The Pathophysiology of Bullous Pemphigoid

Bullous pemphigoid (BP) is a blistering skin disease characterized by an autoimmune response to 2 hemidesmosomal proteins within the dermal–epidermal junction, designated BP180 and BP230. While BP230 localizes intracellularly and associates with the hemidesmosomal plaque, BP180 is a transmembrane glycoprotein with an extracellular domain. Most BP patients have autoantibodies binding to an immunodominant region of BP180, the noncollagenous 16A domain (NC16A), which is located extracellularly close to the transmembrane domain of the protein. Autoreactive T and B cell responses to BP180 have been found in patients with BP. Passive transfer of antibodies to the murine BP180 ectodomain triggers a blistering skin disease in mice that closely mimics human BP. Lesion formation in this animal model depends upon complement activation, mast cell degranulation and accumulation of neutrophils and eosinophils. Patients’ autoantibodies to BP180 induce dermal–epidermal separation in cryosections of human skin when co-incubated with leukocytes. The loss of cell-matrix adhesion is mediated by proteinases released by granulocytes. The increased knowledge of the pathophysiology of BP should facilitate the development of novel therapeutic strategies for this disease.     

Primary cutaneous marginal zone lymphoma (immunocytoma like) with lymphoepithelioid or Lennert's lymphoma like involvement of nodes

Primary cutaneous marginal zone lymphomas (PCMZL) have a wide range of morphology from tumors with monocytoid B cells to those composed entirely of plasma cells and the T-cell rich variants. We report a 60-year-old male with a PCMZL rich in plasma cells of the foot with a lymphoepithelioid-like pattern of dissemination to the lymph nodes posing problems in the diagnosis. The patient had a lesion on the dorsum of the foot which histologically revealed dense perivascular collections of lymphoid cells and plasma cells amidst fibrous tissue. Though the plasma cells did show light chain restriction, CD20 and CD3 did not reveal an overwhelming B/T-cell population and hence a diagnosis of a reactive process was offered. Subsequently the patient developed inguinal nodes with diffuse loss of architecture and replacement by epithelioid histiocytes and reactive T cells with few large B cells (lymphoepithelioid-like pattern). On pathology review it was realized that the two lesions may be related and clonality studies were asked for. The skin lesion showed clonally rearranged IgH receptor while the T-cell receptor rearrangement was negative. The patient developed disseminated disease and received six cycles of chemotherapy with partial response and 6 years after the initial presentation was alive with nonprogressive disease. Thus, the polymorphous background in PCMZL is evolving and an immunocytoma-like tumor can show a T-cell rich or Lennert's like growth pattern of spread and early recognition these odd patterns may aid in appropriate management of patients.     

Infiltrating T cells during liver graft-versus-host disease show a restricted T-cell repertoire.

Data from animal models have shown that hepatic graft-versus-host disease (GVHD) may be mediated by donor T cells interacting with liver adhesion molecules, other minor histocompatibility antigens, or both. We hypothesized that T-cell infiltrates within a liver biopsy during clinical GVHD would show a restricted T-cell response because the T cells would be responding to a limited number of antigens. We studied the peripheral T-cell repertoire and the liver-infiltrating T-cell repertoire of a patient who developed skin GVHD and subsequent liver GVHD after a matched sibling bone marrow transplantation for acute myeloid leukemia. Spectratype analysis of peripheral blood at the time of liver GVHD revealed that the patient had reconstituted a complex peripheral T-cell repertoire as evidenced by the presence of complementarity-determining region 3 (CDR3) length heterogeneity in most of the T-cell families. The repertoire complexity was skewed in variable gene beta (VB) 5.3, VB4, VB7, VB8, and VB15. Spectratype analysis on the liver biopsy sample revealed a limited infiltrate with an oligoclonal expansion in VBs 4, 7, and 8. We evaluated the T-cell infiltrate in more detail by sequencing the relevant expansions noted by spectratype and developing probes for the predominant CDR3 sequences. These clonotype probes were hybridized to peripheral blood and liver samples from the patient, a T-cell line developed from the patient's peripheral blood at the time of the initial skin GVHD, the donor's blood and marrow, and control samples. The results showed that the T-cell infiltrate during liver GVHD is mediated by a limited number of T cells, and that those cells are mostly different from the ones expanded from the peripheral blood during an acute skin GVHD reaction. These data support the concept that liver GVHD is a response to tissue-specific minor histocompatibility antigens.     

