A Retrospective Analysis of 2-Year Follow-Up of Patients with Incidental Findings of Sarcoidosis.

INTRODUCTION: Sarcoidosis is a multi-system granulomatous disease most commonly involving the lungs. It may be incidentally diagnosed during imaging studies for other conditions or non-specific symptoms. The appropriate follow-up of incidentally diagnosed asymptomatic stage 1 disease has not been well defined. OBJECTIVE: To define the clinical course of incidentally diagnosed asymptomatic stage 1 sarcoidosis and propose an algorithm for the follow-up of these patients. METHODOLOGY: A retrospective case note analysis was performed of all EBUS-TBNA (endobronchial ultrasound-guided transbronchial needle aspiration)-confirmed cases of stage 1 sarcoidosis presenting incidentally to Bristol and Liverpool Interstitial Lung Disease services. Clinical history, serology results, imaging scans, and lung function parameters were examined at baseline, 12, and 24 months. A cost analysis was performed comparing the cost of the current 2-year follow-up guidance to a 1 year follow-up period. RESULTS: Sixty-seven patients were identified as the final cohort. There was no significant change in the pulmonary function tests over the two-year follow-up period. Radiological disease stability was observed in the majority of patients (58%, n = 29), and disease regression was evidenced in 40% (n = 20) at 1 year. Where imaging was performed at 2 years, the majority (69.8%, n = 37) had radiological evidence of disease regression, and 30.2% (n = 16) showed radiological evidence of stability. All patients remained asymptomatic and did not require therapeutic intervention over the study period. CONCLUSIONS: Our results show that asymptomatic patients with incidental findings of thoracic lymph nodal non-caseating granulomas do not progress over a 2-year period. Our results suggest that the prolonged secondary-care follow-up of such patients may not be necessary. We propose that these patients are followed up for 1 year with a further year of patient-initiated follow-up (PIFU) prior to discharge.

Multi-center evaluation of baseline neutrophil-to-lymphocyte (NLR) ratio as an independent predictor of mortality and clinical risk stratifier in idiopathic pulmonary fibrosis.

Background: Idiopathic pulmonary fibrosis (IPF) is a progressive, fatal disorder with a variable disease trajectory. The aim of this study was to assess the potential of neutrophil-to-lymphocyte ratio (NLR) to predict outcomes in IPF. Methods: We adopted a two-stage discovery (n = 71) and validation (n = 134) design using patients from the UCL partners (UCLp) cohort. We then combined discovery and validation cohorts and included an additional 794 people with IPF, using real-life data from 5 other UK centers, to give a combined cohort of 999 patients. Data were collected from patients presenting over a 13-year period (2006-2019) with mean follow up of 3.7 years (censoring: 2018-2020). Findings: In the discovery analysis, we showed that high values of NLR (>/ = 2.9 vs < 2.9) were associated with increased risk of mortality in IPF (HR 2.04, 95% CI 1.09-3.81, n = 71, p = 0.025). This was confirmed in the validation (HR 1.91, 95% CI 1.15-3.18, n = 134, p = 0.0114) and combined cohorts (HR 1.65, n = 999, 95% CI 1.39-1.95; p < 0·0001). NLR correlated with GAP stage and GAP index (p < 0.0001). Stratifying patients by NLR category (low/high) showed significant differences in survival for GAP stage 2 (p < 0.0001), however not for GAP stage 1 or 3. In a multivariate analysis, a high NLR was an independent predictor of mortality/progression after adjustment for individual GAP components and steroid/anti-fibrotic use (p < 0·03). Furthermore, incorporation of baseline NLR in a modified GAP-stage/index, GAP-index/stage-plus, refined prognostic ability as measured by concordance (C)-index. Interpretation: We have identified NLR as a widely available test that significantly correlates with lung function, can predict outcomes in IPF and refines cohort staging with GAP. NLR may allow timely prioritisation of at-risk patients, even in the absence of lung function. Funding: Breathing Matters, GSK, CF Trust, BLF-Asthma, MRC, NIHR Alpha-1 Foundation.

