Highly differentiated cytotoxic T cells in inclusion body myositis.

Inclusion body myositis is a late onset treatment-refractory autoimmune disease of skeletal muscle associated with a blood autoantibody (anti-cN1A), an HLA autoimmune haplotype, and muscle pathology characterized by cytotoxic CD8+ T cell destruction of myofibres. Here, we report on translational studies of inclusion body myositis patient muscle compared with a diverse set of other muscle disease samples. Using available microarray data on 411 muscle samples from patients with inclusion body myositis (n = 40), other muscle diseases (n = 265), and without neuromuscular disease (normal, n = 106), we identified a signature of T-cell cytotoxicity in inclusion body myositis muscle coupled with a signature of highly differentiated CD8 T-cell effector memory and terminally differentiated effector cells. Further, we examined killer cell lectin-like receptor G1 (KLRG1) as a marker of this population of cells, demonstrated the correlation of KLRG1 gene expression with lymphocyte cytotoxicity across 28 870 human tissue samples, and identified the presence of KLRG1 on pathogenic inclusion body myositis muscle invading T cells and an increase in KLRG1 expressing T cells in inclusion body myositis blood. We examined inclusion body myositis muscle T-cell proliferation by Ki67 immunohistochemistry demonstrating that diseased muscle-invading T cells are minimally or non-proliferative, in accordance with known properties of highly differentiated or terminally differentiated T cells. We found low expression of KLRG1 on infection-protective human lymphoid tissue central memory T cells and autoimmune-protective human blood regulatory T cells. Targeting highly differentiated cytotoxic T cells could be a favourable approach to treatment of inclusion body myositis.

Mutations in prion-like domains in hnRNPA2B1 and hnRNPA1 cause multisystem proteinopathy and ALS.

Algorithms designed to identify canonical yeast prions predict that around 250 human proteins, including several RNA-binding proteins associated with neurodegenerative disease, harbour a distinctive prion-like domain (PrLD) enriched in uncharged polar amino acids and glycine. PrLDs in RNA-binding proteins are essential for the assembly of ribonucleoprotein granules. However, the interplay between human PrLD function and disease is not understood. Here we define pathogenic mutations in PrLDs of heterogeneous nuclear ribonucleoproteins (hnRNPs) A2B1 and A1 in families with inherited degeneration affecting muscle, brain, motor neuron and bone, and in one case of familial amyotrophic lateral sclerosis. Wild-type hnRNPA2 (the most abundant isoform of hnRNPA2B1) and hnRNPA1 show an intrinsic tendency to assemble into self-seeding fibrils, which is exacerbated by the disease mutations. Indeed, the pathogenic mutations strengthen a 'steric zipper' motif in the PrLD, which accelerates the formation of self-seeding fibrils that cross-seed polymerization of wild-type hnRNP. Notably, the disease mutations promote excess incorporation of hnRNPA2 and hnRNPA1 into stress granules and drive the formation of cytoplasmic inclusions in animal models that recapitulate the human pathology. Thus, dysregulated polymerization caused by a potent mutant steric zipper motif in a PrLD can initiate degenerative disease. Related proteins with PrLDs should therefore be considered candidates for initiating and perhaps propagating proteinopathies of muscle, brain, motor neuron and bone.

Association of inclusion body myositis with T cell large granular lymphocytic leukaemia.

