Toll-like receptor 3 L412F polymorphism promotes a persistent clinical phenotype in pulmonary sarcoidosis

BACKGROUND/INTRODUCTION

Sarcoidosis is a multi-systemic disorder of unknown etiology, characterized by the presence of non-caseating granulomas in target organs. In 90% of cases, there is thoracic involvement. Fifty to seventy percent of pulmonary sarcoidosis patients will experience acute, self-limiting disease. For the subgroup of patients who develop persistent disease, no targeted therapy is currently available.

AIM

To investigate the potential of the single nucleotide polymorphism (SNP), Toll-like receptor 3 Leu412Phe (TLR3 L412F; rs3775291), as a causative factor in the development of and in disease persistence in pulmonary sarcoidosis. To investigate the functionality of TLR3 L412F in vitro in primary human lung fibroblasts from pulmonary sarcoidosis patients.

DESIGN

SNP-genotyping and cellular assays, respectively, were used to investigate the role of TLR3 L412F in the development of persistent pulmonary sarcoidosis.

METHODS

Cohorts of Irish sarcoidosis patients (n = 228), healthy Irish controls (n = 263) and a secondary cohort of American sarcoidosis patients (n = 123) were genotyped for TLR3 L412F. Additionally, the effect of TLR3 L412F in primary lung fibroblasts from pulmonary sarcoidosis patients was quantitated following TLR3 activation in the context of cytokine and type I interferon production, TLR3 expression and apoptotic- and fibroproliferative-responses.

RESULTS

We report a significant association between TLR3 L412F and persistent clinical disease in two cohorts of Irish and American Caucasians with pulmonary sarcoidosis. Furthermore, activation of TLR3 in primary lung fibroblasts from 412 F-homozygous pulmonary sarcoidosis patients resulted in reduced IFN-β and TLR3 expression, reduced apoptosis- and dysregulated fibroproliferative-responses compared with TLR3 wild-type patients.

DISCUSSION/CONCLUSION

This study identifies defective TLR3 function as a previously unidentified factor in persistent clinical disease in pulmonary sarcoidosis and reveals TLR3 L412F as a candidate biomarker.

Genome-wide search for sarcoidosis susceptibility genes in African Americans

Sarcoidosis, a systemic granulomatous disease of unknown etiology, likely results from an environmental insult in a genetically susceptible host. In the US, African Americans are more commonly affected with sarcoidosis and suffer greater morbidity than Caucasians. We searched for sarcoidosis susceptibility loci by conducting a genome-wide, sib pair multipoint linkage analysis in 229 African-American families ascertained through two or more sibs with a history of sarcoidosis. Using the Haseman-Elston regression technique, linkage peaks with P-values less than 0.05 were identified on chromosomes 1p22, 2p25, 5p15-13, 5q11, 5q35, 9q34, 11p15 and 20q13 with the most prominent peak at D5S2500 on chromosome 5q11 (P=0.0005). We found agreement for linkage with the previously reported genome scan of a German population at chromosomes 1p and 9q. Based on the multiple suggestive regions for linkage found in our study population, it is likely that more than one gene influences sarcoidosis susceptibility in African Americans. Fine mapping of the linked regions, particularly on chromosome 5q, should help to refine linkage signals and guide further sarcoidosis candidate gene investigation.

Treatment of sarcoidosis -- from a basic science point of view

Progress in our understanding of the scientific basis of granulomatous inflammation in sarcoidosis provides a framework for enlightened treatment decisions. Current evidence supports the concept that the pathogenesis of sarcoidosis involves a highly polarized T-helper 1 (Th1) immune response to pathogenic tissue antigens. Conventional treatment is focused on attenuating granuloma formation with antimalarial drugs that inhibit antigen presentation or with nonspecific anti-inflammatory agents such as glucocorticosteroids, methotrexate, or azathioprine. Anti-tumour necrosis factor (TNF)-alpha agents such as pentoxifylline, thalidomide, etanercept and remicade, have recently shown some successes in sarcoidosis. Designing future therapies depends on improved knowledge of the critical immunological processes operative in different stages of disease.