Safety, tolerability, and efficacy of pirfenidone in patients with rheumatoid arthritis-associated interstitial lung disease: a randomised, double-blind, placebo-controlled, phase 2 study.

BACKGROUND: Interstitial lung disease is a known complication of rheumatoid arthritis, with a lifetime risk of developing the disease in any individual of 7·7%. We aimed to assess the safety, tolerability, and efficacy of pirfenidone for the treatment of patients with rheumatoid arthritis-associated interstitial lung disease (RA-ILD). METHODS: TRAIL1 was a randomised, double-blind, placebo-controlled, phase 2 trial done in 34 academic centres specialising in interstitial lung disease in four countries (the UK, the USA, Australia, and Canada). Adults aged 18-85 years were eligible for inclusion if they met the 2010 American College of Rheumatology and European Alliance of Associations for Rheumatology criteria for rheumatoid arthritis and had interstitial lung disease on a high-resolution CT scan imaging and, when available, lung biopsy. Exclusion criteria include smoking, clinical history of other known causes of interstitial lung disease, and coexistant clinically significant COPD or asthma. Patients were randomly assigned (1:1) to receive 2403 mg oral pirfenidone (pirfenidone group) or placebo (placebo group) daily. The primary endpoint was the incidence of the composite endpoint of a decline from baseline in percent predicted forced vital capacity (FVC%) of 10% or more or death during the 52-week treatment period assessed in the intention-to-treat population. Key secondary endpoints included change in absolute and FVC% over 52 weeks, the proportion of patients with a decline in FVC% of 10% or more, and the frequency of progression as defined by Outcome Measures in Rheumatoid Arthritis Clinical Trials (OMERACT) in the intention-to-treat population. This study is registered with ClinicalTrials.gov, NCT02808871. FINDINGS: From May 15, 2017, to March 31, 2020, 231 patients were assessed for inclusion, of whom 123 patients were randomly assigned (63 [51%] to the pirfenidone group and 60 [49%] to the placebo group). The trial was stopped early (March 31, 2020) due to slow recruitment and the COVID-19 pandemic. The difference in the proportion of patients who met the composite primary endpoint (decline in FVC% from baseline of 10% or more or death) between the two groups was not significant (seven [11%] of 63 patients in the pirfenidone group vs nine [15%] of 60 patients in the placebo group; OR 0·67 [95% CI 0·22 to 2·03]; p=0·48). Compared with the placebo group, patients in the pirfenidone group had a slower rate of decline in lung function, measured by estimated annual change in absolute FVC (-66 vs -146; p=0·0082) and FVC% (-1·02 vs -3·21; p=0·0028). The groups were similar with regards to the decline in FVC% by 10% or more (five [8%] participants in the pirfenidone group vs seven [12%] in the placebo group; OR 0·52 [95% CI 0·14-1·90]; p=0·32) and the frequency of progression as defined by OMERACT (16 [25%] in the pirfenidone group vs 19 [32%] in the placebo group; OR 0·68 [0·30-1·54]; p=0·35). There was no significant difference in the rate of treatment-emergent serious adverse events between the two groups, and there were no treatment-related deaths. INTERPRETATION: Due to early termination of the study and underpowering, the results should be interpreted with caution. Despite not meeting the composite primary endpoint, pirfenidone slowed the rate of decline of FVC over time in patients with RA-ILD. Safety in patients with RA-ILD was similar to that seen in other pirfenidone trials. FUNDING: Genentech.

A multidisciplinary approach to the diagnosis of antisynthetase syndrome.