SEE HOHLFELD AND SCHULZE-KOOPS DOI101093/BRAIN/AWW053 FOR A SCIENTIFIC COMMENTARY ON THIS ARTICLE: Inclusion body myositis and T cell large granular lymphocytic leukaemia are rare diseases involving pathogenic cytotoxic CD8+ T cells. After encountering four patients with both disorders, we prospectively screened 38 patients with inclusion body myositis for the presence of expanded large granular lymphocyte populations by standard clinical laboratory methods (flow cytometry, examination of blood smears, and T cell receptor gene rearrangements), and performed muscle immunohistochemistry for CD8, CD57, and TIA1. Most (22/38; 58%) patients with inclusion body myositis had aberrant populations of large granular lymphocytes in their blood meeting standard diagnostic criteria for T cell large granular lymphocytic leukaemia. These T cell populations were clonal in 20/20 patients and stably present on follow-up testing in 15 patients a median of 350 days later. T cell aberrant loss of CD5 or gain of expression of CD16 and CD94 were common (19/42, 45%). In comparison, 2/15 (14%) age-matched patients with dermatomyositis, polymyositis, or necrotizing myopathy, and 0/20 (0%) age-matched healthy subjects had large granular lymphocyte expansions, with none of these patients having T cell aberrant expression of CD5, CD16 or CD94. Reduced blood CD4/CD8 ratio, increased blood CD8 count, and lymphocytosis were additional biomarkers highly correlated with flow cytometry-measured large granular lymphocyte expansions. Cross-sectional data suggested more aggressive disease in patients with such expansions than without. Muscle immunohistochemistry demonstrated invasion of large granular lymphocytes into muscle in 15/15 inclusion body myositis patients but in only 1/28 patients with dermatomyositis or polymyositis. The extent of CD8+ and CD57+ cells in inclusion body myositis muscle correlated with the size of blood large granular lymphocyte populations. Myofibre-invading cells expressed CD57, a marker of persistent T cell exposure to antigen and T cell aggressiveness. In many patients with inclusion body myositis, the autoimmune T cell expansion has evolved into a neoplastic-like or overtly neoplastic disorder, perhaps contributing to its relative refractoriness to immune-directed therapies previously reported.

Cytosolic 5'-nucleotidase 1A autoimmunity in sporadic inclusion body myositis.

OBJECTIVE: We previously identified a circulating autoantibody against a 43 kDa muscle autoantigen in sporadic inclusion body myositis (IBM) and demonstrated the feasibility of an IBM diagnostic blood test. Here, we sought to identify the molecular target of this IBM autoantibody, understand the relationship between IBM autoimmunity and muscle degeneration, and develop an IBM blood test with high diagnostic accuracy. METHODS: IBM blood samples were screened using mass spectrometry and a synthetic human peptidome. Plasma and serum samples (N=200 patients) underwent immunoblotting assays, and results were correlated to clinical features. Muscle biopsy samples (n=30) were examined by immunohistochemistry and immunoblotting. Exome or whole genome sequencing was performed on DNA from 19 patients. RESULTS: Both mass spectrometry and screening of a 413,611 human peptide library spanning the entire human proteome identified cytosolic 5'-nucleotidase 1A (cN1A; NT5C1A) as the likely 43 kDa IBM autoantigen, which was then confirmed in dot blot and Western blot assays using recombinant cN1A protein. Moderate reactivity of anti-cN1A autoantibodies was 70% sensitive and 92% specific, and high reactivity was 34% sensitive and 98% specific for the diagnosis of IBM. One to 3 major cN1A immunodominant epitopes were identified. cN1A reactivity by immunohistochemistry accumulated in perinuclear regions and rimmed vacuoles in IBM muscle, localizing to areas of myonuclear degeneration. INTERPRETATION: Autoantibodies against cN1A are common in and highly specific to IBM among muscle diseases, and may provide a link between IBM's dual processes of autoimmunity and myodegeneration. Blood diagnostic testing is feasible and should improve early and reliable diagnosis of IBM.

Interferon-stimulated gene 15 (ISG15) conjugates proteins in dermatomyositis muscle with perifascicular atrophy.

OBJECTIVE: We investigated interferon-stimulated gene 15 (ISG15), a poorly understood ubiquitin-like modifier, and its enzymatic pathway in dermatomyositis (DM), an autoimmune disease primarily involving muscle and skin. METHODS: We generated microarray data measuring transcript abundance for approximately 18,000 genes in each of 113 human muscle biopsy specimens, and studied biopsy specimens and cultured skeletal muscle using immunohistochemistry, immunoblotting proteomics, real-time quantitative polymerase chain reaction, and laser-capture microdissection. RESULTS: Transcripts encoding ISG15-conjugation pathway proteins were markedly upregulated in DM with perifascicular atrophy (DM-PFA) muscle (ISG15 339-fold, HERC5 62-fold, and USP18 68-fold) compared with 99 non-DM samples. Combined analysis with publicly available microarray datasets showed that >50-fold ISG15 transcript elevation had 100% sensitivity and specificity for 28 biopsies from adult DM-PFA and juvenile DM patients compared with 199 muscle samples from other muscle diseases. Free ISG15 and ISG15-conjugated proteins were only found on immunoblots from DM-PFA muscle. Cultured human skeletal muscle exposed to type 1 interferons produced similar transcripts and ISG15 protein and conjugates. Laser-capture microdissection followed by proteomic analysis showed deficiency of titin in DM perifascicular atrophic myofibers. INTERPRETATION: A large-scale microarray study of muscle samples demonstrated that among a diverse group of muscle diseases DM was uniquely associated with upregulation of the ISG15 conjugation pathway. Exposure of human skeletal muscle cell culture to type 1 interferons produced a molecular picture highly similar to that seen in human DM muscle. Perifascicular atrophic myofibers in DM were deficient in a number of skeletal muscle proteins including titin.