Familial aggregation of sarcoidosis. A case-control etiologic study of sarcoidosis (ACCESS)

Despite reports of familial clustering of sarcoidosis, little empirical evidence exists that disease risk in family members of sarcoidosis cases is greater than that in the general population. To address this question, we estimated sarcoidosis familial relative risk using data on disease occurrence in 10,862 first- and 17,047 second-degree relatives of 706 age, sex, race, and geographically matched cases and controls who participated in the multicenter ACCESS (A Case-Control Etiology Study of Sarcoidosis) study from 1996 to 1999. Familial relative risk estimates were calculated using a logistic regression technique that accounted for the dependence between relatives. Sibs had the highest relative risk (odds ratio [OR] = 5.8; 95% confidence interval [CI] = 2.1-15.9), followed by avuncular relationships (OR = 5.7; 95% CI = 1.6-20.7), grandparents (OR = 5.2; 95% CI = 1.5-18.0), and then parents (OR = 3.8; 95% CI = 1.2-11.3). In a multivariate model fit to the parents and sibs data, the familial relative risk adjusted for age, sex, relative class, and shared environment was 4.7 (95% CI = 2.3-9.7). White cases had a markedly higher familial relative risk compared with African-American cases (18.0 versus 2.8; p = 0.098). In summary, a significant elevated risk of sarcoidosis was observed among first- and second-degree relatives of sarcoidosis cases compared with relatives of matched control subjects.

Clinical characteristics of patients in a case control study of sarcoidosis

Sarcoidosis may be affected by sex, race, and age. A Case Control Etiologic Study of Sarcoidosis (ACCESS) enrolled 736 patients with sarcoidosis within 6 mo of diagnosis from 10 clinical centers in the United States. Using the ACCESS sarcoidosis assessment system, we determined organ involvement for the whole group and for subgroups differentiated by sex, race, and age (less than 40 yr or 40 yr and older). The study population was heterogeneous in terms of race (53% white, 44% black), sex (64% female, 36% male), and age (46% < 40 yr old, 54% > or = 40 yr old). Women were more likely to have eye and neurologic involvement (chi(2) = 4.74, p < 0.05 and chi(2) = 4.60, p < 0.05 respectively), have erythema nodosum (chi(2) = 7.28, p < 0.01), and to be age 40 yr or over (chi(2) = 6.07, p < 0.02) whereas men were more likely to be hypercalcemic (chi(2) = 7.38, p < 0.01). Black subjects were more likely to have skin involvement other than erythema nodosum (chi(2) = 5.47, p < 0.05), and eye (chi(2) = 13.8, p < 0.0001), liver (chi(2) = 23.3, p < 0.0001), bone marrow (chi(2) = 18.8, p < 0.001), and extrathoracic lymph node involvement (chi(2) = 7.21, p < 0.01). We conclude that the initial presentation of sarcoidosis is related to sex, race, and age.

Attenuation of Lung Inflammation and Fibrosis in Interferon- γ –Deficient Mice after Intratracheal Bleomycin

Because mouse strains susceptible to bleomycin, such as C57BL/ 6J, tend to produce T helper type 1 (Th1) cytokines in response to immune activation, we hypothesized that the inflammatory response to bleomycin is mediated, in part, by local production of the Th1 cytokine interferon-gamma (IFN-gamma). Consistent with this hypothesis, fibrosis-prone C57BL/6J and A/J mice demonstrated significantly elevated expression of IFN-gamma protein (by enzyme-linked immunosorbent assay) in bronchoalveolar lavage fluid at 24 h, and subsequently increased lung inflammation, weight loss, and mortality 10 d after intratracheal bleomycin administration compared with fibrosis-resistant BALB/c mice or saline control mice. To directly determine a role for IFN-gamma in bleomycin toxicity, we exposed C57BL/6J mice with a homozygous null mutation of the IFN-gamma gene (IFN-gamma[-/-]) and wild-type C57BL/6J mice to intratracheal bleomycin. IFN-gamma(-/-) mice demonstrated significantly lower parenchymal inflammation, weight loss, and mortality 10 d after 5 U/kg intratracheal bleomycin administration compared with control mice. At 3 wk after 1.5 U/kg bleomycin exposure, single lung collagen determined by hydroxyproline assay was significantly lower in IFN-gamma(-/-) mice compared with wild-type C57BL/6J mice. Together, these results suggest that IFN-gamma mediates, in part, bleomycin-induced pulmonary inflammation and fibrosis.

Depression in sarcoidosis

Sarcoidosis, a chronic, multisystem disease, impacts quality of life and may increase depression risk. No previous study has reported the depression prevalence among U.S. sarcoid patients. This cross-sectional study examined sociodemographic and disease morbidity factors associated with depression. Patients diagnosed for > or = 1 yr and treated at one of six centers were eligible (n = 176); 154 completed a questionnaire of demographics, treatment, access to medical care, and a short-form Center for Epidemiologic Studies- Depression Scale (CES-D). The primary outcome variable was a CES-D score of > or = 9, indicating clinical depression. The prevalence of depression was 60%. Gender, income, access to medical care, dyspnea on exertion, and number of systems involved were associated with depression. Female sex, decreased access to medical care, and increased dyspnea predicted depression (odds ratio [OR] = 3.33, 11.64, and 2.78, respectively) after adjusting for race, income, and steroid therapy. Despite tertiary care access, patients reported medical care limitation. Health care providers must be sensitive to multiple barriers faced by chronic sarcoid patients; acknowledging depression risk and improving access to medical care will promote better overall health among sarcoid patients. Future studies of sarcoidosis will need to address depression diagnosis and treatment.

