of 2C3 cells. In vivo depletion of CD8+ T cells in BALB/c mice significantly decreased this CTL activity but increased the anti-DNA humoral response. These results suggest that autoreactive CTLs are induced in non-autoimmune prone mice as a mechanism to downregulate self-reactive B cells.

Autoreactive responses to an environmental factor: 1. phthalate induces antibodies exhibiting anti-DNA specificity

Environmental factors have been implicated in the induction of autoimmune disorders. We report here that a common chemical, phthalate, used widely in synthetic polymers and cosmetics induces serum anti-self DNA antibodies in BALB/c, NZB and autoimmune-prone NZB/W F1 mice. The latter group experiences a high mortality, and significantly higher anti-DNA antibody levels along with nephritis and other histopathologic changes in kidney. Comparison of amino acid sequences of an anti-phthalate BALB/c B-cell hybrid, 2C3 with the known database at the National Center for Biotechnology Information reveals a striking homology between the variable regions of 2C3-Ig (gamma1, kappa) and an anti-DNA antibody, BV04-01 (gamma2b,kappa) isolated from the lupus-prone NZB/W F1 mice. The homology is 98% for kappa light chain and 70% for gamma heavy chain. Like 2C3-Ig, BV04-01 also has specificity for d(pT)4. Furthermore, the light chains of both 2C3-Ig and BV04-01 are products of Vkappa1 gene. To understand the nature of anti-phthalate responses in general, hybridomas generated from phthalate-keyhole limpet haemocyanin-primed BALB/c splenocytes were characterized. The study identifies cross-reactive populations that strongly bind phthalate, DNA, or both. Of the 14 hybridomas evaluated, six express the same Vkappa1 gene-derived light chain as 2C3, and bind both phthalate and ds and ss-DNA. They specifically recognize the oligonucleotides, d(pT)4, and d(pT)10. Additionally, when antisera raised against idiopeptides corresponding to 2C3-Ig hypervariable regions are allowed to react with 2C3-Ig, their binding is blocked specifically by both d(pT)4 and phthalate. This study clearly demonstrates that phthalate exposure leads to activation of a significant number of autoreactive B-cells, with the consequence of a significant pathogenic progression in susceptible NZB/W F1 mice but not in non-autoimmune-prone BALB/c.

Investigation of the adjuvant and immuno-suppressive effects of benzyl butyl phthalate, phthalic acid and benzyl alcohol in a murine injection model

In a recent study, di-(2-ethylhexyl) phthalate (DEHP) and its metabolite, mono-2-ethylhexyl phthalate, were shown to possess adjuvant effect [Toxicology 169 (2001) 37; Toxicology Letters 125 (2001) 11]. The present study investigates the adjuvant effect of another important commercial phthalate plasticizer, benzyl butyl phthalate (BBP) as well as its degradation products, phthalic acid and benzyl alcohol (BA) in a murine model. The model antigen, ovalbumin (OA), was injected either alone (OA control group), together with one of the test substances (test group) or together with aluminium hydroxide, which served as the positive adjuvant control. The mice were boosted either once or twice with OA before blood was collected and assayed for the content of OA-specific IgE, IgG1 and IgG2a antibodies by ELISA methods. Adjuvant effect was defined as a statistically significant increased antibody level in the test groups compared with the OA control group. Conversely, if the antibody production in a test group was significantly lower than the OA control group, it was deemed to be immunosuppression. This study demonstrated that BBP, in contrast to DEHP, did not possess adjuvant effect. Furthermore, immunosuppression was apparent in the case of BA. The study also demonstrated that if the injections give rise to formation of wounds, it may cause false positive results.

In vitro effects of monophthalates on cytokine expression in the monocytic cell line THP-1 and in peripheral blood mononuclear cells from allergic and non-allergic donors

It has recently been shown that plasticizers are present in indoor air dust, which may lead to human exposure via the inhalation route. Moreover, studies have indicated that plasticizers may possess adjuvant effects increasing the health damaging potential of allergens. The aim of this study was to investigate the in vitro effect of metabolites of phthalate plastisizers, such as whether an adjuvant effect is paralleled by changes of the cytokine expression in the monocytic cell line THP-1 and in peripheral blood mononuclear cells (PBMCs) from allergics and non-allergics. The toxicity monitored by cell viability was determined by incubating THP-1 cells with a 10-fold dilution series of monophthalates for 24 h. At different points in time cytokine expression (IL-1beta, IL-6, IL-12alpha (p35)) in THP-1 cells incubated with non-toxic concentrations of monophthalate (2-20 microg/ml)+/-LPS (1 microg/ml) were determined using Quantitative Competitive RT-PCR. PBMCs from allergics and non-allergics were incubated with monophthalate 220 microg/ml) for up to 48 h and cytokine expression (IL-4, IL-5, IFN-gamma) was measured using real-time PCR. The cytotoxic level of monophthalates is 20-200 microg/ml, depending on the individual monophthalate. There seems to be a correlation between increasing side-chain length and toxicity. Monophthalates did not induce changes in cytokine expression in THP-1 cells, though there is an increase when co-incubating with LPS. Cytokine expression in PBMC seems virtually unchanged when co-incubated with monophthalate, though mono-n-butyl phthalate (MBUP) tends to increase the level of IL-4 in PBMCs from allergic individuals. The two cellular models demonstrated the dynamics of regulated cytokine mRNA and are applicable for in vitro immunotoxicological investigations. The results regarding monophthalates suggest these to have a limited effect on cytokine expression in the monocytic cell line THP-1 and weak effect on cytokine expression in PBMCs from allergic and non-allergic individuals.