Antisynthetase syndrome is a subtype of idiopathic inflammatory myopathy, strongly associated with the presence of interstitial lung disease. Diagnosis is made by identifying myositis-specific antibodies directed against aminoacyl tRNA synthetase, and relevant clinical and radiologic features. Given the multisystem nature of the disease, diagnosis requires the careful synthesis of subtle clinical and radiological features with the interpretation of specialized autoimmune serological testing. This is provided in a multidisciplinary environment with input from rheumatologists, respiratory physicians, and radiologists. Differentiation from other idiopathic interstitial lung diseases is key; treatment and prognosis differ between patients with antisynthetase syndrome and idiopathic interstitial lung disease. In this review article, we look at the role of the multidisciplinary team and its individual members in the initial diagnosis of the antisynthetase syndrome, including the role of physicians, radiologists, and the wider team.

Use of peripheral neutrophil to lymphocyte ratio and peripheral monocyte levels to predict survival in fibrotic hypersensitivity pneumonitis (fHP): a multicentre retrospective cohort study.

The factors determining disease course and survival in fibrotic hypersensitivity pneumonitis (fHP) have not been fully elucidated.The aim of this study was to describe the characteristics of patients with fHP in a real-world cohort and investigate factors associated with worse outcomes. We aimed to explore the use of neutrophil to lymphocyte ratio (NLR) and peripheral blood monocyte levels in predicting mortality. METHODS: A retrospective, multicentre, observational UK cohort study. RESULTS: Patients with fHP were significantly younger than those with idiopathic pulmonary fibrosis (IPF) (median age fHP 73 vs IPF 75 years) and were much more likely to be woman (fHP 61% vs IPF 26%). In almost half of all fHP cases (49%, n=104/211), no causative antigen was identified from either the history or specific antigen testing. Overall, fHP was associated with a better survival than IPF, although median survival of both groups was poor (fHP 62 months vs IPF 52 months).IPF survival in patients with a high NLR was significantly lower than those with a low NLR (44 vs 83 months). A monocyte count ≥0.95 K/uL also predicted significantly poorer outcomes for patients with IPF compared with <0.95 K/uL (33 vs 57 months). In contrast, NLR and monocyte count did not predict survival in the fHP cohort. CONCLUSIONS: Although fHP has a statistically lower mortality than IPF, absolute survival time of both conditions is poor. High baseline NLR and absolute monocyte counts predict worse survival in IPF but not in fHP, highlighting the potential for divergence in their pathogenic mechanisms.

Long-term nitrofurantoin: an analysis of complication awareness, monitoring, and pulmonary injury cases.

BACKGROUND: Long-term nitrofurantoin (NF) treatment can result in pulmonary and hepatic injury. Current guidelines do not outline the type or frequency of monitoring required for detection of these injuries. AIM: To assess 1) awareness of NF complications among prescribers; 2) monitoring practice; and 3) to describe the pulmonary sequelae of NF-related complications. DESIGN & SETTING: Evaluation of prescribing habits by questionnaires and review of GP databases, and case-note review in secondary care. METHOD: The following study procedures were undertaken: 1) an electronic questionnaire was distributed to prescribers, interrogating prescribing and monitoring practices, and awareness of complications; 2) an analysis was undertaken (June-July 2020) of NF monitoring among GPs in the local clinical commissioning group (CCG); and 3) a case review was carried out of patients diagnosed with NF-induced interstitial lung disease (NFILD) at the interstitial lung disease (ILD) centre (2014-2020). RESULTS: A total of 125 prescribers of long-term NF responded to the questionnaire (82.4% GPs; 12.0% urologists). Many were unaware of the potential for liver (42.4%) and lung (28.0%) complications; 40.8% and 52.8% never monitored for these, respectively. Only 53.3% of urologists believed themselves responsible for arranging monitoring, while nearly all GPs believed this to be the prescriber's responsibility (94.2%). One-third of all responders considered current British National Formulary (BNF) guidelines 'not at all sufficient/clear', with mean clarity scoring of 2.2/5. Among patients with NFILD (n = 46), NF had been prescribed most often (69.6%) for treatment of recurrent UTI and 58.6% (n = 27) were prescribed for >6 months. On withdrawal of the medication 61.4% displayed resolution (completely or minimal fibrosis), while 15.9% of patients had progressive lung fibrosis. CONCLUSION: NF can cause marked or irreversible lung complications and there is currently a shortfall in awareness and monitoring. Existing monitoring guidelines should be augmented.