The iron exporter ferroportin/Slc40a1 is essential for iron homeostasis.

Ferroportin (SLC40A1) is an iron transporter postulated to play roles in intestinal iron absorption and cellular iron release. Hepcidin, a regulatory peptide, binds to ferroportin and causes it to be internalized and degraded. If ferroportin is the major cellular iron exporter, ineffective hepcidin function could explain manifestations of human hemochromatosis disorders. To investigate this, we inactivated the murine ferroportin (Fpn) gene globally and selectively. Embryonic lethality of Fpn(null/null) animals indicated that ferroportin is essential early in development. Rescue of embryonic lethality through selective inactivation of ferroportin in the embryo proper suggested that ferroportin has an important function in the extraembryonic visceral endoderm. Ferroportin-deficient animals accumulated iron in enterocytes, macrophages, and hepatocytes, consistent with a key role for ferroportin in those cell types. Intestine-specific inactivation of ferroportin confirmed that it is critical for intestinal iron absorption. These observations define the major sites of ferroportin activity and give insight into hemochromatosis.

Permissive environment for B-cell maturation in myositis muscle in the absence of B-cell follicles.

Myositis muscle contains antigen-matured B-cells and plasma cells. Myositis muscle biopsy specimens were examined for nodular collections of T-cells, B-cells, myeloid dendritic cells, plasma cells, and follicular dendritic cells. Immunoglobulin and B-cell-activating factor (BAFF) transcripts were quantitated. Laser-capture microdissection was used to isolate single plasma cells, and their immunoglobulin transcripts were sequenced. Dense inflammatory infiltrates contained histological elements of ectopic lymphoid tissue but not B-cell follicles. Immunoglobulin transcript sequence analysis demonstrated spatially distributed, clonally related B-cells and plasma cells, suggesting local maturation of B-cells into plasma cells in myositis muscle. Regions of dense cellular infiltrates in myositis muscle are sometimes areas of B-cell maturation into antibody-producing plasma cells. An atypical lymphoid histology, lacking concentrated collections of germinal-center-like B-cell follicles, is capable of antigen-stimulated clonal maturation of antibody-producing plasma cells.

A mouse model of juvenile hemochromatosis.

Hereditary hemochromatosis is an iron-overload disorder resulting from mutations in proteins presumed to be involved in the maintenance of iron homeostasis. Mutations in hemojuvelin (HJV) cause severe, early-onset juvenile hemochromatosis. The normal function of HJV is unknown. Juvenile hemochromatosis patients have decreased urinary levels of hepcidin, a peptide hormone that binds to the cellular iron exporter ferroportin, causing its internalization and degradation. We have disrupted the murine Hjv gene and shown that Hjv-/- mice have markedly increased iron deposition in liver, pancreas, and heart but decreased iron levels in tissue macrophages. Hepcidin mRNA expression was decreased in Hjv-/- mice. Accordingly, ferroportin expression detected by immunohistochemistry was markedly increased in both intestinal epithelial cells and macrophages. We propose that excess, unregulated ferroportin activity in these cell types leads to the increased intestinal iron absorption and plasma iron levels characteristic of the juvenile hemochromatosis phenotype.

Immunohistochemical analysis of langerin in langerhans cell histiocytosis and pulmonary inflammatory and infectious diseases.