Adjuvant and immuno-suppressive effect of six monophthalates in a subcutaneous injection model with BALB/c mice

The prevalence of allergic airway diseases is rapidly increasing in Western Europe and North America. This increase in disease prevalence may be associated with environmental pollutants. The present study investigated the adjuvant and immuno-suppressive effect of a series of monophthalates which are considered to be important metabolites of commonly used phthalate plasticizers. The effects were studied in a screening model. Ovalbumin (OA), used as the model antigen, was injected subcutaneously in the neck region of BALB/cJ mice with or without one of the test substances, mono-n-butyl phthalate (MnBP), monobenzyl phthalate (MBnP), mono-n-octyl phthalate (MnOP), mono-2-ethylhexyl phthalate (MEHP), mono-iso-nonyl phthalate (MiNP) or mono-iso-decyl phthalate (MiDP). The levels of OA-specific IgE, IgG1 and IgG2a in sera were measured by ELISA. Immuno-suppressive effect, defined as a statistically significant reduction in IgE or IgG1 antibody production, was observed with MEHP (1000 microg/ml, IgE and IgG1), MnOP (1000 microg/ml, IgE and IgG1), MiNP (1000 microg/ml, IgE and 10 microg/ml, IgG1) and MiDP (100 microg/ml, IgE and IgG1). Adjuvant effect, defined as a statistically significant increase in IgE or IgG1 antibody level, occurred with MEHP (10 microg/ml, IgE), MnOP (100 microg/ml, and 10 microg/ml, IgG1) and MiNP (100 microg/ml, IgE). No statistically significant immune modulating effect was seen with MBnP and MnBP.

Allelic differences in the VHOx-1 gene explain the absence of a B cell clonal dominance in the primary response of C57BL/6 mice to phthalate

A highly conserved Id (CRIXmp-1) associated with the murine (BALB/c) humoral immune response to the hapten phthalate (Xmp) is conspicuously absent in C57BL/6 mice. The absence of this Id in C57BL/6 mice is shown here to be due to the absence of the appropriate VH gene (VHOx-1) usage in the Xmp response. To determine whether the failure to utilize this VH was due to an active suppression or to the lack of the requisite VH gene in the available repertoire, VHOx-1 gene-specific primers were used to amplify the germ-line VHOx-1 gene from genomic DNA from BALB/c and C57BL/6 mice. The germ-line coding sequence of the C57BL/6 allele of the VHOx-1 gene is 99% similar to the germ-line coding sequence of the BALB/c allele. Amplification of cDNA made from splenic RNA from C57BL/6 mice confirmed that this gene is expressed. There are four nucleotide differences that lead to three amino acid changes in the predicted protein sequence. Each change is either in or immediately adjacent to a complementarity-determining region (CDR). Two of these changes are unique to the C57BL/6 allele and are not shared with CRIXmp-1-expressing strains. These two changes are predicted to alter the Xmp binding capabilities of the C57BL/6 allelic form of this VH gene, thereby explaining the absence of the Xmp-1 clonotype, which is dominant in the primary Xmp immune response of most other strains of mice.

Transient dominance of the early primary immune response by a highly conserved B-cell clone that is distinguished by its lack of memory, high threshold of activation, and a high affinity

We establish here that the very early primary response to the hapten phthalate (Xmp) is distinguished by a restricted heterogeneity with over 80% of the anti-Xmp antibodies expressing a single well-defined cross-reactive idiotype (CRIXmp-1) associated with a previously described highly conserved clonotype that is expressed by most inbred strains of mice and many outbred mouse populations as well. The characteristic early dominance of this one clonotype in the primary response is transient. While the CRIXmp-1 clonotype is present later in the primary and throughout the secondary response, it represents only a very small proportion of the total anti-Xmp antibody population at these times. The early dominance of the single clonotype is rapidly replaced by a heterogeneous population of antibodies. Differential activation thresholds for the primary response clonotype (CRIXmp-1) and secondary response clonotypes, and the failure of the dominant primary response clonotype to expand in the secondary response (i.e., absence of memory) suggest the presence of two distinct B-cell lineages.

Nucleotide sequence of messenger RNA encoding VHDJH and VKJK of a highly conserved idiotype-defined primary response anti-hapten antibody