Protein kinase Czeta: a novel protective neonatal T-cell marker that can be upregulated by allergy prevention strategies

BACKGROUND: Variations in neonatal T-cell function have been associated with allergic disease. OBJECTIVES: To examine the relationship between neonatal T-cell protein kinase (PKC) expression and subsequent allergic disease. METHODS: T cells were purified from cord blood samples (n = 74) obtained from a cohort of mothers who received either 4 g/d fish oil or a placebo from 20 weeks of gestation. PKC expression was examined in relationship to supplementation, fatty acid levels, cytokine production, and allergic outcomes at 1 year and 2.5 years of age. RESULTS: Neonatal T-cell PKCzeta expression was lower in children who had evidence of allergic disease at 1 year (P = .001) and 2.5 years (P = .052) of age. It was also lower in children with sensitization (positive skin prick test) at each age (P = .02 and P = .072, respectively). PKCzeta expression was inversely correlated to PKCalpha (r = -0.28; P = .025), which was strongly related to IL-5 responses to allergens (ovalbumin, r = 0.59; P = .003; dust mite, r = 0.52; P = .011) at 1 year of age. Fish oil supplementation was associated with significantly higher PKCzeta expression (P = .014), whereas most other isozymes were reduced by fish oil supplementation. CONCLUSION: This is the first study to show that allergic disease is associated with altered expression of T-cell PKC isozymes in the neonatal period. It has also demonstrated that fish oil can modulate expression of PKC isozymes in a potentially favorable direction. CLINICAL IMPLICATIONS: Protein kinase Czeta should be explored further as an early marker and potential target for disease prevention.     

Update on peripheral T-cell lymphomas with T-helper phenotype: Are there too many subtypes?

Follicular helper T (T_FH) cells are the providers of T-cell help to B-cells in the development of germinal centers and for the generation of most class-switched antibodies. The markers most commonly associated with T_FH activity are IL21, IL4, CD40L, BCL6, SAP, CXCR5/CXCL13, and ICOS. T-cell lymphoma genomic studies have shown that different T-cell lymphoma types express signatures typical for T_FH cells, this including angioimmunoblastic T-cell lymphoma (AITL), a related condition termed peripheral T-cell lymphoma with T_FH phenotype and primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder.Angioimmunoblastic T-cell lymphoma is a well-established entity, a clinically aggressive disease with a survival of 30% OS after 5 years. Molecular and clinical studies have confirmed this as a well-established clinicopathological entity with relatively specific gene mutations, including mutations found in hematopoietic precursor cells and others.Peripheral T-cell lymphoma with T_FH phenotype is an associated disorder with histology of PTCL but a T_FH phenotype, as defined by the expression of 2–3 immunohistochemical markers. Molecular studies on this entity are showing a partial overlap with AITL.Primary cutaneous CD4+ small/medium lymphoproliferative disorder is an entirely different process that takes place in the skin, showing frank cytologic atypia, monoclonal TCR rearrangement and T_FH phenotype in the context of a clinically benign lesion.Here we review the main clinical, molecular and diagnostic features of these three lymphoproliferative processes.     

Angioimmunoblastic T-cell lymphoma with cutaneous involvement: a case report with subtle histologic changes and clonal T-cell proliferation

Angioimmunoblastic T-cell lymphoma is a nodal peripheral T-cell lymphoma that rarely involves the skin. We describe a 62-year-old Taiwanese man who developed a second relapse of angioimmunoblastic T-cell lymphoma with generalized erythroderma and numerous plaquelike and nodular lesions. Biopsy of the erythematous skin lesion demonstrated mild infiltrate of atypical small lymphocytes, some with clear cytoplasm. The lymphoid infiltrate was located mainly around skin appendages and in the upper dermis without epidermotropism. Immunohistochemically, these atypical lymphocytes expressed CD3. Polymerase chain reaction analysis for T-cell receptor gamma-chain gene rearrangement using paraffin section showed the same-sized monoclonal bands in the skin and 2 previous nodal biopsies. We conclude that the histologic features of angioimmunoblastic T-cell lymphoma involving skin may be very subtle, showing only mild lymphoid infiltrate. Awareness of the history of angioimmunoblastic T-cell lymphoma with ancillary studies, including clonality testing for T-cell receptor gene rearrangement, is crucial for reaching an accurate diagnosis.     