Pulmonary Langerhans cell histiocytosis (LCH) is an idiopathic condition affecting predominantly adult smokers. Histologically, LCH is characterized by a nodular, interstitial proliferation of Langerhans cells around the distal airways with associated eosinophils, lymphocytes, and macrophages. Associated findings, such as fibrosis, emphysematous change, and bronchiolitis can be reminiscent of other interstitial lung diseases. The markers CD1a and S100 have traditionally been used to distinguish LCH from other processes. Little is known about expression of the Langerhans cell-specific lectin, langerin, in pulmonary diseases. We examined the expression patterns of S100, CD1a, and langerin in LCH and other interstitial, inflammatory, and infectious processes in cases retrieved from the files at Brigham and Women's Hospital Department of Pathology. Immunoreactivity was scored according to the number of cells staining per high power field (400x) in areas of highest density, averaged over 4 fields. Cases diagnosed as LCH based on histomorphology and positive CD1a and S100 staining demonstrated strong langerin positivity in lesional tissue. All cases of LCH contained greater than 30 langerin and CD1a positive cells per high power field (HPF), with a mean of >100 cells per HPF, in lesional tissue. Of the other interstitial processes examined, only usual interstitial pneumonia demonstrated increased number of Langerhans cells within epithelium and interstitium (mean 14 cells per HPF) as compared with normal lung (mean 6 cells per HPF). Langerin and CD1a serve as specific diagnostic markers in distinguishing LCH from other interstitial and inflammatory processes.

CD4+/CD56+ hematodermic neoplasm ("blastic natural killer cell lymphoma"): neoplastic cells express the immature dendritic cell marker BDCA-2 and produce interferon.

CD4+/CD56+ hematodermic neoplasm ("blastic natural killer [NK]-cell lymphoma") is a rare highly aggressive neoplasm associated with cutaneous manifestations followed by dissemination to blood, bone marrow, and other tissues. Neoplastic cells exhibit a lineage-negative CD4+/CD56+/CD43+/HLA-DR+ immunophenotype, initially suggesting an NK-cell derivation. The recent discovery of CD123 antigen expression by tumor cells has provided evidence for a relationship to immature dendritic cells (DCs), a group of myeloid and lymphoid early-committed progenitors capable of differentiating into antigen-presenting DCs. Based on flow cytometric analysis, myeloid DCs represent the majority of human peripheral blood DCs and are positive for blood dendritic cell antigen (BDCA)-1 (or CD1c), CD13, CD11c(high), CD33, and CD123(low). Plasmacytoid DCs are BDCA-2+/ CD123(high)+/CD13-/CD33- and produce interferon (IFN)-alpha when triggered by antigens. IFN-alpha production may be detected in tissue sections using antibodies for myxovirus A (MxA) protein, a surrogate marker. This report describes the clinical, histologic, immunophenotypic, cytogenetic, and molecular genetic findings for 3 cases of CD4+/CD56+ hematodermic neoplasms. In all cases, neoplastic cells were reactive for CD123, BDCA-2, and MxA protein, providing strong evidence for an immature plasmacytoid DC derivation for this rare neoplasm.

α-Hemoglobin-stabilizing Protein: An Effective Marker for Erythroid Precursors in Bone Marrow Biopsy Specimens.

Accurate analysis of the erythroid lineage is essential in evaluating bone marrow biopsies and can be particularly challenging in settings of dyserythropoiesis. α-Hemoglobin-stabilizing protein (AHSP) is an erythroid-specific chaperone protein and represents a potential specific marker for erythroid elements. This study defines the immunohistochemical profile of AHSP, as compared with an established erythroid marker CD71, in 101 bone marrow biopsies including normal marrows and cases of acute pure erythroid leukemia, acute erythroid/myeloid leukemia, other types of acute myeloid leukemia, myelodysplastic syndrome, chronic myelogenous leukemia, other types of myeloproliferative neoplasm, chronic myelomonocytic leukemia, acute lymphoblastic leukemia, plasma cell neoplasm, and metastatic carcinoma. In acute pure erythroid leukemia, blasts in 7 of 11 cases showed similar reactivity for CD71 and AHSP, whereas less extensive reactivity was observed for AHSP as compared with CD71 in the remaining 4 cases. In normal marrows and other various disorders, reactivity for AHSP was similar to CD71 and was restricted to the erythroid lineage. Mature erythrocytes were negative for AHSP as were myeloblasts, lymphoblasts, nonerythroid hematopoietic marrow elements, plasma cells, and carcinoma cells. AHSP is an effective marker for detection of normal or abnormal erythroid precursors in bone marrow biopsies and is a useful addition to an immunohistochemical panel for assessment of neoplastic cells of possible erythroid derivation.

Clusterin, a marker for anaplastic large cell lymphoma immunohistochemical profile in hematopoietic and nonhematopoietic malignant neoplasms.