The primary humoral immune response of mice to the hapten phthalate (Xmp) is focused upon two adjacent immunodominant negatively charged carboxyl groups on a benzene ring that are in positions meta and para to the azolinkage (i.e., Xmp) to the protein carrier keyhole limpet hemocyanin. A significant fraction of the anti-Xmp antibodies raised in several different inbred mouse strains (BALB/c, DBA/2, A/HeHa; C3H, and SM/J), and many wild mouse populations express a cross-reactive Id, CRIXmp-1. This CRIXmp-1 is conspicuously absent in C57BL/6 mice. In order to obtain a better understanding of the events and parameters that influence the selection and regulation of the primary response B cell repertoire, and to explore the structural basis of Ag binding, we have determined the nucleotide sequence of the entire V region gene complexes, which encode the H and L chains of these highly conserved and dominant CRIXmp-1+ antibodies. Our data establish that the H chain gene complex consists of a single VH germ-line gene that is identical to VH Oxazolone-1, encoding the H chain of another highly conserved and dominant cross-reactive Id family associated with the primary response to Oxazolone. In CRIXmp-1+ Xmp-specific hybridomas this gene is joined to a limited set of D region sequences that express a conserved amino acid motif-GLR. At least three of the five D regions examined are coded for by DFL16.2. This VHD complex can be utilized with one of three different JH region genes (JH1, JH2, and JH4) without any significant effect upon antibody fine specificity or Id. In spite of this lack of JH fidelity all of the CRIXmp-1+ hybridomas have precisely maintained the same length in the H chain CDR3 and FRW4 by altering either the length of the D segment or the length of JH. Nucleotide sequence analysis of the VL gene complex of CRIXmp-1+ anti-Xmp antibodies indicates that the L chain V region is also encoded by a single germ-line gene. The amino acid sequence predicted from the nucleotide sequence of the VKJK from Xmp-specific CRIXmp-1+ hybridomas is identical to the sequence of the anti-arsonate antibody 1210.7, which is the prototype of another Id family (CRI) that is conserved and dominant in BALB/c mice.

The production of a bispecific anti-CEA, anti-hapten (4-amino-phthalate) hybrid-hybridoma

A standard hybridoma fusion technique was used to produce a monoclonal antibody capable of binding both carcinoembryonic antigen (CEA) and the hapten 4-amino-phthalate. A hypoxanthine-aminopterin-thymidine (HAT) sensitive anti-CEA hybridoma and KLH-phthalate immunized spleen cells were hybridized to yield clones producing bispecific monoclonal antibodies. The desired bispecific antibody was identified using both enzyme-linked immunosorbent assay (ELISA) and radio-immunoassay. The resultant hybrid-hybridoma or "tridoma" was subcloned and expanded to yield a stable population. Bifunctional antibody was then isolated from the various possible recombinants by ion exchange chromatography. This general method may be used to produce bispecific monoclonals against a wide variety of tumor associative antigens and reagents for immunodetection or treatment.

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.

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.

Sensitisation of guinea pigs by inhalation exposure to low molecular weight chemicals

Guinea pigs could be immunologically sensitised (as shown by the development of antigen-specific homocytotropic antibodies) to toluene diisocyanate by exposing them for 3 h a day for 5 consecutive days to atmospheres containing free chemical. Pulmonary reactions could be elicited in many of the sensitised animals by challenging them with atmospheres containing protein conjugates of the chemical and then measuring changes in respiratory rate. Successful elicitation of pulmonary reactions appeared to depend upon a number of factors, including the quality of the protein conjugate used for the challenge, but possibly also the development of IgE as well as IgG1 antibodies. Antigen-specific homocytotropic antibodies were detected in guinea pigs similarly exposed by inhalation to two non-isocyanate respiratory allergens, trimellitic anhydride and a reactive dye. Although the animals were immunologically sensitised to the chemicals, challenge with atmospheres containing appropriate chemical-protein conjugates failed to stimulate changes in respiratory rate.

Induction of antigen-specific bronchial reactivity to trimellityl-human serum albumin by passive transfer of serum from humans to rhesus monkeys

A rhesus monkey model was developed to demonstrate the pathogenetic role of IgE to chemical hapten-protein conjugates in causing human occupational asthma from reactive chemicals. Serum from a worker with trimellitic anhydride (TMA) asthma that contained high titers of IgE, IgG, IgM, and IgA to trimellityl-human serum albumin (TM-HSA) was aerosolized into the lungs of two monkeys to afford passive airway sensitization. After the monkeys were challenged with aerosolized TM-HSA, pulmonary functions demonstrated acute airway responses similar to that of Ascaris antigen-induced, IgE-mediated bronchospasm in Ascaris-sensitive monkeys. The monkeys had no airway reactivity when challenged with TM-HSA 1 week after the first positive TM-HSA response elicited with passive sensitization. Passive cutaneous reactivity to TM-HSA was also elicited by the donor serum, but heat-treated donor serum failed to confer cutaneous or bronchial reactivity. These results indicate that airway reactivity in this passive-transfer monkey model of TMA asthma is an antigen-specific response mediated by heat-labile serum factors, presumably IgE to TM-HSA, and does not occur by irritant mechanisms. This experimental model could become a valuable system for evaluating the role of IgE to hapten-protein conjugates in the immunopathogenesis of asthma caused by other reactive chemicals capable of acting as haptens. We postulate that immunologic and clinical features should be consistent with asthma caused by such reactive chemicals and mediated by such mechanisms.

Suppression of the murine anti-trimellityl (TM) IgE response: induction of B cell tolerance by conjugates of TM and polyvinyl alcohol

It was previously shown that administration of conjugates of trimellitic anhydride with polyvinyl alcohol (TM-PVA) could suppress the IgE anti-TM immune response of mice sensitized with a TM-ovalbumin conjugate. In the present study, the existence of TM-specific B cell tolerance was shown by cell transfer experiments in which splenic B cells from mice treated with TM-PVA failed to interact with either the helper T (Th) cells of carrier primed recipients or with Th cells derived from carrier-primed donors. In contrast to previous findings from this laboratory indicating that tolerogenic conjugates of PVA and the 2,4-dinitrophenyl group led to both B cell tolerance and activation of suppressor T (Ts) cells, no evidence was obtained for the induction of Ts cells by TM-PVA. Thus, the induction of demonstrable Ts cells by hapten-PVA conjugates may depend on some property conferred by the haptenic group.