Cells and cytokines involved in the pathogenesis of sarcoidosis

Granulomatous inflammation develops under the regulatory influence of cytokines produced by local mononuclear phagocytes, T cells, dendritic cells, fibroblasts, and other local cells. In sarcoidosis, granulomatous inflammation is characterized by dominant expression of T helper 1 (Th1) cytokines such as IFN gamma and interleukin (IL)-2 with low levels of expression of T helper 2 (Th2) cytokines such as IL4 and IL5. Recent studies show that the cytokine IL12, the most important regulator of Th1 immune responses currently known, is upregulated at sites of inflammation in sarcoidosis. In particular, enhanced expression of IL12 is seen in sarcoid lung and lymph node, along with dysregulated production of IL12 by stimulated and unstimulated sarcoid alveolar macrophages. The known dependence of granulomatous inflammation on type 1 cytokines (IFN gamma, IL12) in many experimental models of granulomatous disease makes it likely that these cytokines function in a similar fashion in the initiation and maintenance of granulomatous inflammation in sarcoidosis. Whether these same type 1 cytokines drive granulomatous inflammation in patients with extensive fibrocystic lung disease remains unknown. TGF beta, a known inhibitor of IL12 and IFN gamma production, is produced at higher levels by lung cells from those patients who undergo remission of their disease, suggesting that TGF gamma is important in downregulating granulomatous inflammation in sarcoidosis. These studies offer new insight into the molecular mechanisms of granuloma formation in sarcoidosis and provide a framework for developing new therapeutic strategies for the treatment of this disease.

Involvement of T cells and alterations in T cell receptors in sarcoidosis

Sarcoidosis is recognized to be a multisystem granulomatous disease characterized by activated, cytokine-producing T cells and macrophages at sites of inflammation. The purpose of this article is to review new evidence concerning the role of T cells in sarcoidosis. Recent work on the molecular structure and repertoire of T cell receptor genes in sarcoidosis provide direct evidence that sarcoidosis is characterized by selective expansions of oligoclonal populations of T cells at sites of inflammation, consistent with local antigen-driven immune responses. In addition, data on cytokine production in sarcoidosis indicate that tissue inflammation is dominated by expression of type 1 (T helper 1) cytokines such as interferon-gamma and interleukin-12 that, in keeping with experimental models of granulomatous diseases, likely orchestrate the granulomatous response. These studies offer new insight into the molecular mechanisms of granuloma formation in sarcoidosis and provide a framework for developing new therapeutic strategies for the treatment of this disease.

T-cell receptor genes in sarcoidosis

The pathogenesis of sarcoidosis involves activated, cytokine-producing T-cells and macrophages that regulate granulomatous inflammation. At sites of inflammation, T-cells demonstrate reduced surface density of the CD3 component of the T-cell receptor complex, a hallmark of T-cells activated through the T-cell antigen receptor pathway. The stimulus activating these T-cells is unknown. Conventional antigens selectively stimulate T-cells expressing T-cell receptors with specific variable (V) and hypervariable VDJ or VJ region amino acid sequences while superantigens stimulate larger subsets of T-cells based primarily on their expression of specific V beta genes. Recent studies show that subgroups of patients with sarcoidosis are characterized by biased expression of specific V beta, V alpha, or gamma delta + T-cell receptor genes in T-cell subsets from lung, blood and at sites of Kveim-Siltzbach skin reactions. In addition, investigations on the molecular structure of T-cell receptor genes in sarcoidosis provide direct evidence that biased expression of specific alpha beta + or gamma delta + T-cells at sites of inflammation involves selective expansion of oligoclonal populations of T-cells, consistent with an immune response to a conventional antigen (s). Together, these studies provide direct evidence that sarcoidosis is an antigen-driven disorder at sites of granulomatous inflammation. The identification of key, clonally-expanded T-cell populations in sarcoidosis provides a potential tool for determining the specific antigens involved in the pathogenesis of sarcoidosis.

Etiology of sarcoidosis

Since sarcoidosis was first recognized as a distinct clinical entity, investigators have speculated that a transmissible agent may cause sarcoidosis. Recent attempts at directly isolating infectious organisms or indirectly detecting microbial DNA or RNA from sarcoid tissue have led to inconclusive results. Studies on the immunopathogenic origins of sarcoidosis have provided evidence of persistent antigenic stimulation at sites of inflammation that are associated with dysregulated cytokine production. To date, however, the challenge of defining the cause of sarcoidosis remains unmet.