We evaluated the immunohistochemical staining profile of clusterin in paraffin sections of 143 neoplasms (non-Hodgkin lymphoma, 83, including 41 anaplastic large cell lymphomas [ALCLs]; Hodgkin lymphoma, 17; primary and metastatic carcinoma, 30; and other neoplasms, 13). In 40 of 41 ALCLs (34 systemic, 7 cutaneous), neoplastic cells revealed clusterin reactivity characterized by a Golgi staining pattern. The proportion of reactive cells varied with more than 25% positive cells in the majority of cases. In 7 non-Hodgkin lymphomas of other types, fine cytoplasmic (3 cases) or strong membranous reactivity (4 cases) was observed for clusterin. In Hodgkin lymphoma, rare Reed-Sternberg cells exhibited focal cytoplasmic or membranous clusterin positivity. In the nonhematopoietic neoplasms, a Golgi staining pattern was apparent in only 2 cases, 1 lobular carcinoma of the breast and 1 poorly differentiated colonic carcinoma; however, cytoplasmic reactivity was noted in 12 of 30 carcinomas and 1 of 5 neuroendocrine neoplasms. A Golgi pattern of reactivity for clusterin seems highly characteristic of ALCL among hematopoietic neoplasms, but also might be observed in rare nonhematopoietic tumors, necessitating the use of a broad immunohistochemical panel for evaluation of poorly differentiated neoplasms of indeterminate derivation.

CD138 (syndecan-1), a plasma cell marker immunohistochemical profile in hematopoietic and nonhematopoietic neoplasms.

We evaluated the immunohistochemical profile and specificity of CD138 reactivity in 238 specimens from hematopoietic and nonhematopoietic neoplasms. In 91 bone marrow biopsies, CD138 reactivity was observed for nonneoplastic plasma cells, neoplastic plasma cells in multiple myeloma cases (43/43), and the plasmacytic component in lymphoplasmacytic lymphoma cases (4/4). Stromal reactivity was noted in 7 multiple myeloma cases. Of 9 bone marrow specimens involved by metastatic carcinoma, tumor cells were CD138+ in 5 cases; stromal reactivity was noted in 7 cases. Studies of 76 nodal and extranodal lymphomas (B-cell, 49; T-cell, 8; Hodgkin lymphoma, 19), 1 Langerhans cell histiocytosis, and 14 nonneoplastic lymph nodes revealed CD138 reactivity only for nonneoplastic plasma cells, the neoplastic cells of 2 large B-cell lymphomas (immunoblastic type, plasmacytoid features), and the clonal plasmacytic component of 3 of 3 extranodal and 1 nodal marginal zone lymphoma. Evaluation of 56 epithelial and nonepithelial tumors revealed CD138 positivity for neoplastic cells of carcinomas of various types (30/33), frequently with associated stromal reactivity, and for neoplasms of mesenchymal, melanocytic, and other tumor types (12/23). Within the hematopoietic system, CD138 is an excellent marker of plasmacytic differentiation. Based on its broad staining profile, CD138 reactivity for neoplastic cells is not a definitive marker for plasmacytic derivation, unless a hematolymphoid origin has been established.

Langerhans cell histiocytosis immunohistochemical expression of fascin, a dendritic cell marker.

Langerhans cell histiocytosis (LCH) is a clonal disorder believed to be derivedfrom cells of the dendritic system. Fascin, a 55-kd actin-bundling protein, represents a highly selective marker for dendritic cells of lymphoid tissues and peripheral blood and is involved in the formation of dendritic processes in maturing epidermal Langerhans cells. Since lesional cells of LCH may represent Langerhans cells arrested at an early stage of activation, immunohistochemical expression offascin in epidermal Langerhans cells and in the lesional cells of 34 cases of LCH was evaluated in paraffin sections using an immunoalkaline phosphatase technique. Though epidermal Langerhans cells were nonreactive for fascin, lesional cells in all LCH cases exhibited immunoreactivityforfascin, CD1a, and S-100 protein. Variation in staining intensity was observed in some cases, possibly reflecting differences in cell maturation or activation. Involved tissues included bone, soft tissue, lymph node, thyroid, orbit, and extradural cranial tissue. Immunoreactivity of lesional cells of LCH for fascin supports their derivation from cells of the dendritic system and represents another alteration in the phenotype of Langerhans cells that is associated with maturation, migration, culture, or clonal expansion.