Irritant symptoms and immunologic responses to multiple chemicals: importance of clinical and immunologic correlations

An evaluation of workers in a plant was conducted because of multiple complaints of ocular, nasal, skin and chest symptoms. Antibody activity against 4 different chemicals was identified: an aliphatic diisocyanate, 4-vinylcyclohexene dioxide, trimellitic anhydride (TMA) and an unknown chemical present in a plasticizing ester known as n-octyl-n-decyl-trimellitate. The source of TMA which resulted in immunization in the plant is unknown. The presence or absence of antibodies did not correlate with the presence or absence of symptoms and it was concluded that no occupational allergic disease was present in these workers. Antibody studies alone do not make a diagnosis of occupational allergic disease and clinical correlation is required. Immunoassays may be useful in identifying exposures to immunizing chemicals in the workplace for potential clinical correlation or for exposure monitoring in the workplace.

Expression of mu and gamma 1 membrane forms of immunoglobulin segregate in somatic cell hybrids

In the present investigation, we have utilized the somatic cell hybridization technique to generate an experimental model for studying the differential expression of membrane (mIg) and secreted (sIg) forms of immunoglobulin that characterize different stages of B cell development. We describe here that fusion of the dextran-binding myeloma, MOPC 104E (mu, lambda 1) and the phthalate-binding B cell hybridoma, 2C3E1 (gamma 1, kappa) results in the formation of antigen-specific, double hybrids (tribrids) that coexpress both parental secreted forms of Ig but express only one of the two possible membrane forms of immunoglobulin (Ig). This segregated expression of membrane Ig is a new and unexpected finding that has been substantiated here by both immunological and biochemical methods. Analysis by SDS-containing polyacrylamide gels (SDS-PAGE) reveals distinct and characteristic migration patterns for each of the four Ig heavy chains in the tribrids (mu membrane, mu secreted, gamma 1 membrane and gamma 1 secreted). Immunochemical analysis of the immunoglobulin from the tribrids confirms the coexpression of both secreted forms of immunoglobulin in most of the tribrid lines tested and indicates that about 30% of the tribrids express only phthalate-specific gamma 1 membrane Ig, while 38% express only dextran-binding mu membrane Ig. About 30% of the tribrids secrete both antibodies but express no membrane form and less than 1% are non-secretors. Approximately 2% initially express both membrane forms of Ig, as determined by immunocytoadherence assay using appropriate target cells but subsequently express only one membrane form during propagation in vitro. SDS-PAGE analysis of surface labeled tribrids confirms that in tribrids expressing membrane Ig, only a single mIg is synthesized. These results suggest that the expression of the secreted and membrane forms of immunoglobulin are separately regulated and the tribrids represent a model with which to study the mechanisms involved in the regulation of each structurally distinct immunoglobulin form.

Antibody responses to hemodialysis-related antigens in chronic hemodialysis patients

Allergic-type reactions during hemodialysis are sometimes due to sensitization to ethylene oxide. To examine the possibility that additional antigens might be a basis for unexplained reactions, antibodies to formaldehyde and phthalate-related antigens and to dialyzer extracts were measured. Unselected sera from 113 chronic hemodialysis patients (CHP) and 200 control subjects were tested for IgG antibodies to formaldehyde-treated human serum albumin (HSA). The IgG antibody activity was confirmed in sera of five CHP who had used formaldehyde-treated dialyzers. These antibodies also reacted with formaldehyde-treated red blood cells. Sera from 71 CHP and 80 controls were tested for IgE antibodies to diethylphthalate-treated HSA; antibody was detected in two CHP sera. With extracts from hollow-fiber dialyzers, IgG antibody was detected in approximately 1/3 and IgM antibodies in approximately 1/2 of CHP sera. This antibody was found in comparable numbers of control sera. It was concluded that these additional substances are immunogenic and could be involved in allergic-type reactions.

Idiotype-specific T lymphocytes responsible for the selection of somatic variants of a B cell hybrid

A B cell hybrid (2C3E1), which when cultivated in vitro stably expresses a serologically defined private idiotype on the cell surface, undergoes a somatic variation which culminates in the generation of idiotype-negative variants when propagated as a tumor in syngeneic BALB/c mice. Lyt-1+ and Lyt-2- BALB/c T cells derived from appropriately primed spleen cells when co-cultured with 2C3E1 tumor cells in vitro are responsible for the generation or selection of the idiotype-negative tumor variants. The idiotype-specific effector T cells responsible for the variant production in vitro and in vivo are triggered either by viable or irradiated 2C3E1 tumor cells, but not by soluble idiotype-positive monoclonal antibody secreted by the tumor. The idiotype-positive antibody did stimulate the production of the effector T cells when the soluble protein was covalently linked to the plasma membrane of BALB/c spleen cells, but not when the idiotype-positive protein was presented on allogeneic C57BL/6 spleen cells. A single exposure of spleen cells to 2C3E1 cells in vivo was sufficient to prime the idiotype-specific T cells, but the frequency and reproducibility of variant selection increased when the in vivo primed effector T cells were restimulated by irradiated 2C3E1 cells in vitro prior to co-cultivation with the wild-type 2C3E1 cells. The initial variant B cell lines could be segregated into several different phenotypes. However, after extensive cultivation either in vitro or after repeated transfer in vivo, all of the variant cell lines acquired a single stable phenotype that was characterized by the loss of both the surface and secreted idiotype marker and antigen-binding activity associated with the wild-type 2C3E1 cells.