Inhibition of IL-12 production by thalidomide

The immunomodulatory properties of thalidomide are currently being exploited therapeutically in conditions as diverse as erythema nodosum leprosum, chronic graft-vs-host disease, rheumatoid arthritis, and sarcoidosis. The relevant mechanism of action of thalidomide in these diseases remains unclear. The important role recently ascribed to IL-12, a cytokine critical to the development of cellular immune responses, in the pathogenesis of several of these conditions led us to examine whether thalidomide affects the production of IL-12. Thalidomide potently suppressed the production of IL-12 from human PBMC and primary human monocytes in a concentration-dependent manner. Thalidomide-induced inhibition of IL-12 production was additive to that induced by suboptimal inhibiting doses of dexamethasone, and occurred by a mechanism independent of known endogenous inhibitors of IL-12 production. These results suggest that thalidomide may have therapeutic utility in a wide range of immunologic disorders that are characterized by inappropriate cellular immune responses.

Inhibition of IL-12 production by thalidomide

The immunomodulatory properties of thalidomide are currently being exploited therapeutically in conditions as diverse as erythema nodosum leprosum, chronic graft-vs-host disease, rheumatoid arthritis, and sarcoidosis. The relevant mechanism of action of thalidomide in these diseases remains unclear. The important role recently ascribed to IL-12, a cytokine critical to the development of cellular immune responses, in the pathogenesis of several of these conditions led us to examine whether thalidomide affects the production of IL-12. Thalidomide potently suppressed the production of IL-12 from human PBMC and primary human monocytes in a concentration-dependent manner. Thalidomide-induced inhibition of IL-12 production was additive to that induced by suboptimal inhibiting doses of dexamethasone, and occurred by a mechanism independent of known endogenous inhibitors of IL-12 production. These results suggest that thalidomide may have therapeutic utility in a wide range of immunologic disorders that are characterized by inappropriate cellular immune responses.

Inhibition of human interleukin-12 production by pentoxifylline

Pharmacological control of interleukin-12 (IL-12) production may be a key therapeutic strategy for modulating immunological diseases dominated by type-1 cytokine responses. In this study, we investigated the effects of pentoxifylline on the production of IL-12 by human blood mononuclear cells and primary human monocytes stimulated with heat-killed Staphylococcus aureus Cowan strain I (SAC) or lipopolysaccharide (LPS). Pentoxifylline potently suppressed production of IL-12 in a concentration-dependent manner. In these same experiments, tumour necrosis factor-alpha (TNF-alpha) production was inhibited and IL-10 and prostaglandin E2 (PGE2) production was enhanced by treatment with pentoxifylline. Suppression of IL-12 production by pentoxifylline was found to be independent of several known endogenous inhibitors of IL-12, such as IL-10, transforming growth factor-beta (TGF-beta), IL-4 and PGE2. RNase protection assays revealed that pentoxifylline inhibited accumulation of both IL-12 p40 and p35 mRNA, suggesting a predominant mRNA locus for pentoxifylline-induced IL-12 inhibition. Low levels of pentoxifylline added to the suppression of IL-12 production by suboptimal inhibiting doses of dexamethasone, suggesting that this drug combination may have therapeutic utility. These results provide a firm rationale for the use of pentoxifylline in clinical trials of immunological disorders characterized by inappropriate type-1 immune responses.

Limited heterogeneity of biased T-cell receptor V beta gene usage in lung but not blood T cells in active pulmonary sarcoidosis

Sarcoidosis is a multisystem disorder characterized by non-caseating granulomas and the accumulation of CD4+ T cells in involved tissues such as the lung. To evaluate the diversity of the CD4+ T-cell repertoire in this disorder, a detailed clonal analysis was performed in five individuals with active sarcoidosis who demonstrated preferential accumulation of T cells expressing the T-cell receptor variable gene family V beta 8 in either the lung or blood. In three individuals, analysis of unselected samples of nucleotide sequences derived from V beta 8+ lung T cells demonstrated degrees of clonality ranging from 11% to 46%, indicating the expansion of limited numbers of V beta 8+ T-cell clones in the lung. Analysis of the corresponding deduced amino acid sequences demonstrated common VDJ junctional amino acid residues in the dominant V beta 8+ T-cell clones derived from two oligoclonal V beta 8+ lung T-cell populations, consistent with an antigen-specific T-cell response. In contrast, analysis of V beta 8+ CD4+ T cells from the blood of an individual with a marked bias for peripheral blood V beta 8+ T cells demonstrated no evidence of oligoclonality, suggesting that the stimulus for circulating biased V beta-specific T cells in sarcoidosis may derive from a different, perhaps superantigenic, origin. Clinical improvement in the disease either in response to treatment with corticosteroids or as a result of spontaneous resolution was associated with a decrease in the proportion of V beta 8-specific T cells in the biased lung and/or blood T-cell compartments. Together, these observations are consistent with a role for this T-cell subset in the clinical manifestations of active granulomatous disease.