Recent advances on the 180-kDa epidermal antigen in autoimmune subepidermal bullous skin diseases

Summary The blistering skin disease bullous pemphigoid (BP) is an example of how autoantibodies from patients can be used as tools to improve our knowledge of the molecular structure of normal skin. BP autoantibodies bind to the basement membrane zone of normal human skin and usually react with two main epidermal antigens of approximately 230-kDa and 180-kDa. From recent studies, it is now established that the 180-kDa polypeptide is distinct from the 230-kDa BP antigen and is a major component of hemidesmosome. In this article, the recent data regarding the localization and structure of the epidermal 180-kDa BP antigen are reviewed in detail, together with its clinical significance, since it appears to be also a target antigen for pemphigoid (herpes) gestationis and, perhaps, cicatricial pemphigoid autoantibodies.     

Experimental bullous pemphigoid generated in mice with an antigenic epitope of the human hemidesmosomal protein BP230

Bullous pemphigoid (BP) is an IgG-mediated autoimmune blistering disease that targets the hemidesmosomal proteins BP230 and BP180. To investigate the pathogenic role of anti-BP230 antibodies, rabbit polyclonal antibodies were generated against an antigenic sequence of the human BP230 antigen (BPAG 1, 2479-2499), which shows 67% homology in the human and the mouse BP230. Purified IgG from the rabbit anti-serum was transferred subcutaneously into the dorsal skin of neonatal isogeneic CBA/Ca (CBA) mice in a dose of 5 mg (n=7) or 1.2 mg IgG/50 microl (n=16). After 24 h, 1 of the mice injected with 5 mg IgG exhibited blisters, but the dorsal skin of all 7 of them was erythematous, and gentle friction produced a fine persistent wrinkling of the epidermis in 4 mice. The mice injected with 1.2 mg IgG developed less severe symptoms. Immunohistological examinations revealed linear rabbit IgG and mouse C3 depositions along the basement membrane of the perilesional skin and subepidermal blister formation. An intradermal inflammatory reaction (granulocyte infiltration) was also detected. None of these symptoms was seen in mice injected with IgG from a control rabbit anti-serum. These findings demonstrate that antibodies against BP230 can elicit the clinical and immunopathological features of BP in neonatal mice, suggesting that anti-BP230 antibodies may possibly play a pathogenic role in this disease.     

Hepatosplenic and other gammadelta T-cell lymphomas

The 2005 Society for Hematopathology/European Association for Haematopathology Workshop session 11 was dedicated to hepatosplenic T-cell lymphoma (HSTCL). HSTCL is a rare aggressive type of extranodal lymphoma characterized by hepatosplenomegaly, bone marrow involvement, and peripheral blood cytopenias. HSTCL exhibits a distinctive pattern of infiltration; tumor cells preferentially infiltrate the sinusoids of the splenic red pulp, liver, and bone marrow. The tumor cells have a nonactivated cytotoxic T-cell immunophenotype and frequently carry a recurrent cytogenetic abnormality, isochromosome 7q. Most cases express the gammadelta T-cell receptor, but cases can have an alphabeta phenotype and are considered to be a variant of the disease. Although HSTCL is the prototype peripheral T-cell lymphoma expressing the gammadelta T-cell receptor, non-HSTCL proliferations of gammadelta T cells can involve other extranodal sites, mainly skin and mucosa. These gammadelta T-cell lymphomas display marked heterogeneity in clinical and histologic features. In contrast with HSTCL, non-HSTCL gammadelta T-cell lymphomas frequently have an activated cytotoxic phenotype and most likely are not a single disease entity.     

Autoantibody detection in bullous pemphigoid: clinical evaluation of the EUROPLUS™ Dermatology Mosaic

Bullous pemphigoid (BP) is an autoimmune blistering skin disease. Autoantibodies to BP180 and BP230 can be detected by indirect immunofluorescence (IIF) on different substrates (oesophagus, salt-split-skin, BP180-antigen dots, BP230-transfected cells) and ELISA. Here, we compared test characteristics of these test systems. We analysed sera from BP patients (n=60) in whom the clinical diagnosis had been confirmed histopathologically. The control cohort comprised sera from patients with other autoimmune-associated (n=22) or inflammatory (n=35) skin diseases. All samples were tested by IIF (EUROIMMUN? Dermatology Mosaic) and ELISA (EUROIMMUN and MBL). Anti-BP180 is best detected with BP180-antigen dots by IIF (sensitivity: 88%; specificity: 97%). As compared to IIF, the differences with both BP180 ELISA techniques are small though. Likelihood ratios (LRs) for positive and negative test results are >10 and between 0.1 and 0.2, respectively, for all test systems. Detection of anti-BP230 is highly variable (sensitivity range 38-60%; specificity range 83-98%). Only the IIF test reveals a LR for positive test results >10. Since the LRs for a negative test are all ~0.5, negative test results for anti-BP230 antibodies do not help to exclude BP. In conclusion, the multi-parameter IIF test reveals a good diagnostic performance in BP. Since this test simultaneously allows for the detection of anti-Dsg1 and anti-Dsg3 antibodies, involved in pemphigus foliaceus and vulgaris, a single test-incubation may be sufficient to differentiate between the most frequent autoimmune blistering diseases.     

