Exploring the causes of COPD misdiagnosis in primary care: A mixed methods study

BACKGROUND

Within primary care there exists a cohort of patients misdiagnosed with Chronic Obstructive Pulmonary Disease (COPD). Misdiagnosis can have a detrimental impact on healthcare finances and patient health and so understanding the factors leading to misdiagnosis is crucial in order to reduce misdiagnosis in the future. The objective of this study is to understand and explore the perceived causes of COPD misdiagnosis in primary care.

METHODS

A sequential mixed methods study, quantifying prevalence and features of patients misdiagnosed with COPD in primary care followed by a qualitative analysis to explore perceived causes of misdiagnosis. Quantitative data was collected for 206 patients identified as misdiagnosed with COPD within the INTEGR COPD study (NCT03482700). Qualitative data collected from 21 healthcare professionals involved in providing COPD care and 8 misdiagnosed patients who were recruited using a maximum variation purposive sampling.

RESULTS

Misinterpretation of spirometry results was the prevailing factor leading to patients initially being misdiagnosed with COPD, affecting 59% of misdiagnosed patients in this cohort. Of the 99 patients who were investigated for their underlying diagnosis; 41% had normal spirometry and 40% had asthma. Further investigation through qualitative methodology uncovered reluctance to challenge historical misdiagnoses and challenges in differential diagnosis as the underlying explanations for COPD misdiagnosis in this cohort.

CONCLUSIONS

Patients historically diagnosed with COPD without spirometric evidence are at risk of remaining labelled and treated for COPD despite non-obstructive respiratory physiology, leading to a persistent cohort of patients misdiagnosed with COPD in primary care. The lack of spirometry services during and after the COVID19 pandemic in primary care risks adding to the cohort of misdiagnosed patients. Support from respiratory specialists can potentially help to reduce the prevalence of COPD misdiagnosis in primary care.

TRIAL REGISTRATION

NCT03482700.

Real-world experience of nintedanib for progressive fibrosing interstitial lung disease in the UK

Background

Nintedanib slows progression of lung function decline in patients with progressive fibrosing (PF) interstitial lung disease (ILD) and was recommended for this indication within the United Kingdom (UK) National Health Service in Scotland in June 2021 and in England, Wales and Northern Ireland in November 2021. To date, there has been no national evaluation of the use of nintedanib for PF-ILD in a real-world setting.

Methods

26 UK centres were invited to take part in a national service evaluation between 17 November 2021 and 30 September 2022. Summary data regarding underlying diagnosis, pulmonary function tests, diagnostic criteria, radiological appearance, concurrent immunosuppressive therapy and drug tolerability were collected via electronic survey.

Results

24 UK prescribing centres responded to the service evaluation invitation. Between 17 November 2021 and 30 September 2022, 1120 patients received a multidisciplinary team recommendation to commence nintedanib for PF-ILD. The most common underlying diagnoses were hypersensitivity pneumonitis (298 out of 1120, 26.6%), connective tissue disease associated ILD (197 out of 1120, 17.6%), rheumatoid arthritis associated ILD (180 out of 1120, 16.0%), idiopathic nonspecific interstitial pneumonia (125 out of 1120, 11.1%) and unclassifiable ILD (100 out of 1120, 8.9%). Of these, 54.4% (609 out of 1120) were receiving concomitant corticosteroids, 355 (31.7%) out of 1120 were receiving concomitant mycophenolate mofetil and 340 (30.3%) out of 1120 were receiving another immunosuppressive/modulatory therapy. Radiological progression of ILD combined with worsening respiratory symptoms was the most common reason for the diagnosis of PF-ILD.

Conclusion

We have demonstrated the use of nintedanib for the treatment of PF-ILD across a broad range of underlying conditions. Nintedanib is frequently co-prescribed alongside immunosuppressive and immunomodulatory therapy. The use of nintedanib for the treatment of PF-ILD has demonstrated acceptable tolerability in a real-world setting.