Enhanced expression of IL-12 associated with Th1 cytokine profiles in active pulmonary sarcoidosis

Sarcoidosis is a multisystem granulomatous disease of unknown etiology characterized by the expansion of activated oligoclonal CD4+ T cells and macrophages at sites of disease. To investigate the immunopathogenesis of sarcoidosis, we analyzed patterns of cytokine expression in bronchoalveolar lavage cells and fluid from patients with pulmonary sarcoidosis and idiopathic pulmonary fibrosis and from normal volunteers. We found dominant type 1 cytokine expression, with elevated mRNA and protein levels of IFN-gamma, but not IL-4, in sarcoid lung cells and fluid compared with those in normal samples. To define immunoregulatory mechanisms important to this type 1 response, we analyzed the expression of IL-12 and IL-10 in lung cells and fluid. Using semiquantitative PCR, we found significantly higher mRNA expression of the regulated IL-12 p40 subunit, but not IL-10, in sarcoid compared with normal lung cells. Consistent with these observations, strikingly elevated levels of p40 protein were found in sarcoid compared with normal bronchoalveolar lavage fluid. Unstimulated and Staphylococcus aureus-stimulated sarcoid alveolar macrophages produced greater amounts of IL-12 than normal alveolar macrophages when cultured in vitro. We hypothesize that sarcoidosis is a Th1-mediated disease driven by chronic, dysregulated production of IL-12 at sites of disease.

Enhanced expression of IL-12 associated with Th1 cytokine profiles in active pulmonary sarcoidosis

Sarcoidosis is a multisystem granulomatous disease of unknown etiology characterized by the expansion of activated oligoclonal CD4+ T cells and macrophages at sites of disease. To investigate the immunopathogenesis of sarcoidosis, we analyzed patterns of cytokine expression in bronchoalveolar lavage cells and fluid from patients with pulmonary sarcoidosis and idiopathic pulmonary fibrosis and from normal volunteers. We found dominant type 1 cytokine expression, with elevated mRNA and protein levels of IFN-gamma, but not IL-4, in sarcoid lung cells and fluid compared with those in normal samples. To define immunoregulatory mechanisms important to this type 1 response, we analyzed the expression of IL-12 and IL-10 in lung cells and fluid. Using semiquantitative PCR, we found significantly higher mRNA expression of the regulated IL-12 p40 subunit, but not IL-10, in sarcoid compared with normal lung cells. Consistent with these observations, strikingly elevated levels of p40 protein were found in sarcoid compared with normal bronchoalveolar lavage fluid. Unstimulated and Staphylococcus aureus-stimulated sarcoid alveolar macrophages produced greater amounts of IL-12 than normal alveolar macrophages when cultured in vitro. We hypothesize that sarcoidosis is a Th1-mediated disease driven by chronic, dysregulated production of IL-12 at sites of disease.

Selection of oligoclonal V beta-specific T cells in the intradermal response to Kveim-Siltzbach reagent in individuals with sarcoidosis

Sarcoidosis is a multiorgan granulomatous disorder of unknown etiology characterized by noncaseating granulomas in involved tissues. A positive Kveim-Siltzbach reaction is a granulomatous response to an intradermal injection of a suspension of sarcoid tissue extract in individuals with sarcoidosis. The protracted time course and granulomatous features of this reaction have a striking resemblance to the Mitsuda reaction in tuberculous leprosy, which suggests that the Kveim-Siltzbach reaction is a response to an unknown Ag(s). To evaluate whether this reaction is Ag-driven, an analysis of the TCR V beta repertoire in 15 Kveim-Siltzbach reaction sites was performed using a PCR technique and primers specific for 20 V beta gene families. Results of this analysis demonstrated a pattern of V beta expression dominated by expression of V beta 2, V beta 3, V beta 6, or V beta 8 to levels &gt; 20% of total V beta gene expression in nine of 15 individuals. Analysis of paired biopsy and blood specimens revealed a preferential expression of specific V beta genes, such as V beta 3, V beta 5, and V beta 8, at sites of Kveim-Siltzbach reactions to levels four to seven times that of the corresponding peripheral blood. Sequence analysis demonstrated that preferential expression of specific V beta genes at Kveim-Siltzbach reaction sites is oligoclonal. Furthermore, the dominant V beta 8 sequence present at one of the reaction sites contained a sequence motif in the variable-diversity-joining junctional region previously identified in sarcoid lung and blood T cell populations. These results suggest that the Kveim-Siltzbach reaction is characterized by a limited TCR beta-chain repertoire consistent with an Ag-driven T cell immune response.