Autoimmune responses in patients with linear IgA bullous dermatosis: both autoantibodies and T lymphocytes recognize the NC16A domain of the BP180 molecule

Linear IgA bullous disease (LABD) is an autoimmune skin disease characterized by subepidermal blisters and IgA autoantibodies directed against the epidermal basement membrane zone (BMZ) of the skin. Various antigens have been identified as targets of IgA autoantibodies including BP180, a type II glycoprotein that spans the BMZ and lamina lucida. Previously, we have identified a subset of LABD patients whose sera contained IgA antibodies against the 16th noncollagenous (NC16A) domain of BP180. NC16A was previously shown to harbor epitopes that are recognized by both autoantibodies and T cells from patients with bullous pemphigoid and herpes gestationis and is thought to be associated with the development of these immunobullous diseases. The aim of this study was to determine whether T lymphocytes from LABD patients with anti-NC16A IgA autoantibodies respond to epitopes in the same region of the BP180 protein. Indeed, of the four LABD patients in our study, all had T cells that specifically proliferated in response to NC16A. Moreover, two subfragments of NC16A were identified as the predominant targets of LABD T cells. Further analysis of T cell lines and clones derived from these patients revealed that these cells express a CD4 memory T cell phenotype and secrete a Th1/Th2 mixed-cytokine profile, characteristics similar to those of T cells in bullous pemphigoid patients. Our data suggest that the BP180 protein, typically the NC16A region, is the common target of both cellular and humoral immune responses in some LABD patients. This information helps to further elucidate the autoimmune mechanisms in this disease.     

Complement Inhibitor C4b-Binding Protein in Primary Sjögren's Syndrome and its Association With Other Disease Markers

A subgroup of patients suffering from primary Sjögren's syndrome (pSS) display unexplained low levels of complement components C3 and/or C4 which is associated with increased risk of non-Hodgkin's lymphoma. C4b-binding protein (C4BP) is a major fluid-phase complement inhibitor which can influence C4 and C3 levels. Therefore we analysed C4BP levels in the sera of patients with pSS to better understand the disturbances in complement in pSS. Associations with other disease markers were also investigated to define a possible role of C4BP as marker of high-risk disease course. Plasma levels of C4BP were analysed in pSS patients ( n  = 86) and in controls ( n  = 68) by ELISA. C4BP levels from 49 patients were correlated to disease activity markers and autoantibody profiles. We found that total C4BP plasma levels were significantly higher in pSS patients compared with controls. C4BP levels correlated to the acute phase response, to levels of C4 and C3 as well as to the CD4+/CD8+ T-cell ratio. C4BP levels were inversely related to IgG levels, extent of autoantibody production and global disease activity. C3dg levels, a marker of complement activation, displayed a negative correlation to C4 levels but interestingly not to C4BP levels. In conclusion, C4BP levels are increased in patients suffering from pSS proportional to their acute phase response. However, in the most active cases, with the most widespread autoantibody production, C4BP levels were decreased in parallel with levels of C3 and C4 and CD4+ T cells, suggesting that disturbed complement regulation may contribute to pathogenicity in pSS.     

A Case of Adult T-cell Leukemia/Lymphoma, Histologically Presenting CD30-Positive Large Cell Lymphoma

A 48 year old Japanese woman with adult T-cell leuke-mia/lymphoma (ATLL), histologically presenting CD30 positive large cell lymphoma is reported. The patient, who was from an ATLL endemic area in Japan, had cutaneous nodules in the head, trunk, and extremities, and cervical lymph node swelling; these had been found three months before her admission to our hospital. A biopsy specimen of a skin lesion showed diffuse large cell lymphoma; the lymphoma cells were positively stained with CD30 (Ki 1/ Ber H 2), CD4 (helper T), and CD25 (interleukin 2 receptor) antibodies. Anti HTLV-1 antibody (ATLA) was detected in the serum, and molecular cytogenetic studies of lymphoma cells showed both positive T-cell receptor rearrangement and HTLV-1 specific DNA sequences.     