Clinicoserological features of antisynthetase syndrome (ASyS)-associated interstitial lung disease presenting to respiratory services: comparison with idiopathic pulmonary fibrosis and ASyS diagnosed in rheumatology services.

INTRODUCTION: Antisynthetase syndrome (ASyS) is a rare autoimmune connective tissue disease (CTD), associated with autoantibodies targeting tRNA synthetase enzymes, that can present to respiratory (interstitial lung disease (ILD)) or rheumatology (myositis, inflammatory arthritis and systemic features) services. The therapeutic management of CTD-associated ILD and idiopathic pulmonary fibrosis (IPF) differs widely, thus accurate diagnosis is essential. METHODS: We undertook a retrospective, multicentre observational cohort study designed to (1) evaluate differences between ASyS-associated ILD with IPF, (2) phenotypic differences in patients with ASyS-ILD presenting to respiratory versus rheumatology services, (3) differences in outcomes between ASySassociated with Jo-1 versus non-Jo-1 autoantibodies and (4) compare long-term outcomes between these groups. RESULTS: We identified 76 patients with ASyS-ILD and 78 with IPF. Patients with ASyS were younger at presentation (57 vs 77 years, p<0.001) with a female predominance (57% vs 33%, p=0.006) compared with IPF. Cytoplasmic staining on indirect immunofluorescence was a differentiating factor between ASyS and IPF (71% vs 0%, p<0.0001). Patients with ASyS presenting initially to respiratory services (n=52) had a higher prevalence of ASyS non-Jo-1 antibodies and significantly fewer musculoskeletal symptoms/biochemical evidence of myositis, compared with those presenting to rheumatology services (p<0.05), although lung physiology was similar in both groups. There were no differences in high-resolution CT appearances or outcomes in those with Jo-1 versus non-Jo-1 ASyS-ILD. CONCLUSIONS: Extended autoimmune serology is needed to evaluate for ASyS autoantibodies in patients presenting with ILD, particularly in younger female patients. Musculoskeletal involvement is common in ASyS (typically Jo-1 autoantibodies) presenting to rheumatology but the burden of ILD is similar to those presenting to respiratory medicine.

Patient outcomes after hospitalisation with COVID-19 and implications for follow-up: results from a prospective UK cohort.

The longer-term consequences of SARS-CoV-2 infection are uncertain. Consecutive patients hospitalised with COVID-19 were prospectively recruited to this observational study (n=163). At 8-12 weeks postadmission, survivors were invited to a systematic clinical follow-up. Of 131 participants, 110 attended the follow-up clinic. Most (74%) had persistent symptoms (notably breathlessness and excessive fatigue) and limitations in reported physical ability. However, clinically significant abnormalities in chest radiograph, exercise tests, blood tests and spirometry were less frequent (35%), especially in patients not requiring supplementary oxygen during their acute infection (7%). Results suggest that a holistic approach focusing on rehabilitation and general well-being is paramount.

South-West of England's Experience of the Safety and Tolerability Pirfenidone and Nintedanib for the Treatment of Idiopathic Pulmonary Fibrosis (IPF).