Airborne occupational exposures associated with pulmonary sarcoidosis: a systematic review and meta-analysis

The aetiology and pathophysiology of sarcoidosis is ill defined-current hypotheses centre on complex genetic-immune-environmental interactions in an individual, triggering a granulomatous process. The aim of this systematic review is to define and describe which airborne occupational exposures (aOE) are associated with and precede a diagnosis of pulmonary sarcoidosis. The methodology adopted for the purpose was systematic review and meta-analyses of ORs for specified aOE associated with pulmonary sarcoidosis (DerSimonian Laird random effects model (pooled log estimate of OR)). Standard search terms and dual review at each stage occurred. A compendium of aOE associated with pulmonary sarcoidosis was assembled, including mineralogical studies of sarcoidosis granulomas. N=81 aOE were associated with pulmonary sarcoidosis across all study designs. Occupational silica, pesticide and mould or mildew exposures were associated with increased odds of pulmonary sarcoidosis. Occupational nickel and aluminium exposure were associated with a non-statistically significant increase in the odds of pulmonary sarcoidosis. Silica exposure associated with pulmonary sarcoidosis was reported most frequently in the compendium (n=33 studies) and was the most common mineral identified in granulomas. It was concluded that aOE to silica, pesticides and mould or mildew are associated with increased odds of pulmonary sarcoidosis. Equipoise remains concerning the association and relationship of metal dusts with pulmonary sarcoidosis.

Job exposure matrices for occupational respiratory disease: a narrative review

BACKGROUND

Job exposure matrices (JEMs) are epidemiological tools used to provide estimations of occupational exposures when it is not feasible to complete detailed individual occupational histories.

AIMS

To identify and summarize the characteristics of published general population JEMs (GPJEM) of inhalable occupational exposures applied in studies of respiratory disease.

METHODS

MEDLINE and EMBASE databases were searched using pre-defined search terms, with screening performed by two independent reviewers to identify studies reporting the use of a GPJEM. JEM creation papers were subsequently identified and reviewed for each individual GPJEM, noting its characteristics in terms of occupational classification system and exposure estimates.

RESULTS

From 728 studies identified in initial searches, 33 GPJEMs of inhalable occupational exposures were identified. Versions of the International Standards Classification of Occupations were the most used occupational classification system. Binary, probability and intensity-based exposure estimates were most frequently reported in GPJEMs.

CONCLUSIONS

Selection of a GPJEM to apply in epidemiological research should be based on the exposure(s) of interest, time period of occupations under review, geographical region for intended use, occupation classification system used and the exposure estimate outcome.

Occupational lung disease: when should I think of it and why is it important?

Exposure to toxic inhalants in the workplace has the potential to cause (in susceptible individuals) almost any major type of lung disease, such as asthma, COPD and interstitial lung diseases. Patients with occupational lung disease will often present to or will be managed by respiratory specialists without training in occupational respiratory medicine, and patients (or their clinicians) may not identify a link between their disease and their current or a past job. Without an awareness of the range of different occupational lung diseases that exist, their similarity to their non-occupational counterparts, and without directed questioning, these conditions may go unidentified. Patients with occupational lung diseases are often in lower paid work and are disproportionally affected by health inequality. Both clinical and socioeconomic outcomes generally improve if cases are identified early. This allows appropriate advice to be given about the risks of ongoing exposure, clinical management, occupational mobility and, in some cases, eligibility for legal compensation. As respiratory professionals, it is important that these cases are not missed, and if needed, are discussed with a physician with specialised expertise. Here we describe some of the most common occupational lung diseases and outline the diagnostic and treatment approach.

Novel occupational causes of hypersensitivity pneumonitis

PURPOSE OF REVIEW

Hypersensitivity pneumonitis (HP) remains a challenging diagnosis, and a cause is not established in up to 50% of cases. This paper aims to update clinicians on traditional and novel occupational causes of HP, and clinical tools for identifying of causative exposures and antigens.

RECENT FINDINGS

Metalworking fluid has become the most frequently cited occupational cause of HP, though geographical variations in exposures exist. Occupational HP is usually associated with work-related symptoms. Systematically derived questionnaires and compendia for HP have been developed for use in cryptogenic disease, though have previously lacked validation; these may help identify inciting antigens or relevant occupational exposures.

SUMMARY

Clinicians should enquire about job roles and work-relatedness of symptoms when considering a diagnosis of HP. Outbreaks of metalworking fluid associated HP from around the world are well described, so clinicians should remain vigilant. The usual classification for causative antigen includes animal and plant proteins, fungi, bacteria, low-molecular weight chemicals and metals; however novel occupational exposures and work processes are frequently reported.