Selection of oligoclonal V beta-specific T cells in the intradermal response to Kveim-Siltzbach reagent in individuals with sarcoidosis

Sarcoidosis is a multiorgan granulomatous disorder of unknown etiology characterized by noncaseating granulomas in involved tissues. A positive Kveim-Siltzbach reaction is a granulomatous response to an intradermal injection of a suspension of sarcoid tissue extract in individuals with sarcoidosis. The protracted time course and granulomatous features of this reaction have a striking resemblance to the Mitsuda reaction in tuberculous leprosy, which suggests that the Kveim-Siltzbach reaction is a response to an unknown Ag(s). To evaluate whether this reaction is Ag-driven, an analysis of the TCR V beta repertoire in 15 Kveim-Siltzbach reaction sites was performed using a PCR technique and primers specific for 20 V beta gene families. Results of this analysis demonstrated a pattern of V beta expression dominated by expression of V beta 2, V beta 3, V beta 6, or V beta 8 to levels > 20% of total V beta gene expression in nine of 15 individuals. Analysis of paired biopsy and blood specimens revealed a preferential expression of specific V beta genes, such as V beta 3, V beta 5, and V beta 8, at sites of Kveim-Siltzbach reactions to levels four to seven times that of the corresponding peripheral blood. Sequence analysis demonstrated that preferential expression of specific V beta genes at Kveim-Siltzbach reaction sites is oligoclonal. Furthermore, the dominant V beta 8 sequence present at one of the reaction sites contained a sequence motif in the variable-diversity-joining junctional region previously identified in sarcoid lung and blood T cell populations. These results suggest that the Kveim-Siltzbach reaction is characterized by a limited TCR beta-chain repertoire consistent with an Ag-driven T cell immune response.

Selective activation and accumulation of oligoclonal V beta-specific T cells in active pulmonary sarcoidosis

Sarcoidosis is a granulomatous disease in which activated T cells, responding to an unidentified stimulus, accumulate at sites of disease such as the lung. To evaluate the hypothesis that active sarcoidosis is characterized by a selective activation and expansion of a limited repertoire of T cell receptor (TCR) specific T cells, we analyzed TCR V beta gene expression in lung and blood T cells of patients with active sarcoidosis and, for comparison, normal individuals using polymerase chain reaction amplification of 20 V beta gene families. Analysis of normal bronchoalveolar lavage T cells revealed TCR V beta distributions similar to that of normal blood, providing evidence for a lack of generalized skewing of the T cell repertoire in the normal, noninfected lung. Compared to normal lung and blood, subgroups of individuals with sarcoidosis demonstrated biased expression of one or more V beta genes in either the lung or blood. Five V beta gene families (V beta 5, V beta 8, V beta 15, V beta 16, and V beta 18) were most frequently utilized in a biased fashion by sarcoid lung or blood T cells. Furthermore, dramatic skewing of the T cell repertoire was apparent when sarcoid lung and blood T cells were expanded by short-term culture with IL-2. Sequence analysis demonstrated a bias in V beta gene expression was usually due to expansion of select V beta-specific clones, some of which contained a similar V(D)J junctional region motif. These observations provide evidence for a selective activation and accumulation of antigen-specific V beta-expressing T cells in sarcoidosis.

Preferential usage of the T-cell antigen receptor beta-chain constant region C beta 1 element by lung T-lymphocytes of patients with pulmonary sarcoidosis

Evaluation of the T-cells accumulating at sites of disease in active sarcoidosis suggests the accumulation process is not random, evidenced by a bias in the types of T-cells present. To evaluate the concept that this bias extends to the accumulation of T-cells with the preferential use of specific T-cell antigen receptor (TCR) beta-chain constant region elements, beta-chain mRNA transcripts of lung and blood T-cells of normal subjects and patients with pulmonary sarcoidosis were compared for the relative usage of constant region beta 1 or beta 2 elements. Quantitative evaluation of C beta 1 and C beta 2 mRNA transcripts demonstrated a C beta 1/C beta 2 usage in normal blood of 0.63 +/- 0.02, similar to that of normal lung (0.64 +/- 0.06, p greater than 0.7), and in sarcoid blood (0.59 +/- 0.03, p greater than 0.2). In contrast, the lung T-lymphocytes of patients with sarcoidosis reflected a marked bias in the usage of C beta 1 elements (C beta 1/C beta 2: 0.88 +/- 0.06, p less than 0.001 compared with sarcoid blood and normal blood; p less than 0.02 compared with normal lung). Interestingly, a subgroup of these patients (six of 18) showed a markedly exaggerated skewing in the use of C beta 1 elements (C beta 1/C beta 2 ratio greater than 1, i.e., greater than 3 standard deviations above mean), demonstrating heterogeneity among sarcoid patients with regard to specific C beta 1 usage.(ABSTRACT TRUNCATED AT 250 WORDS)