A new cross-reactive idiotype-defined family in the phthalate humoral immune response of mice. I. Linkage of VH-Xmp to IgCH allotype locus and mapping with respect to other known VH genes

A cross-reactive idiotype family was previously identified from a very large library of phthalate-specific hybridoma clones. The prototype of this idiotype family is the hybridoma, 2E9, secreting an IgM antibody with phthalate specificity. A portion of both primary and secondary anti-phthalate antibodies elicited in all BALB/c mice tested expresses the 2E9 cross-reactive idiotype. This idiotype has now been found in the anti-phthalate antibodies of several other inbred strains of mice (A/HeHa, DBA/2, and C3Hf/HeHa) tested but not in C57BL/6 mice. Anti-phthalate antibodies elicited from congenic mice BC.8, which express the same IgCH allotype as BALB/c mice but possess C57BL/6 genetic background, contain the 2E9 cross-reactive idiotype, whereas this idiotype is not expressed on the anti-phthalate antibodies derived from another congenic mouse CB.20, which expresses a C57BL/6 IgCH allotype and a genetic background of the BALB/c strain. These results indicate that the gene controlling the 2E9 idiotype is closely linked to the IgCH allotype locus. The 2E9 cross-reactive idiotype was also found in all of the F1 mice (BALB/c X C57BL/6) tested, and the level of expression of this idiotype in the F1 mice was quantitatively equivalent to the allotype/idiotype homozygous mice. The expression of the 2E9 idiotype in the phthalate repertoire has been followed in 12 different wild mouse populations. As expected, the 2E9 idiotype was observed in a large proportion of the wild mouse strains. Surprisingly, several examples of nonconcordance in the expression of idiotype and allotype were observed in these mice. One likely explanation for the linkage breakdown is a crossing over of the heavy chain constant and variable region gene complexes. In the SM/J inbred strain of mice, where such a crossover has occurred, nonconcordance between allotype and 2E9 idiotype expression was demonstrated. By using the recombinant inbred BXD strains of mice, the VH gene encoding the 2E9 idiotype has been mapped with respect to other known VH gene families. Relative to other VH genes the VH-Xmp is situated very close to the IgCH gene region.

Phthalic anhydride-induced occupational asthma

Out of 118 workers exposed to phthalic anhydride (PA) dust for 2 months or more in four plants producing alkyd and/or polyunsaturated polyester resins, 28 (24%) suffered from work-related rhinitis, 13 (11%) from chronic productive bronchitis, and 21 (28%) from work-associated asthma. Asthma was generally preceded by rhinitis and was mostly of late type. 3 out of 11 asthmatics had a PA-positive skin test. In 2 subjects the presence of antibodies was demonstrated by the Prausnitz-Küstner test. 4 out of 25 heavily exposed subjects without asthma had a nonspecific bronchial hyperreactivity. The results did not indicate any significant 'healthy worker selection' as regarding rhinits and asthma. Chronic productive bronchitis was common and was more prevalent among former workers than among present employees, indicating a selection of nonreacting subjects in the plant. The time-weighted average breathing zone PA levels in two plants were between 3 and 13 mg/m3 during different direct PA handling operations and less than 0.3 mg/m3 at other kinds of work. In 2 subjects, positive bronchial provocation was obtained by short-term exposure to 0.5 and 6 mg PA/m3, respectively.

Cross-reactive idiotype family observed in the phthalate-specific B cell repertoire of adult BALB/c mice: diversity of IgM compared with IgG monoclonal anti-phthalate antibodies

A highly conserved clonotype has been identified within the repertoire of B cells specific for the negatively charged hapten phthalate. The prototype of this phthalate-specific clonotype is a primary-response hybridoma (2E9) that produces a mu,kappa anti-phthalate antibody. The 2E9 monoclonal antibody was found to share idiotypic determinants with several other independently-derived mu,kappa and gamma 1,kappa anti-phthalate monoclonal antibodies and with a significant proportion of conventional anti-phthalate antibodies derived from all of the BALB/c mice immunized with phthalate-keyhole limpet hemocyanin. Competitive RIA analysis of the 2E9 idiotypic relatedness between primary and secondary response antibodies was consistent with the hypothesis that the primary response mu,kappa antibodies represent a conserved germ-line product, whereas the secondary response to gamma 1,kappa antibodies reflect somatic variants of the 2E9 clonotype. Further analysis with a site-specific anti-idiotype reagent suggests that the idiotypic differences between mu,kappa and gamma 1,kappa monoclonal antibodies occur at positions outside of the combining site. Fine specificity analysis of the monoclonal antibodies expressing the 2E9 cross-reactive idiotype (CRI) also supports this hypothesis. Seven to 35% of the anti-phthalate antibodies after a single immunization with phthalate-KLH and 1 to 10% of the antibodies after a second immunization express the 2E9 CRI. The 2E9 CRI was also found in several other strains of mice, and its expression was associated exclusively with anti-phthalate antibodies.