Pulmonary function test and computed tomography features during follow-up after SARS, MERS and COVID-19: a systematic review and meta-analysis

Background

The COVID-19 pandemic follows severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) coronavirus epidemics. Some survivors of COVID-19 infection experience persistent respiratory symptoms, yet their cause and natural history remain unclear. Follow-up after SARS and MERS may provide a model for predicting the long-term pulmonary consequences of COVID-19.

Methods

This systematic review and meta-analysis aims to describe and compare the longitudinal pulmonary function test (PFT) and computed tomography (CT) features of patients recovering from SARS, MERS and COVID-19. Meta-analysis of PFT parameters (DerSimonian and Laird random-effects model) and proportion of CT features (Freeman-Tukey transformation random-effects model) were performed.

Findings

Persistent reduction in the diffusing capacity for carbon monoxide following SARS and COVID-19 infection is seen at 6 months follow-up, and 12 months after MERS. Other PFT parameters recover in this time. 6 months after SARS and COVID-19, ground-glass opacity, linear opacities and reticulation persist in over 30% of patients; honeycombing and traction dilatation are reported less often. Severe/critical COVID-19 infection leads to greater CT and PFT abnormality compared to mild/moderate infection.

Interpretation

Persistent diffusion defects suggestive of parenchymal lung injury occur after SARS, MERS and COVID-19 infection, but improve over time. After COVID-19 infection, CT features are suggestive of persistent parenchymal lung injury, in keeping with a post-COVID-19 interstitial lung syndrome. It is yet to be determined if this is a regressive or progressive disease.

Updated review of reported cases of reactive airways dysfunction syndrome

BACKGROUND

A previous systematic review of the diagnosis of reactive airways dysfunction syndrome (RADS), undertaken from 1985 to 2004, found a lack of standardization of case reporting, thus misattribution of symptoms can occur.

AIMS

We aimed to update the systematic review, update the list of reported causes and see whether a more structured approach to reporting has been adopted.

METHODS

We undertook a systematic literature review, using the databases EMBASE and Ovid MEDLINE, with search terms 'reactive airways dysfunction syndrome' or 'asthma AND acute irritant', and reported according to PRISMA guidelines. We included papers and abstracts published from January 2005 to September 2019, and articles were grouped by the presence or absence of diagnostic features: 'definite' RADS (met Brooks' criteria) or 'possible' RADS (Brooks' criteria not met or insufficient data). We collected demographic and diagnostic data for cases, where given.

RESULTS

Eleven papers and six conference abstracts met the inclusion criteria, 13 of which were case series or reports, and comprised 752 cases in total; seven articles met Brooks' criteria for RADS diagnosis. A variety of agents were implicated, with chlorine or chlorine-releasing molecules most frequently reported.

CONCLUSIONS

A lack of standardized reporting of RADS remains. The majority of published articles and conference abstracts either do not meet, or contain insufficient data to judge against, Brooks' criteria, particularly in relation to onset of symptoms and bronchial hyper-reactivity or variability of airflow obstruction. Some novel agents are described, in keeping with recognized structural taxonomies.

An update on hypersensitivity pneumonitis: what a clinician wants to know

PURPOSE OF REVIEW

A recent international collaboration has updated the clinical definition and diagnostic recommendations for hypersensitivity pneumonitis, focusing on fibrotic and non-fibrotic phenotypes. However, how these transfer to clinical practice and their impact upon clinical management and prognosis of hypersensitivity pneumonitis is unclear. This review will focus on recent advances in the understanding of the clinical aspects of hypersensitivity pneumonitis, predominantly its epidemiology, diagnosis, classification and treatment.

RECENT FINDINGS

Hypersensitivity pneumonitis is a rare disease within the general population, with variable geographical incidence because of environmental, cultural and occupational factors. Confidence in diagnosis relies upon the presence of clinical features with a temporal relationship to an associated exposure, radiological and histopathological features, bronchiolo-alveolar lavage lymphocytosis and precipitating antibodies/specific immunoglobulin G to antigens. Although emerging evidence regarding nintedanib use in progressive fibrotic interstitial lung disease is promising, the majority of therapies (corticosteroids and immunosuppressive agents) used traditionally in hypersensitivity pneumonitis lack a robust evidence base.