A case of adult T-cell leukemia/lymphoma, histologically presenting CD30-positive large cell lymphoma.

A 48-year-old Japanese woman with adult T-cell leukemia/lymphoma (ATLL), histologically presenting CD30-positive large cell lymphoma is reported. The patient, who was from an ATLL endemic area in Japan, had cutaneous nodules in the head, trunk, and extremities, and cervical lymph node swelling; these had been found three months before her admission to our hospital. A biopsy specimen of a skin lesion showed diffuse large cell lymphoma; the lymphoma cells were positively stained with CD30 (Ki-1/Ber H-2), CD4 (helper-T), and CD25 (interleukin-2 receptor) antibodies. Anti HTLV-1 antibody (ATLA) was detected in the serum, and molecular cytogenetic studies of lymphoma cells showed both positive T-cell receptor rearrangement and HTLV-1 specific DNA sequences.     

Activation of Fc epsilon RI-positive eosinophils in bullous pemphigoid

Bullous pemphigoid (BP) is an autoimmune disease frequently occurring in elderly persons. It has been reported that 92-kDa gelatinase released from eosinophils cleaves the extracellular domain of BP180 protein, suggesting a direct role of eosinophils in bulla formation in this disease. The expression of the high-affinity IgE receptor, Fc epsilon RI, on eosinophils was examined in patient with BP. Samples of affected skin obtained from 7 patients with BP were stained immunohistochemically by the alkaline phosphatase anti-alkaline phosphatase (APAAP) method and mirror sections were examined. Eosinophils were present at a rate of 1.0-19.0% in lesions of the dermis, and the number of IgE-positive cells exceeded that of Fc epsilon RI-positive cells in all cases. These cells were not detected in the epidermis, and examination of mirror sections confirmed that the Fc epsilon RI-positive cells corresponded to eosinophils. It has been demonstrated that Fc epsilon RI-positive cells are involved in the dermal lesions of BP. The activation of eosinophils by Fc epsilon RI may participate in the pathogenesis of BP by triggering the degranulation of mast cells.     

Absence of B-cell or T-cell clonal expansion in nodular, lymphocyte predominant Hodgkin's disease

Recent studies based upon immunophenotypic data have provided strong evidence that nodular lymphocyte predominant Hodgkin's disease (NLPHD) represents an entity that is distinct from other subtypes of Hodgkin's disease (HD). In contract to other forms of HD, the predominance of B-lymphocytes in NLPHD has prompted the thesis that this lesion is actually an atypical B-cell hyperplasia or follicular center cell lymphoma. Three cases of NLPHD by restriction endonuclease analysis were studied in an attempt to identify a clonal B-cell or T-cell expansion in this disorder. DNA was extracted from these tumors and hybridized to probes for the immunoglobulin genes (C kappa, C lambda, JH) and the T-cell receptor beta chain gene. Gene rearrangements were not detectable in any of the cases. The results provide genotypic evidence that there is not a monoclonal or oligoclonal proliferation of small B-lymphocytes or T-lymphocytes in NLPHD. The possibility that the L&H Reed-Sternberg cells are monoclonal cannot be excluded because their small number is below the level of sensitivity of this technique.     

RT-PCR Based Analysis of T-Cell Receptor B Variable Region Gene Usage in Normal Human Breast Skin Resident T Lymphocytes (SRT)

The skin interfaces directly with the external environment that contains innumerable infectious agents. Therefore, an appropriate and rapid immunologic response is required to preserve internal homeostasis. An essential feature of the 'skin immuno system' (SIS) is the presence of substantial numbers of T cells in normal skin. The T-cell receptor repertoire from normal human breast skin was analysed quantitatively and qualitatively by using PCR amplification of reverse transcribed RNA, T-cell receptor BV3 and BV14 gene usage was increased in skin T lymphocytes in all individuals tested ( n  = 8) compared to peripheral blood CD4⁺ and CD8⁺ T lymphocytes from the same individuals. The T-cell receptor junctional diversity analysed by high resolution gel electrophoresis showed skin T-cell BV3 and BV14 gene usage to be predominantly polyclonal. Superantigen stimulation of T cells in human skin is considered a likely explanation of the present finding.