Increased numbers of T lymphocytes with gamma delta-positive antigen receptors in a subgroup of individuals with pulmonary sarcoidosis

Individuals with sarcoidosis were evaluated for preferential usage of T cells with the gamma delta-positive (+) type of T cell antigen receptor. Compared with normal subjects (n = 19), the group with sarcoidosis had increased numbers of CD3+ alpha beta-negative (-) T cells in the blood (normal, 58 +/- 12 cells/microliters; sarcoid, 192 +/- 45 cells/microliters, P less than 0.05) and in the epithelial lining fluid of the lung (normal, 78 14 cells/microliters; sarcoid, 240 +/- 60 cells/microliters, P less than 0.04) and a concomitant elevated number of blood and lung CD3+ gamma delta+ T cells, owing to a striking increase in the number of CD3+ gamma delta+ T cells in a subgroup (7 of 20) of sarcoid individuals. The elevated numbers of sarcoid blood gamma delta+ T lymphocytes were mostly Ti gamma A+ and delta TCS1-, a pattern also seen in normal individuals, consistent with the majority of gamma delta+ T cells expressing one gamma-chain variable region, V gamma 9. The observation of an increase in the total gamma delta+ T cell numbers in a sarcoid subgroup suggests that various specific stimuli may trigger the expansion of different T cell subpopulations within different groups of individuals with sarcoidosis.

Bias toward use of a specific T cell receptor beta-chain variable region in a subgroup of individuals with sarcoidosis

To evaluate the concept that biases in the usage of T cell antigen receptor beta variable (V) regions may be manifested in T lymphocytes that accumulate in nonmalignant, T cell-mediated human disorders, a V beta 8-specific antibody (anti-Ti3A, 5REX9H5) was used to evaluate lung and blood T cells in pulmonary sarcoidosis, a chronic granulomatous disorder of unknown etiology. Whereas normal patients had less than 5% Ti3A+ lung (n = 7) and/or blood (n = 9) lymphocytes, strikingly, a subgroup (8 of 21) with active pulmonary sarcoidosis had greater than 7% Ti3A+ lung and/or blood T cells and a higher proportion of Ti3A+ lymphocytes in the lung compared with blood. Dual-color flow cytometry demonstrated compartmentalization of Ti3A+ CD4+ lymphocytes to lung and Ti3A+ CD8+ lymphocytes to blood. Analysis with a 32P-labeled V beta 8 probe revealed that sarcoid lung T lymphocytes contained higher amounts of V beta 8+ mRNA than autologous blood T cells. However, Southern analysis of sarcoid lung and blood T cell DNA demonstrated no evidence of clonal rearrangements of V beta 8 genes. These observations demonstrate a clear bias toward the use of at least one V beta region in sarcoidosis, and suggests T cells accumulate secondary to external selective pressure, rather than in a random polyclonal fashion or by clonal expansion of one or few T cell clones.

Spontaneous expression of the interleukin 2 receptor gene and presence of functional interleukin 2 receptors on T lymphocytes in the blood of individuals with active pulmonary sarcoidosis

Current concepts of the pathogenesis of sarcoidosis suggest that the expanded numbers of activated T-helper/inducer cells at sites of disease activity result, at least in part, from their proliferation in the local milieu. Normal clonal proliferation of T cells involves activation and expression of the IL 2 receptor (IL 2R) gene. Thus, knowing that IL 2R mRNA transcripts are relatively long lived, we hypothesized that sarcoid blood T cells may contain IL 2R mRNA transcripts and express functional surface IL 2R, although the cells are probably activated elsewhere. Northern analysis using a 32P-labeled cDNA probe for the IL 2R p55 protein demonstrated that blood T cells of patients with active sarcoidosis, but not of normal patients, express 3.5- and 1.5-kb IL 2R mRNA transcripts, the same as those observed in normal T cells activated in vitro. Consistent with this, using flow cytometry and an MAb directed against the IL 2R p55 protein (2A3), we observed detectable levels of IL 2R surface protein on increased numbers of blood T cells of active sarcoidosis patients (4.7 +/- 0.9%) compared with blood T cells of normal patients (0.9 +/- 0.2%). Importantly, when the sarcoid blood T cells were exposed to IL 2 in vitro, they proliferated at a rate greater than that of normal blood T cells under the same conditions, suggesting that the IL 2R spontaneously expressed by sarcoid blood T cells were functionally active. In the context of the known compartmentalization of spontaneous IL 2 production and T cell proliferation at sites of disease in active pulmonary sarcoidosis, these IL 2R positive blood T cells would probably have a proliferative advantage if they trafficked to sites of active sarcoidosis, such as the lower respiratory tract.

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.