SUMMARY

With a clear definition of fibrotic and nonfibrotic hypersensitivity pneumonitis phenotypes now established, clinical research trials (predominantly randomized controlled trials) should clarify and resolve the discussion regarding antigen avoidance, corticosteroid therapy, immunosuppressive therapy and antifibrotic therapy in fibrotic and nonfibrotic subtypes of hypersensitivity pneumonitis.

Role of NH(2)- and COOH-terminal domains of the P protein of human parainfluenza virus type 3 in transcription and replication

The phosphoproteins (P proteins) of paramyxoviruses play a central role in transcription and replication of the viruses by forming the RNA polymerase complex L-P and encapsidation complex (N-P) with nucleocapsid protein (N) and binding to N protein-encapsidated genome RNA template (N-RNA template). We have analyzed the human parainfluenza virus type 3 (HPIV3) P protein and deletion mutants thereof in an in vitro transcription and in vivo replication system. The in vitro system utilizes purified N-RNA template and cell extract containing L and P proteins coexpressed via plasmids using a recombinant vaccinia virus expression system. The in vivo system takes advantage of minigenome replication, which measures luciferase reporter gene expression from HPIV3 minigenomes by viral proteins in a recombinant vaccinia virus expression system. These studies revealed that the C-terminal 20-amino-acid region of P is absolutely required for transcription in vitro and luciferase expression in vivo, suggesting its critical role in viral RNA synthesis. The N-terminal 40-amino-acid region, on the other hand, is essential for luciferase expression but dispensable for transcription in vitro. Consistent with these findings, the C-terminal domain is required for binding of P protein to the N-RNA template involved in both transcription and replication, whereas the N-terminal domain is required for the formation of soluble N-P complex involved in encapsidation of nascent RNA chains during replication. Coimmunoprecipitation analysis showed that the P protein forms a stable homooligomer (perhaps a trimer) that is present in L-P and N-P complexes in the higher oligomeric forms (at least a pentamer). Interestingly, coexpression of a large excess of N- or C-terminally deleted P with wild-type P had no effect on minigenome replication in vivo, notwithstanding the formation of heterooligomeric complexes. These data indicate that P protein with a deleted terminal domain can function normally within the P heterooligomeric complex to carry out transcription and replication in vivo.

Phosphorylation of Sendai virus phosphoprotein by cellular protein kinase C zeta

The phosphoproteins (P) of nonsegmented negative strand RNA viruses are viral RNA polymerase subunits involved in both transcription and replication during the virus life cycle. Phosphorylation of P proteins in several negative strand RNA viruses by specific cellular kinases was found to be required for P protein function. In the present study, using bacterially expressed unphosphorylated P protein of Sendai virus, a mouse parainfluenza virus, we have shown that the major cellular kinase that phosphorylates P protein in vitro is biochemically and immunologically indistinguishable from protein kinase C (PKC) zeta isoform. PKC zeta was packaged into the Sendai virion and remained associated with purified viral ribonucleoprotein, where it phosphorylated both the P and the nucleocapsid protein in vitro. When PKC zeta-specific inhibitory pseudosubstrate peptide was introduced into LLC-MK2 cells prior to Sendai virus infection, production of progeny virus was dramatically attenuated, and kinetic analysis revealed that primary transcription was repressed. These data indicate that phosphorylation of the Sendai virus P protein by PKC zeta plays a critical role in the virus life cycle.

Phosphorylation of canine distemper virus P protein by protein kinase C-zeta and casein kinase II

Transcription by nonsegmented negative-strand RNA viruses is mediated by the viral RNA-dependent RNA polymerase and transcriptional cofactor P. The P protein is activated by phosphorylation, an event initiated by cellular kinases. The kinase used differs among this group of RNA viruses; vesicular stomatitis virus and respiratory syncytial virus utilize casein kinase II (CKII), whereas human parainfluenza virus type 3 utilizes PKC isoform zeta (PKC-zeta) for activation of its P protein. To identify the cellular kinase(s) involved in the phosphorylation of the canine distemper virus (CDV) P protein, we used recombinant CDV P in phosphorylation assays with native kinase activities present in CV1 cell extracts or purified CKII and PKC isoforms. Here, we demonstrate that the CDV P protein is phosphorylated by two cellular kinases, where PKC-zeta has the major and CKII the minor activities. In contrast, the P protein of another member of the morbillivirus genus, measles virus, is phosphorylated predominantly by CKII, whereas PKC-zeta has only minor activity. Selective inhibition of PKC-zeta activity within CV1 cells eliminated permissiveness to CDV replication, indicating an in vivo role for PKC-zeta in the virus replication cycle. The broad tissue expression of PKC-zeta parallels the pantropic nature of CDV infections, suggesting that PKC-zeta activity is a determinant of cellular permissiveness to CDV replication.