Detection of IgE-mediated respiratory sensitization in workers exposed to hexahydrophthalic anhydride

Twenty-seven workers with occupational exposure to hexahydrophthalic anhydride (HHPA) from an epoxy resin molding system were studied to evaluate the nature of their reported respiratory complaints. The workers were evaluated by questionnaire, pulmonary function tests, and serologic investigations. The presence of serum-specific IgE and IgG to an HHPA-human serum albumin (HSA) conjugate was measured by use of RAST and ELISA assays. Estimates of exposure to HHPA were made for each worker on the basis of job description and environmental sampling. Seven workers reported symptoms of asthma and rhinitis; four workers had symptoms consistent with occupational asthma. Fourteen of the remaining 20 workers reported nasal or ocular symptoms while they were at work. No worker demonstrated a significant (greater than 20%) pre-to postshift decrement in FEV1. Twelve workers had significant levels of specific IgE to HHPA-HSA; 11 had elevated levels of specific IgG to HHPA-HSA. A group of workers estimated to have higher exposures to HHPA had a significantly higher mean total IgE level (p less than 0.05) and significant titers of HHPA-HSA-specific IgE or IgG, or both (p = 0.048) as compared to a group with lower exposure to the anhydride. All four workers with occupational asthma/rhinitis had significant levels of specific IgE to HHPA-HSA (ranging from 8.7% to 23.4% RAST binding); three workers did not work directly in the HHPA area but were located in nearby sections of the plant with lower exposures to HHPA. Three workers with symptoms of asthma not clearly associated with the workplace did not have significantly elevated specific IgE levels. Another radioimmunoassay with the use of beads coated with mouse monoclonal antihuman IgE was used to quantitate the amount of specific anti-HHPA-HSA binding (range 1.0 ng to 32.6 ng/ml) present in workers' sera. The solid-phase bead radioimmunoassay was inhibited by the homologous HHPA-HSA conjugate but not by HHPA hapten alone in two workers, suggesting that these workers were sensitized to new antigenic determinants. We conclude that HHPA is a potent industrial sensitizer and is capable of inducing IgE-mediated disease. Prospective investigations are required to define the incidence and severity of clinical sensitivity.

Interaction of smoking and atopy in producing specific IgE antibody against a hapten protein conjugate

A survey was carried out of a population of workers exposed to tetrachlorophthalic anhydride, an acid anhydride epoxy resin curing agent known to cause asthma. Using a radioallergosorbent test with a tetrachlorophthalic anhydride human serum albumin conjugate, specific IgE antibody was detected in serum from 24 out of 300 factory floor workers exposed to tetrachlorophthalic anhydride. Of these 24, 20 (83.3%) were current smokers compared with 133 (48.2%) of 276 without antibody (p less than 0.01), and there was a weaker association with atopy, defined by skin tests with common allergens. Smoking and atopy interacted, the prevalence of antibody being 16.1% in atopic smokers, 11.7% in non-atopic smokers, 8.3% in atopic non-smokers, and nil in non-atopic non-smokers (p less than 0.025). Smoking may predispose to, and interact with atopy in, the production of specific IgE antibody to this hapten protein conjugate.

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)

Hapten-modified basophils: a model of human immediate hypersensitivity that can be elicited by IgG antibody

Trimellitic anhydride (TMA) was incubated with human leukocytes to produce leukocytes with trimellityl (TM) haptenic determinants. The basophils in these TM leukocytes released histamine when challenged with human serum containing IgG but no IgE antibodies against TM determinants. Controls of TMA-treated cells exposed to normal human sera or untreated cells exposed to anti-TM sera released no histamine. The most relevant site of TMA modification of the basophil was receptor-bound IgE. This was demonstrated by the marked reduction in histamine release if IgE was removed from the leukocytes before TMA treatment and challenge and also by activation of release from untreated cells by passive sensitization with TM-IgE before challenge. Affinity-purified IgG from an anti-TM serum released much more histamine from TMA-treated cells than did the IgG-poor effluent at similar protein concentrations. These observations suggest a new model of hypersensitivity resulting from human exposure to chemicals capable of combining with autologous proteins. In some individuals this could result in both an immune response to the new determinants without the production of significant quantities of IgE antibodies and hapten modification of receptor-bound IgE on mast cells and basophils. After sufficient antibody was produced, reexposure to the chemical with hapten modification of mast cells or basophils or both could result in mediator release and clinical symptoms. This mechanism may be relevant to immediate-type chemical hypersensitivity reactions in which IgE antibody has not been demonstrated.

Four-year evaluation of workers exposed to trimellitic anhydride. A brief report

In a four-year clinical, immunologic, and environmental study of trimellitic anhydride (TMA) exposure in a single plant, 20 workers exposed to TMA powder were evaluated in 1979 and a total of 32 workers were evaluated from 1979 to 1983. Two distinct groups emerged before and after workplace control improvements were made in 1979. Seventeen of the original 20 workers were available for longitudinal study through 1983. Annual clinical evaluations and serum radioimmunoassays for total antibody binding and specific IgE binding to 125I TM-HSA (human serum albumin) were performed on all 32 workers. In 1979, six workers had antibody against TM-HSA, three had the late respiratory systemic syndrome, and two had TMA-induced allergic rhinitis or allergic rhinitis and asthma. One worker had antibody against TM-HSA without illness. Fifteen additional workers were evaluated longitudinally after institution of several workplace control measures. Four of these 15 workers had TMA exposure prior to environmental improvement and joined the study in 1982. The remaining 11 workers joined the study in 1982 and had at least two years of TMA exposure in the modified workplace. None of these 11 workers developed a TMA-induced immunologic syndrome or significant total or specific IgE antibody binding to 125I TM-HSA.