Comparison of thyroid transcription factor-1 and hepatocyte antigen immunohistochemical analysis in the differential diagnosis of hepatocellular carcinoma, metastatic adenocarcinoma, renal cell carcinoma, and adrenal cortical carcinoma.

We compared the effectiveness of thyroid transcription factor-1 (TTF-1, cytoplasmic reactivity) and hepatocyte antigen (HPA) as markers for characterization of hepatocellular carcinoma (HCC) and as discriminators to distinguish HCC from its histologic and cytologic mimics. Formalin-fixed, paraffin-embedded sections of 258 specimens, including 76 HCCs, 85 metastatic adenocarcinomas, 75 renal cell carcinomas (RCCs), and 22 adrenal cortical carcinomas (ACCs), were evaluated. Specimens included tissue sections and cytologic material (cell blocks). Following heat-induced epitope retrieval, immunohistochemical studies were performed using an indirect immunoperoxidase technique. Cytoplasmic reactivity for TTF-1 was noted for 54 (71%) of 76 HCCs, 3 (4%) of 85 adenocarcinomas, none of 72 RCCs, and none of 22 ACCs. Cytoplasmic reactivity for HPA was observedfor 50 (66%) of 76 HCCs, 1 (1%) of 83 adenocarcinomas, none of 74 RCCs, and none of 21 ACCs. Cytoplasmic reactivity for TTF-1 and HPA is highly specific for HCC, although a minority of HCCs, particularly poorly differentiated tumors, may be nonreactive. Thus, these markers are usefulfor the characterization of HCC in tissue sections and cell blocks and are highly effective for distinguishing these tumors from other neoplasms included in the differential diagnosis.

WT1, estrogen receptor, and progesterone receptor as markers for breast or ovarian primary sites in metastatic adenocarcinoma to body fluids.

In tissue sections, detection of the Wilms tumor susceptibility gene 1 (WTI) protein, the hormonal receptors for estrogen (ER) and progesterone (PR), and gross cystic disease fluid protein (GCDFP) are useful for diagnosing ovarian and breast adenocarcinomas. We evaluated these markers for cytology cell-block preparations from 96 effusion specimens (metastases from 29 breast, 22 ovarian, and 45 adenocarcinomas from other sites). WTI protein was reactive in 19 cases inetastatic from ovary (86%), 2 from breast (7%), and none from other sites (specificity; 97%). Of the metastatic breast carcinomas, 21(72%) were reactive for ER, 15(52%) for PR, and 13 (45%) for both (combined specificity, 84%). GCDEP was reactive in only 4 breast cancer cases (14%). Ovarian tumors also were frequently positive for ER (19 [86%]), PR (II [SO%]), or both (10 [45%]). WTI protein is an effective marker for ovarian adenocarcinoma, especially in ascites. The detection of ER and PR in metastatic adenocarcinoma from pleural or pericardial efflusions can distinguish breast from lung primary sites. Reactivity for ER and PR did not distinguish between breast and ovarian metastases; however; studies for WTI protein and GCDFP may aid in making this distinction.

Enhanced detection of atypical hyperplasia in endometrial polyps by PTEN expression.

Endometrial hyperplasia is difficult to recognize within endometrial polyps because of the background of randomly distributed irregular glands. The loss of expression of the PTEN oncogene is characteristic of endometrial cancers and clinically significant hyperplasia. Using immunohistochemical staining for the PTEN protein, we studied 12 endometrial polyps that were noted to contain foci of complex hyperplasia or glandular crowding. Loss of PTEN staining was found in 3 cases, suggesting a precancerous lesion. Moreover, 2 of these cases were originally classified as complex hyperplasia without atypia and 1 as merely glandular crowding. Thus, in selected cases, the loss of PTEN expression in an area of glandular crowding can highlight biologically significant lesions and afford a more definitive diagnosis.

Abnormal distribution of heterogeneous nuclear ribonucleoproteins in sporadic inclusion body myositis.