Human parainfluenza virus type 3 phosphoprotein: identification of serine 333 as the major site for PKC zeta phosphorylation

The human parainfluenza virus type 3 P protein is an RNA polymerase subunit involved in both transcription and replication during the life cycle of the virus. Our laboratory has recently shown that the P protein is phosphorylated both in vitro and in vivo by the cellular protein kinase C (PKC) isoform zeta and that this phosphorylation is essential for viral replication. To identify the site(s) of phosphorylation, we have used CNBr cleavage, phosphoamino acid analysis, and two-dimensional tryptic peptide mapping of the in vitro and in vivo phosphorylated P protein. We demonstrate that when bacterially expressed unphosphorylated P is labeled in vitro with either commercial PKC or purified recombinant PKC zeta P protein has one major phosphorylation site. By site-directed mutagenesis of PKC consensus sites in the P protein, the primary phosphorylation site is found to be Ser 333. The same site appeared to be modified when viral P protein was phosphorylated in vitro by the PKC packaged within the virion and in the P protein of progeny virion labeled in vivo.

Common replication strategies emerging from the study of diverse groups of positive-strand RNA viruses

Studies using brome mosaic virus (BMV), Sindbis virus and poliovirus have provided evidence that disparate groups of plant and animal positive strand RNA viruses have remarkably similar replication strategies. The conservation of several functional domains within virus-encoded nonstructural proteins implies that, although the precise character of these and interacting host components varies for each virus, they employ similar mechanisms for RNA replication. For (+) strand replication, similarities in cis-acting sequence motifs and RNA secondary structures within 5' termini of genomic (+) strands have been identified and have been shown to participate in binding of host factors. The model presented for replication of BMV RNA suggests that binding of these factors to internal control region (ICR) sequence motifs in the double-stranded replication intermediate releases a single-stranded 3' terminus on the (-) strand that may be essential for initiation of genomic (+) strand synthesis. ICR sequences internal to the BMV genome were also found to be required for efficient replication. Asymmetric production of excess genomic (+) over (-) strand RNA, characteristic of all (+) strand viruses, may be accomplished through transition of the replicase from competence for (-) to (+) strand synthesis by the recruitment of additional host factors.

Interference with brome mosaic virus replication by targeting the minus strand promoter

Sense and antisense strategies for interfering with the replication of brome mosaic virus (BMV) were examined. The effects of 200 nucleotide-long sense and antisense transcripts, corresponding to the viral 3' end (-) strand promoter, on the accumulation of progeny viral RNAs were studied by co-inoculation with wildtype BMV RNAs. Progeny accumulation in barley protoplasts transfected with either sense or antisense transcripts of the (-) strand promoter and BMV RNAs-1 and -2 was decreased by more than 90%, and by 60 to 80% when RNA-3 was also present. This trans interference was concentration-dependent, and reduced both (+) and (-) strand progeny accumulation to a similar extent. The appearance of complementary (-) strands indicated that sense interfering transcripts could serve as templates for (-) strand synthesis, and the use of deletion mutants revealed that the observed interference was in part mediated by this template activity. The reproducibility of the protoplast assay used here allows rapid evaluation of interference strategies and comparisons to be made of alternative approaches to engineered resistance. The results presented here suggest that targeting viral (-) strand promoters with sense and antisense transcripts may be an effective method for engineering plant resistance to viral infection.