Suppression of the anti-trimellityl (TM) IgE response in mice by conjugates of TM with polyvinyl alcohol

The i.p. injection of 1 microgram of TM3-OA or TM9-OA with 1 mg of A1(OH)3 into B6D2F1 mice elicited the production of antibodies of the IgE and other classes to the trimellityl (TM) group and ovalbumin (OA). The induction of anti-TM antibodies belonging to the IgE and other immunoglobulin classes was specifically suppressed by the administration of tolerogenic conjugates prepared by coupling trimellitic anhydride (TMA) to the hydrophilic non-immunogenic polymer, polyvinyl alcohol (PVA), prior to immunization with TM-OA conjugates. More importantly, established anti-TM responses were also suppressed by these TM-PVA conjugates. By contrast, however, treatment with TM-PVA conjugates did not affect either the primary or the established anti-OA antibody response. The tolerogenic effects of the PVA conjugates were dose-dependent and appeared also to be dependent on the epitope density. Treatment with these conjugates also prevented immunized mice from showing any symptoms of systemic anaphylaxis on challenge with polyvalent TM-protein conjugates. These findings indicate that these conjugates may have the potential of useful therapeutic agents for the treatment of TMA-induced pulmonary hypersensitivity diseases.

A filtration double antibody radioimmunoassay that simplifies and semi-automates the isolation of immune precipitates

A semi-automation of fluid phase double antibody radioimmunoassay has been developed. The immune precipitate that was formed in 96-well microtitration plates was harvested and washed on microfibre filters using a Titertek cell harvester. A disc transfer system originally designed for use with the harvester was used as a quick and easy method of transferring the filter discs containing immune precipitate into vials for counting. The results of radioimmunoassay using the microtitration plate-filtration and conventional tube-centrifugation method are essentially identical. The microtitration plate-filtration radioimmunoassay has the following advantages over the conventional tube-centrifugation method: (1) there is no centrifugation required; (2) handling of microtitration plate is easier than the tubes in racks; and (3) it requires much less time to perform the assay.

Hapten-specific B cell repertoire probed by hybridoma technology: selection and characterization of representative clonotypes from the antibody-forming cell pool

In the course of this study, more than 3000 phthalate-specific antibody-forming cell hybrids were identified using the hybridoma technology. With the aid of a rapid screening assay and an extensive library of phthalate analogs, it was possible to assign selected hapten-specific clones to one of 11 distinct fine-specificity sets. This compartmentalization of the phthalate-specific hybridomas has made it possible to focus attention upon a single manageable portion of the phthalate-specific repertoire. Fourteen clones from a single fine-specificity set were selected for further immunochemical characterization. Five of these clones were found to secrete an antibody that was indistinguishable in isoelectric focusing. Affinity-purified, high-resolution anti-idiotype antibodies were prepared with specificity for the antibodies produced by one of these clones (i.e., 4C7). A major portion of the serologically defined private idiotype (4C7 IdI) was shown to be associated with the ligand-combining site. Our results indicate that the five clones that share a common spectrotype also express the 4C7 IdI. Two other independently derived clones from two distinct fusions also share this idiotype. The 4C7 IdI was also identified in affinity-purified anti-phthalate antibodies derived from a pool of phthalate-immune serum (conventional antibody) and from affinity-purified antibodies derived from a pool of serum from unimmunized BALB/c mice (natural antibody). The 4C7 IdI is thus considered to represent a repeating clonotype in the phthalate-specific repertoire of BALB/c mice, and will serve as one of several useful clonal markers that are being developed for studies of the mechanism regulating idiotype expression.

Immune response of dogs and rabbits to intrabronchial trimellitic anhydride

8 dogs and 7 rabbits were immunized intrabronchially with trimellitic anhydride (TMA) using three different immunizing doses. An immune response occurred in both animal species. Predominantly IgG with lower levels of IgM and IgA antibodies against trimellityl-erythrocytes (TM-E) were detected on both dogs and rabbits. Antibody binding of TM125I dog serum albumin (TM125I-DSA) occurred in most dogs and of TM125I rabbit serum albumin (TM125I-RSA) in 1 out of 7 rabbits. Lymphocyte reactivity was present in all 8 dogs. Death occurred in the 2 dogs immunized with the low dose (0.1 mg/kg) of TMA, in 2 of the 4 dogs immunized with the moderate dose (1.0 mg/kg), and in neither of the 2 dogs immunized repeatedly with the high dose (10.0 mg/kg). No correlation of deaths could be made with serum levels of anti-TM-E antibody or anti-TM125I-DSA antibody binding, or lymphocyte reactivity. The deaths occurred early in the TMA immunizations. All antibody levels in the diseased animals were less than those seen in human workers with TMA-related respiratory disease. Autopsy findings in the 4 dogs showed hemorrhagic pneumonitis possibly analogous to the pulmonary lesions seen in the hemorrhagic pneumonitis of some workers exposed to TMA fumes. TMA as used in these experiments was not toxic to dogs as the high doses of TMA (10.0 mg/kg) did not lead to death which did occur at the lower doses. No deaths occurred in the 7 rabbits immunized with 1.0 mg TMA/kg. The immune responses and pathological findings in dogs encourage further work in the development of animal models of TMA immunologic lung disease.