Purpose: Pirfenidone and nintedanib are two novel antifibrotic agents licensed for the treatment IPF. Prior to being approved for use in England for patients with FVC >50% and <80%, these were made available for all IPF patients under the Mild Patient Program (MPP) and Patient In Need Scheme (PIN). Prescribing of these medications is restricted to specialist centers. We sought to characterize the population of patients prescribed antifibrotics and determine the drug tolerability of these medications in the Northern hub of the Southwest of England regional ILD network. Methods: A retrospective analysis of all patients treated with antifibrotics between August 2012 and July 2017 was undertaken. Baseline characteristics including patient demographics and pulmonary physiology, in addition to drug tolerability and reasons for treatment cessation were collated. Data were compared using unpaired student's t-test, Chi-squared, Mann-Whitney rank sum or ANOVA as appropriate. Logistic regression analysis evaluated clinical characteristics associated with discontinuation of pirfenidone therapy. P < 0.05 was considered statistically significant. Findings: A total of 164 patients, all with consensus diagnoses of IPF, were identified. Of these, 70.1% (115/164) received pirfenidone as their initial therapy. Baseline age, gender and pulmonary physiology did not differ significantly between groups. Drug discontinuation occurred most commonly due to adverse drug reactions events (ADRs) for both pirfenidone [40.0% (46/115)] and nintedanib [16.3% (8/49)]. Anorexia, rash and gastrointestinal disturbance were reported most commonly as the reason for cessation of pirfenidone; anorexia, nausea and weight loss for nintedanib. Duration of therapy prior to discontinuation because of ADRs did not differ significantly between medication groups but patients with a baseline FVC < 65% predicted, had a significantly shorter duration of pirfenidone prior to discontinuation due to ADRs, compared to those with a FVC 65-80% predicted. Multivariate logistic regression did not identify any independent baseline characteristics that predicted discontinuation of pirfenidone therapy prior to 52 weeks. Implications: Idiopathic pulmonary fibrosis (IPF) patients treated with nintedanib had comparable treatment emergent adverse event (TEAE) profiles in clinical practice to those reported in clinical trials. The TEAE profile of pirfenidone was higher than clinical trial data would suggest, although comparable to real-world datasets. Further work is required to explore the possible reasons underpinning this finding, including whether this is related to population co-morbidities or center threshold. No new safety concerns were identified.

Specialist palliative care, psychology, interstitial lung disease (ILD) multidisciplinary team meeting: a novel model to address palliative care needs.

INTRODUCTION: Patients with progressive idiopathic fibrotic interstitial lung disease (ILD), such as those with idiopathic pulmonary fibrosis (IPF), can have an aggressive disease course, with a median survival of only 3-5 years from diagnosis. The palliative care needs of these patients are often unmet. There are calls for new models of care, whereby the patient's usual respiratory clinician remains central to the integration of palliative care principles and practices into their patient's management, but the optimal model of service delivery has yet to be determined. METHODS: We developed a novel, collaborative, multidisciplinary team (MDT) meeting between our palliative care, psychology and ILD teams with the principal aim of integrating specialist care to ensure the needs of persons with ILD, and their caregivers were identified and met by referral to the appropriate service. The objective of this study was to assess the effectiveness of this novel MDT meeting on the assessment of a patient's palliative care needs. RESULTS: Significant increases in advance care planning discussions were observed, in conjunction with increased referrals to community courses and teams, following introduction of this novel MDT. CONCLUSIONS: Our results suggest that our collaborative MDT is an effective platform to address patients' unmet palliative care needs. Further work is required to explore the effect of our model on achieving the preferred place of death and reductions in unplanned hospital admissions.