Minus sense transcripts of brome mosaic virus RNA-3 intercistronic region interfere with viral replication

Interference with virus replication through the use of defective viral sequences is providing new insight to replication strategies and novel approaches for induced resistance. Because replication of brome mosaic virus (BMV) is potentiated by the intercistronic region of RNA-3, we examined the effect of adding various (-)sense RNAs corresponding to this region in co-transfections with wild type BMV RNAs. Progeny accumulation in barley protoplasts transfected with RNAs 1+2 was decreased by 90% in the presence of (-)RNA-3 delta HindIII, the longest (-)sense transcript tested, and by 85% when RNA-3 was also present. This trans interference was concentration dependent, and the use of deletion derivatives of (-)RNA-3 delta HindIII revealed that previously identified regulatory sequences within the intercistronic region were responsible for the observed interference. These deletion mutants were found to be of differing stabilities and several served as effective substrates for host-encoded polymerase to yield complementary (+)strands. Indeed, it is possible that the copying of viral RNA by the host polymerase serves as a hybrid arrest mechanism for discriminating against viral RNA functions. However, neither the ability of these sequences to serve as templates for host polymerase nor their (+)strand products contributed to the interference phenomenon, which may provide a new approach for engineering resistance to viral infection.

Regulation of (+):(-)-strand asymmetry in replication of brome mosaic virus RNA

Transfection of barley protoplasts with brome mosaic virus (BMV) RNAs 1 + 2 in the absence of RNA-3 yielded a molar ratio for (+):(-)-strand progeny at 24 hr postinoculation near unity, whereas over 100-fold more (+)- than (-)-strand progeny accumulated in its presence. The presence of RNA-3 enhanced total (+)-strand RNA production 205-fold and that of RNAs 1 + 2 by 29-fold. In contrast, total (-)-strand RNA accumulation decreased by 68% and that for (-)RNAs 1 + 2 by 79% in the presence of RNA-3. Transfections containing an RNA-3 mutant (Gsgi----U RNA-3) that is incapable of yielding RNA-4 as a result of a single nucleotide substitution at the subgenomic RNA initiation site yielded only 66% of the (+):(-) asymmetry seen in the presence of wild-type RNA-3. Only 1.8-fold excess of (+)-over (-)-strand production was obtained for transfections that included delta SGP RNA-3, a deletion that includes the subgenomic promoter core and extends 43 nt into the RNA-4 sequence. Transfections containing RNA-3 mutants bearing frameshifts or deletions in the coat protein cistron yielded levels of asymmetry similar to those seen for Gsgi----U RNA-3. These findings implicate the subgenomic promoter and other sequences in the intercistronic region of RNA-3 as the primary determinants of asymmetric replication, although the coat protein may be an additional factor enhancing the accumulation of (+)-strand RNA.

Analysis of RNA stability and (-) strand content in viral infections using biotinylated RNA probes

Non-radioactive biotinylated RNA probes specific for plus (+) and minus (-) sense RNAs of brome mosaic virus (BMV) were synthesized in vitro from a plasmid bearing a 200 base pair fragment complementary to the 3' terminus of each of the three genomic RNAs of the virus. Using virion RNAs isolated from BMV infected barley plants, the sensitivity of biotinylated RNAs as hybridization probes was compared with that of 32P-labeled probes in Northern hybridization assays. Although the sensitivity of biotinylated and 32P-labeled probes is similar (approximately 5 pg), the time required to detect the RNA bands was much less than for autoradiography; (-) sense RNAs could be detected in 30 min whereas 48 h or more were required by autoradiography. The value of biotinylated probes for following RNA stability was exemplified by the detection of supplied inocula in protoplasts 24 h post-inoculation. Quantitation of relative accumulation of progeny (+) and (-) sense RNAs by densitometry of the Northern blots probed with biotinylated RNAs paralleled that of radiolabeled probes. The application of these probes was extended to the detection of RNAs in barley protoplasts and BMV infected plant sap by dot hybridization. In these tests, viral RNAs were detected in as few as 250 protoplasts and sap dilutions up to 1:2000. The merits of these non-radioactive probes in monitoring the replication events by the detection and quantitation of mutant progeny RNAs of BMV are discussed.