Clinical and immunologic studies among egg-processing workers with occupational asthma

Twenty-five workers in an egg-processing factory were evaluated for respiratory sensitization to inhaled egg proteins by a physician evaluation, serial peak expiratory flow rate (PEFR) measurements for a 1-week period, and immunologic tests. Immunologic studies included skin prick tests, serum-specific IgE (RAST), and specific IgG (ELISA) to solutions prepared from commercial food allergens: factory-powdered egg white and yolk products and purified egg white fractions, including ovalbumin, ovomucoid, lysozyme, and conalbumin. Six workers had significant daily PEFR lability (greater than 20%) of whom five had associated cutaneous reactivity to at least one egg allergen. A diagnosis of "definite asthma" was established in five workers suspected by the physician of having asthma. These five workers exhibited significant decrements in daily PEFR that were accompanied by bronchial symptoms. Occupational asthma was diagnosed by the physician in four of the five latter workers. Definite asthma was significantly associated with both cutaneous reactivity to egg allergens (p less than 0.01) and RAST binding (p less than 0.01). Of eight workers with cutaneous reactivity to at least one egg reagent, four workers (50%) were positive to only purified egg white fractions. The highest levels of RAST binding were detected in four workers, and the best binding activity was to ovomucoid and ovalbumin fractions. Elevated specific IgG responses were significantly higher in egg-factory workers to whole egg (p less than 0.005), lysozyme (p less than 0.002), and conalbumin (p less than 0.002) allergens compared to responses of nonexposed control subjects. However, no differences in specific IgG were detected between symptomatic and asymptomatic workers.(ABSTRACT TRUNCATED AT 250 WORDS)

Chronic asthma due to toluene diisocyanate

Twelve subjects were studied with inhalation challenge testing to toluene diisocyanate (TDI) because of suspected TDI asthma based on a consistent clinical and occupational history. In seven cases, TDI asthma was documented by a positive inhalation challenge to low levels of TDI. Six of the seven TDI reactors had persistent respiratory symptoms and required daily treatment even though they had been removed from isocyanate exposure for intervals as long as 12 years (mean 4.5 years). These six TDI reactors had either dual (four cases) or late bronchospasm (two cases) to less than 20 ppb TDI, and all had a positive methacholine or cold air challenge prior to study. The one TDI reactor with a negative methacholine challenge had a positive (immediate) bronchospastic response to a TDI challenge performed one week after removal from isocyanate exposure. Five workers had a negative TDI challenge, two of whom had persistent respiratory symptoms and positive methacholine challenges at the time of TDI inhalation testing. We conclude that respiratory symptoms may persist following long-term removal from occupational exposure to TDI and are associated with nonspecific bronchial hyperreactivity. The TDI sensitivity may also persist for a long time even in the absence of any additional occupational exposure. Long-term prospective studies of symptomatic isocyanate workers are needed to fully define the extent of this problem.

Persistent airways disease caused by toluene diisocyanate

The natural history of isocyanate-induced asthma is not well documented. We evaluated a patient who developed persistent shortness of breath, wheezing, and cough after a massive exposure to toluene diisocyanate (TDI). Despite no further occupational exposures to isocyanates, he continued to have symptoms of asthma and variable airway obstruction 12 yr later. A methacholine inhalation challenge test was markedly positive, and a bronchial challenge test to TDI produced a dual asthmatic response. This report demonstrates that sensitivity to TDI can persist for many years in the absence of further occupational exposure and suggests that some patients with TDI-induced asthma do not recover from their disease after being removed from isocyanate exposure.

Delayed anaphylactoid reaction in a worker exposed to chromium

A 29-year-old male welder reported systemic reactions after exposure to chromium. Inhalation challenge testing to 29 micrograms/m3 of sodium chromate aerosol resulted in late appearing systemic urticaria, angioedema, and severe bronchospasm that occurred at the same time as a threefold rise in plasma histamine. A direct leukocyte inhibitory factor test to 5.5 X 10(-6)mol/L Na2CrO4 was positive. Although the mechanism of this reaction is unknown, the positive leukocyte inhibitory factor and the general acceptance of hexavalent chromium as a contact skin sensitizer suggest that cell-mediated mechanisms could be involved.

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.

Asthma and rhinitis due to ethylcyanoacrylate instant glue

A 32-year-old man developed asthma due to a cyanoacrylate ester instant glue used in building remote control model airplanes. Typical asthma and rhinitis symptoms developed after 1 year using the adhesive. Delayed onset of symptoms was consistently related to the application of the glue to balsa wood. Bronchial provocation to the glue vapors in a manner simulating his home exposure resulted in a late asthmatic response with rhinorrhea and lacrimation. Increased bronchial hyperreactivity to methacholine occurred after bronchial challenge and persisted for several weeks. Complete resolution of the patient's asthma symptoms occurred with avoidance of the glue. Reversion to a negative methacholine challenge test occurred after 6 months of continued avoidance.