A comparison of published multidimensional indices to predict outcome in idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) has an unpredictable course and prognostic factors are incompletely understood. We aimed to identify prognostic factors, including multidimensional indices from a significant IPF cohort at the Bristol Interstitial Lung Disease Centre in the UK. Patients diagnosed with IPF between 2007 and 2014 were identified. Longitudinal pulmonary physiology and exercise testing results were collated, with all-cause mortality used as the primary outcome. Factors influencing overall, 12- and 24-month survival were identified using Cox proportional hazards modelling and receiver operating characteristic curve analysis. We found in this real-world cohort of 167 patients, diffusing capacity for carbon monoxide (DLCO) and initiation of long-term oxygen were independent markers of poor prognosis. Exercise testing results predicted 12-month mortality as well as DLCO, but did not perform as well for overall survival. The Composite Physiological Index was the best performing multidimensional index, but did not outperform DLCO. Our data confirmed that patients who experienced a fall in forced vital capacity (FVC) >10% had significantly worse survival after that point (p=0.024). Our data from longitudinal follow-up in IPF show that DLCO is the best individual prognostic marker, outperforming FVC. Exercise testing is important in predicting early poor outcome. Regular and complete review should be conducted to ensure appropriate care is delivered in a timely fashion.

Pulmonary Langerhans cell histiocytosis (PLCH): a new UK register.

Pulmonary Langerhans cell histiocytosis (PLCH) is a rare interstitial lung disease of unknown aetiology. We aimed to characterise a UK-wide cohort of patients with PLCH and compare diagnostic and management methods in specialist and non-specialist centres. 106 cases (53 hospitals) identified. Complete data received in 67 cases (53.7% female, age 37.1±14.4 years). 96% current or ex-smokers. Treatment; smoking cessation (79%), corticosteroids (30.6%), cytotoxic therapy (26.9%) and lung transplant (6%). Patients at specialist centres received cytotoxic drugs more often (p=0.0001) and survival appeared higher. This dataset indicates a more even gender distribution than previously documented. It suggests variation in clinical management and outcomes achieved dependent on clinical experience.

Current and novel drug therapies for idiopathic pulmonary fibrosis.

Over the past decade, there has been a cohesive effort from patients, physicians, clinical and basic scientists, and the pharmaceutical industry to find definitive treatments for idiopathic pulmonary fibrosis (IPF). As understanding of disease behavior and pathogenesis has improved, the aims of those treating IPF have shifted from reversing the disease to slowing or preventing progression of this chronic fibrotic illness. It is to be hoped that by slowing disease progression, survival will be improved from the current dismal median of 3.5 years following diagnosis. In Europe and Asia, a milestone has recently been reached with the licensing of the first IPF-specific drug, pirfenidone. This review assesses the current treatment modalities available for IPF, including pirfenidone. It also turns an eye to the future and discusses the growing number of promising compounds currently in development that it is hoped, in time, will make their way into the clinic as treatments for IPF.

International collaboration: a retrospective study examining the survival of Irish citizens following lung transplantation in both the UK and Ireland.

OBJECTIVE: Prior to 2005, Irish citizens had exclusively availed of lung transplantation services in the UK. Since 2005, lung transplantation has been available to these patients in both the UK and Ireland. We aimed to evaluate the outcomes of Irish patients undergoing lung transplantation in both the UK and Ireland. DESIGN: We retrospectively examined the outcome of Irish patients transplanted in the UK and Ireland. Lung allocation score (LAS) was used as a marker of disease severity. RESULTS: A total of 134 patients have undergone transplantation. 102 patients underwent transplantation in the UK and 32 patients in Ireland. In total, 52% were patients with cystic fibrosis, 19% had emphysema and 15% had idiopathic pulmonary fibrosis. In Ireland, 44% of the patients suffered from idiopathic pulmonary fibrosis, 31% had emphysema and 16% had cystic fibrosis. A total of 96 double sequential transplants and 38 single transplants have been performed. LAS of all patients undergoing lung transplantation was 37.8 (±1.02). The mean LAS for patients undergoing lung transplantation in Ireland was 44.7 (±3.1), and 35 (±0.4) for patients undergoing lung transplantation in the UK (p<0.05). The 5-year survival of all Irish citizens who had undergone lung transplantation was 73%. The 5-year survival of Irish patients transplanted in the UK was 69% and in Ireland was 91% and 73% at 5.01 years. CONCLUSIONS: International collaboration can be achieved, as evidenced by the favourable outcomes seen in Irish citizens who undergo lung transplantation in both the UK and Ireland. Irish citizens undergoing lung transplantation in Ireland have a higher LAS score. Despite excellent outcomes, an intention-to-treat analysis of the treatment utility (transplant) indicates the limited effectiveness of lung transplantation in Ireland and emphasises the need for increased rates of lung transplantation.