Histochemical diagnosis of Hirschsprung disease

A histochemical staining technique for detection of acetylcholinesterase (AChE) in rectal suction biopsies was compared with the presence or absence of ganglion cells in full-thickness or suction biopsies for the diagnosis of Hirschsprung disease (HD) in infants and children. Biopsies from 55 of 58 children were adequate for both the AChE assay and routine pathologic examination for ganglion cells. Two patterns of AChE staining were noted. With pattern A, prominent nerve fibers staining for AChE were seen throughout the muscularis mucosa and the lamina propria. With pattern B, similar fibers were seen only in the muscularis mucosa and the areas of lamina propria that were immediately adjacent. No "false-negative" AChE staining reactions were found in patients with HD. No "false-positive" reactions showing pattern A were found. This pattern was diagnostic for HD. Three false-positive reactions were found showing pattern B in patients with conditions other than HD. Among 22 patients with HD, 19 were males and three were females. Pattern A occurred in all age groups and in both sexes. Pattern B in patients with HD was seen exclusively in male infants 1 month of age or less. Experience suggests that the AChE staining of rectal suction biopsies is an excellent screening test for HD in infants and children. If pattern B is encountered, however, the specimen should be examined by routine pathologic techniques for the presence of submucosal ganglion cells.

Cell-mediated hypersensitivity to mite antigens in atopic dermatitis

Cell-mediated hypersensitivity (CMH) to house dust mite antigens, as determined by increased DNA synthesis after coculture of mononuclear cells with Dermatophagoides farinae extract, was demonstrated in 11 of 16 children with atopic dermatitis (AD) as compared with two of 14 control subjects. Patient and control responses peaked at the same antigen dose (12.4 micrograms of mite protein per 10(5) cells). Patient responses were significantly greater at all mite protein concentrations. The increased DNA synthesis of stimulated cells was demonstrated to be a T-cell response in the one patient in whom T-cell-enriched cultures were studied. There was no relationship between CMH and lgE-mediated hypersensitivity to D farinae in the patient group. It is suggested that AD is associated with CMH reactions to allergens and that antigen competition may be involved in the reduced CMH responses to mitogens and antigens noted by other investigators.

Vasculitis involving muscle associated with Crohn's colitis

A case of Crohn's colitis is described in a patient who demonstrated multiple extraintestinal complications, including erythema nodosum, pyoderma gangrenosum, and aphthous oral ulcerations. Our patient simultaneously developed an unusual vasculitis in muscle. Small vessels were affected by necrosis, and polymorphonuclear leukocyte infiltration was appreciated. Leukocytoclastic was suggested by these features and the additional finding of small amounts of nuclear debris. A strong immunofluorescence to antihuman C3 was demonstrated in the affected vessel walls. We did not find circulating IgG immune complexes in serum with the Raji cell assay. The implication of the finding of leukocytoclastic vasculitis in muscle, associated with Crohn's colitis, is discussed.

Anhidrotic ectodermal dysplasia with transient hypogammaglobulinemia

An 8-month-old white boy with anhidrotic ectodermal dysplasia (AED) who was referred to the North Carolina Baptist Hospital because of recurrent respiratory infections and hypogammaglobulinemia is presented. His mother had partial expression of AED suggesting x-linked recessive inheritance in this family. She was incidentally given oral glucocorticoids during pregnancy for the treatment of chronic urticaria. The patient's serum immunoglobulins G, A and M were low at 8 months but normal by 15 months of age, and immunologic evaluation failed to show a defect in antibody production or cell-mediated immunity. Although rare, the diagnosis of AED must be considered in infant boys with recurrent fever and respiratory infections. The diagnostic features of the disease may be subtle in young child prior to the eruption of the characteristic peg-shaped teeth.

Oxidative metabolism of the human eosinophil

We have compared the oxidative metabolism of human eosinophils (80%-90% purity) to that of neutrophils. Hexose monophosphate (HMP) shunt activity of eosinophils was higher than that of neutrophils under either resting or phagocytizing conditions. Eosinophil HMP shunt activity also was stimulated by phorbol myristate acetate, a membrane-active agent. Eosinophils showed a marked incorporation of 125I into trichloroacetic acid-insoluble material under resting conditions, which increased markedly during phagocytosis. Eosinophils likewise showed a greater reduction of nitroblue tetrazolium dye during phagocytosis than did neutrophils. Measurement of other parameters of oxidative metabolism indicated that eosinophils generated superoxide anion following phagocytosis and also elicited a burst of chemiluminescence similar to that observed during phagocytosis by neutrophils. Measurement of NADPH oxidase activity demonstrated that this enzyme was 3-6 times more active in fractions isolated from eosinophils than in corresponding fractions isolated from neutrophils; this was observed over a range of substrate concentrations. The eosinophil enzyme sedimented differently than the neutrophil enzyme with differential centrifugation; neither showed sedimentation characteristics of peroxidase. These data indicate that eosinophils possess a similar, although in some ways more potent, oxidative burst than neutrophils and are consistent with a role for NADPH oxidase in the initiation of that burst.