Previous histopathologic studies of sporadic inclusion body myositis (sIBM) identified sarcoplasmic aggregation and myonuclear depletion of the predominantly nuclear heterogeneous nuclear ribonucleoprotein (hnRNP) TDP-43 in sIBM myofibers. Here, we examined sIBM muscle for abnormalities in two other hnRNPs hnRNPA1 and hnRNPA2B1, mutations in which cause multisystem proteinopathy associated with rimmed-vacuolar myopathies. Muscle biopsy specimens from 13 patients with sIBM and 13 patients without sIBM (dermatomyositis N=3, polymyositis N=3, muscular dystrophy N=3, motor neuron disease N=2, non-neuromuscular disease N=2) underwent immunohistochemistry for hnRNPA1, hnRNPA2B1, and TDP-43. Muscle transcriptional microarray data from 27 patients with sIBM and 12 patients without neuromuscular disease was analyzed. Depletion of hnRNPA1 and hnRNPA2B1 was present in 15% and 7% of sIBM myonuclei, respectively, compared with 1% and 0% of myonuclei in non-sIBM muscle. Sarcoplasmic aggregates of hnRNPA1 and hnRNPA2B1 distinct from TDP-43 aggregates were also found in sIBM. hnRNPA1 and hnRNPA2B1, as well as other hnRNPs, gene expression was unaltered in sIBM compared to normal muscle. Along with TDP-43, other hnRNPs, including hnRNPA1 and hnRNPA2B1, are depleted from sIBM myonuclei at the protein but not transcript level. The depletion of multiple hnRNPs from sIBM myonuclei together with their sarcoplasmic aggregation suggests that one aspect of sIBM pathophysiology may involve abnormal RNA metabolism that includes hyperassembly of ribonucleoprotein granules mediated by prion-like domains in hnRNPs, evolving into pathological aggregates.

Profile of CD103 expression in T-cell neoplasms: immunoreactivity is not restricted to enteropathy-associated T-cell lymphoma.

Intestinal intraepithelial T lymphocytes express the α E subunit of integrin αEß7, which is detected by antibodies to CD103. Accordingly, within T-cell neoplasms, CD103 reactivity has most frequently been reported in enteropathy-associated T-cell lymphomas, which are postulated to arise from intestinal intraepithelial T lymphocytes. However, prior studies of CD103 expression in T-cell neoplasms have been limited by the requirement for fresh or frozen tissue, given the historic lack of an antibody to CD103 for use in paraffin-embedded sections. Thus, a thorough assessment of CD103 expression in a broad spectrum of T-cell neoplasms as categorized by the current classification system has not yet been performed. This study uses a newly described antibody to define the profile of CD103 immunoreactivity in paraffin sections of a wide variety of T-cell neoplasms (184 cases). Overall, 22 T-cell neoplasms (12%) were CD103 positive, including 7 of 15 gastrointestinal lymphomas (3.8% of total cases; 46% of gastrointestinal cases). In intestinal cases, CD103 positivity did not correlate with morphology, presence or absence of enteropathy, or immunohistochemical profile. A history of celiac disease was not documented in any case. Frequent but inconsistent reactivity was also noted for adult T-cell leukemia/lymphoma with 4 of 10 cases (40%) positive. In the remaining T-cell neoplasms representing most entities within the current World Health Organization classification, CD103 reactivity was sporadically observed in 11 of 159 cases (6.9%). CD103 positivity is an unusual feature in T-cell neoplasms and tends to occur in gastrointestinal lymphomas and adult T-cell leukemia/lymphoma but is not a consistent characteristic of these neoplasms.

Immunohistochemical detection of hairy cell leukemia in paraffin sections using a highly effective CD103 rabbit monoclonal antibody.

Detection of the integrin subunit CD103 is a useful diagnostic tool in the diagnosis of hairy cell leukemia (HCL). Currently, flow cytometric analysis (FC) and frozen section immunohistochemistry (IHC) represent the only available methods of detection. This study is the first to describe the successful use of a CD103 antibody to identify HCL and HCL-variant in paraffin sections of formalin- or Bouin solution- fixed specimens (n = 68) using an immunoperoxidase technique. In other B-cell lymphoproliferative disorders that morphologically may resemble HCL, including chronic lymphocytic leukemia/small lymphocytic lymphoma (n = 32), mantle cell lymphoma (n = 23), lymphoplasmacytic lymphoma (n = 27), follicular lymphoma (n = 7), and marginal zone lymphoma (n = 13), lymphoid cells are nonreactive for CD103. In HCL, the CD103 staining pattern is predominantly membranous with delineation of delicate cytoplasmic projections. This CD103 antibody is an extremely valuable addition to the IHC panel for the diagnosis of HCL, especially in cases lacking FC analysis.