Hybridomas producing hemolytic plaques used to study the relationship between monoclonal antibody affinity and the efficiency of plaque inhibition with increasing concentrations of antigen

Hybridoma clones producing anti-hapten antibodies were established by fusing spleen cells from mice immunized with 4-azophthalate keyhole limpet hemocyanin to drug-resistant non-producing myelomas. The affinity and homogeneity of the immunochemically purified anti-phthalate antibodies were determined by equilibrium dialysis. We report here a broad distribution of the monoclonal antibody affinities ranging from a low of 4.0 X 10(4) to a high of 4.0 X 10(7) (L/M). The binding data for eleven anti-phthalate antibodies described a straight line in a Scatchard plot as would be expected for homogeneous antibodies. We determined that all hybridomas, except those secreting very low affinity antibody, produced hemolytic plaques. The hybridomas made it possible to test several assumptions regarding the association of plaque morphology and plaque inhibition with the affinity of the antibody secreted by the plaque-forming cells. Our studies indicate that the affinity of the antibody secreted by the hybridoma clones does not correlate with either the size of the plaque or with the efficiency with which the hybridoma-produced plaques are inhibited by free hapten. By comparing hybridoma-produced plaques to plaques produced by phthalate-immune spleen cells it has been demonstrated that the plaque size within each hybridoma clone was substantially less heterogeneous than that observed for the immune spleen cells. Our results do support the assumption that the range of free hapten concentration over which PFC are inhibited is a reflection of PFC heterogeneity. The analysis of the PFC inhibition of hybridomas produced an interesting and unexpected result which is reported here. It was observed that subinhibitory doses of free hapten caused an enhancement in the number of hybridoma-produced plaques. The relevance of this finding to the recent observation and interpretation of plaque enhancement (i.e., the displacement of anti-idiotype antibodies) observed for immune spleen cells is discussed.

Human antibodies against trimellityl proteins: comparison of specificities of IgG, IgA and IgE classes

The specificities of antibodies of different Ig classes against trimellityl (TM)-human serum albumin were examined by a radioimmunoassay inhibition technique. The antisera were from workers exposed to trimellitic anhydride who had 4 differing respiratory diseases. The studies demonstrated similarities between reactivities of antibodies of different Ig classes in these workers in that inhibition of antibody to TM-HSA required markedly less TM-HSA on a molar basis than TM-ovalbumin (OA) or sodium trimellitate (NaTM), the hapten for the trimellityl group. The results appears best explained by formation of new antigenic determinants on altered HSA molecules with the TM group forming a component of some of the new antigenic determinants. NaTM in high concentration could not completely inhibit the IgG antibodies of 2 sera suggesting either very low affinity for the hapten or that some of the antibodies might possibly be directed against new antigenic determinants formed from the reaction of TMA with HSA but that the TM group might not be a part of the antigenic specificity. The results of some studies also suggested that there were similar antigenic specificities on TM-HSA and TM-OA but of lesser concentration or lower affinity on the latter molecules. Passive transfer studies using a serum containing IgE antibodies against TM-HSA demonstrated that these human IgE antibodies will passively sensitize rhesus monkey skin. Neutralization of the cutaneous IgE antibodies occurred with TM-HSA but not with a great molar excess of NaTM in analogy with the in vitro studies.

Thymolysis induced by EN3638 and other drugs and its relation to immunosuppression

The effect on the thymus of EN3638, an oxime derivative of salicylic acid, was investigated because the drug has immunosuppressive properties. It caused a moderate reduction in thymic weight of normal adult and weanling rats and it retarded the regeneration of the thymus that follows acute corticosteroid-induced involution. These effects of EN3638 were not mediated by the adrenal nor due to the salicylate part of the molecule. At high dose levels, the drug also reduced slightly the weight of spleen and lymph nodes and the rate of body growth. Thymolytic doses of EN3638 were also immunosuppressive for experimental allergic encephalomyelitis (EAE). At doses that caused equivalent degrees of thymolysis. EN3638 was somewhat more potent for suppression of EAE than cyclophophosphamide or hydrocortisone.

Asthma due to inhaled chemical agents--epoxy resin systems containing phthalic acid anhydride, trimellitic acid anhydride and triethylene tetramine

Six workers with a diagnosis of occupational asthma and one with chronic bronchitis were examined for sensitivity to epoxy resin systems and certain of their components. In six cases the chemical agent responsible for their symptoms was identified by careful inhalation challenge testing, simulating their exposure at work and thus providing a precise aetiological diagnosis. In one worker asthma followed exposure to triethylene tetramine fume; four were sensitive to acid anhydrides, three to phthalic acid anhydride as a fume or powder and one to trimellitic anhydride. On worker thought to be sensitive to toluene di-isocyanate gave negative reactions to this and positive reactions to a phthalic acid anhydride epoxy resin and another thought to have asthma from acid anhydride fumes was found to be sensitive only to toluene di-isocyanate. Immediate, non-immediate or combined asthmatic reactions were elicited.

Phthalic anhydride asthma

A patient with occupational asthma caused by phthalic anhydride is described. Inhalation challenges under laboratory control produced immediate and delayed asthmatic responses. Repeat exposure to phthalic anhydride after treatment with cromolyn sodium showed inhibition of the late but not early bronchoconstrictive, asthmatic response.