ABO hemolytic disease in Puerto Rico and North Carolina

A prospective study was carried out at the University of Puerto Rico Hospital (UPRH) and at the North Carolina Baptist Hospital (NCBH) in order to establish the incidence of ABO hemolytic disease (ABO HD) in the two populations and to determine the relationship of intestinal parasitic infection of the mother to ABO HD in the infant. The incidence of ABO HD among UPRH at risk pregnancies (type O mother with type A or B infant) was 28.3% or 1 in 3.5 as compared with 18.4% or 1 in 5.4 of NCBH at risk pregnancies (P less than .05). Indirect Coombs' tests in cord sera, representing the passive transfer from mother to fetus of antibodies directed toward antigens on the infants' erythrocytes, were positive in 58.8% of UPRH at risk infants as opposed to 40.4% of NCBH at risk infants (P less than .001). Maternal isohemagglutinin titers at term were higher in type O UPRH mothers than in type O NCBH mothers (P less than .01). A relationship between helminth parasitic infection of the mother and ABO HD in the infant was suspected but not proved.

Evaluation of visceral larva migrans by radioimmunoassay systems

A 9-year-old child with miliary pulmonary infiltrates, eosinophilia, and hyperimmunoglobulinemia E recovered rapidly cover a four-week period. Subsequent analysis of serum samples by a solid phase radioimmunoassay technique demonstrated IgM, IgE, and IgG antibodies to Ascaris suum antigen which declined following the acute phase of the illness in parallel with a decline in serum IgM, IgE, and IgG concentrations. Precipitating antibodies in serum against Ascaris antigen were demonstrated. The diagnosis is considered to be toxocariasis or ascariasis. The application of sensitive radioimmunoassay techniques of this type should provide a method of earlier diagnosis and the demonstration of rapidly changing antibody levels a method of confirming the diagnosis in parasitic diseases.

Visceral larva migrans: Immunoglobulins, precipitating antibodies and detection of IgG and IgM antibodies against Ascaris antigen

Serum samples from ten children with visceral larva migrans were evaluated by analysis of: immunoglobulin concentrations, precipitin reactions against Toxocara and Ascaris antigens and blood group substances, and IgM and IgG activity against Ascaris antigen by radioimmunoassay (RIA). The elevated concentrations of serum IgE and IgG and the positive precipitin reactions which occurred in some cases are an aid in diagnosis but were not consistently present. Serum IgM concentrations were elevated in all cases. IgM or IgG antibodies against Ascaris suum antigen were detected in all cases by a solid phase RIA technique. Radioimmunoassay techniques of this type may provide a superior method of diagnosis, particularly if used with serial serum samples which demonstrate changing levels of antibodies.

Lymphopenic immunologic deficiency in identical twins: lymphocyte allografting and graft-versus-host disease following treatment with albumin-gradient-separated paternal bone marrow cells

The clinical, immunologic and pathologic features of the first recorded examples of lymphopenic immunologic deficiency in twins are presented. Eleven-month-old male identical twin infants were found to be severely lymphopenic and lacked demonstrable cell-mediated immunity and antibody formation. Each first-degree relative differed from the probands by one chromosome at the major human histocompatibility locus, HL-A. Because of their rapidly deteriorating clinical conditions, allogeneic bone marrow transplantation was undertaken. Circumvention of graft-versus-host disease was attempted by separation of donor bone marrow cells on a discontinuous-albumin-gradient and administration of only 5×10⁶ immature nucleated marrow cells per kilogram infant body weight. Additionally, immunologic enhancement was attempted by pretreating the infants with human isoantisera to identifiable infant HL-A antigens not present in the marrow donor. Paternal lymphocyte allografting occurred, as demonstrated by lymphocyte cytotoxicity testing, but both infants succumbed to graft-versus-host disease at the end of 3 weeks.