Acute exacerbations and pulmonary hypertension in advanced idiopathic pulmonary fibrosis.

The aim of this study was to evaluate the risk factors for and outcomes of acute exacerbations in patients with advanced idiopathic pulmonary fibrosis (IPF), and to examine the relationship between disease severity and neovascularisation in explanted IPF lung tissue. 55 IPF patients assessed for lung transplantation were divided into acute (n=27) and non-acute exacerbation (n=28) groups. Haemodynamic data was collected at baseline, at the time of acute exacerbation and at lung transplantation. Histological analysis and CD31 immunostaining to quantify microvessel density (MVD) was performed on the explanted lung tissue of 13 transplanted patients. Acute exacerbations were associated with increased mortality (p=0.0015). Pulmonary hypertension (PH) at baseline and acute exacerbations were associated with poor survival (p<0.01). PH at baseline was associated with a significant risk of acute exacerbations (HR 2.217, p=0.041). Neovascularisation (MVD) was significantly increased in areas of cellular fibrosis and significantly decreased in areas of honeycombing. There was a significant inverse correlation between mean pulmonary artery pressure and MVD in areas of honeycombing. Acute exacerbations were associated with significantly increased mortality in patients with advanced IPF. PH was associated with the subsequent development of an acute exacerbation and with poor survival. Neovascularisation was significantly decreased in areas of honeycombing, and was significantly inversely correlated with mean pulmonary arterial pressure in areas of honeycombing.

Postnatal development and regulation of beta-hexosaminidase in epithelial cells of the rat epididymis.

beta-Hexosaminidase (Hex) catalyzes the hydrolysis of terminal sugar residues from a number of substrates such as GM2 gangliosides, glycoproteins, glycolipids, and glycosaminoglycans. As an enzyme present in lysosomes of epithelial cells of the adult rat epididymis, it serves to degrade substances endocytosed from the epididymal lumen. In this way, it modifies and creates a luminal environment where sperm can undergo their maturational modifications. In this study, the postnatal developmental pattern of expression of Hex was examined in animals from days 7-56. In addition, the role of testicular factors on Hex expression in the different cell types and regions of the epididymis of adult rats was examined in orchidectomized and efferent duct-ligated rats. Both parameters were examined on Bouin-fixed epididymides in conjunction with light microscope immunocytochemistry. At postnatal day 7, the epithelium of the entire epididymis was unreactive for anti-Hex antibody. By day 21, narrow and clear cells of their respective regions became reactive, whereas basal cells became reactive only by day 29. Principal cells displayed only an occasional reactive lysosome at day 21, several by day 29, and numerous reactive lysosomes by day 39, comparable to the region-specific distribution noted for 90-day-old animals, and at an age when high androgen levels are attained. Thus, postnatal onset of Hex expression varies according to the different cell types of the epididymis, suggesting different regulatory factors. This finding was confirmed from studies employing adult orchidectomized and efferent duct-ligated adult rats. Indeed, in all experimental animals, Hex immunostaining in narrow, clear, and basal cells was intense and comparable to control animals. In contrast, there was a notable absence of lysosomal staining in principal cells at all time points after orchidectomy, which was restored, however, following testosterone replacement. No effect on Hex expression was observed in efferent duct-ligated animals. Taken together, the data suggest that Hex expression in lysosomes of principal cells is regulated by testosterone or one of its metabolites. However, the expression of Hex being independent of testicular factors in narrow, clear, and basal cells of adult animals, but occurring at different time points during postnatal development, suggests that different regulatory factors are responsible for onset of Hex expression in these cell types during development.