Perturbation of Thymocyte Development Underlies the PRRS Pandemic: A Testable Hypothesis.

Porcine reproductive and respiratory syndrome virus (PRRSV) causes immune dysregulation during the Critical Window of Immunological Development. We hypothesize that thymocyte development is altered by infected thymic antigen presenting cells (TAPCs) in the fetal/neonatal thymus that interact with double-positive thymocytes causing an acute deficiency of T cells that produces "holes" in the T cell repertoire allowing for poor recognition of PRRSV and other neonatal pathogens. The deficiency may be the result of random elimination of PRRSV-specific T cells or the generation of T cells that accept PRRSV epitopes as self-antigens. Loss of helper T cells for virus neutralizing (VN) epitopes can result in the failure of selection for B cells in lymph node germinal centers capable of producing high affinity VN antibodies. Generation of cytotoxic and regulatory T cells may also be impaired. Similar to infections with LDV, LCMV, MCMV, HIV-1 and trypanosomes, the host responds to the deficiency of pathogen-specific T cells and perhaps regulatory T cells, by "last ditch" polyclonal B cell activation. In colostrum-deprived PRRSV-infected isolator piglets, this results in hypergammaglobulinemia, which we believe to be a "red herring" that detracts attention from the thymic atrophy story, but leads to our second independent hypothesis. Since hypergammaglobulinemia has not been reported in PRRSV-infected conventionally-reared piglets, we hypothesize that this is due to the down-regulatory effect of passive maternal IgG and cytokines in porcine colostrum, especially TGFß which stimulates development of regulatory T cells (Tregs).

DNA Microarray Analysis of Submandibular Glands in IgG4-Related Disease Indicates a Role for MARCO and Other Innate Immune-Related Proteins.

IgG4-related disease (IgG4-RD) is a novel systemic disease entity characterized by elevated serum IgG4 and tissue infiltration of IgG4-positive plasma cells accompanied by severe fibrosis. Although recent studies demonstrated that innate immune cells including monocytes and macrophages might promote local fibrosis and IgG4 production, the pathological mechanism remains unclear. In this study, we sought to identify the disease-associated genes, especially innate immune molecules. Gene expression was analyzed by DNA microarray in submandibular glands (SMGs) from patients with IgG4-RD (n = 5), chronic sialoadenitis (CS) (n = 3), and controls (n = 3). Differentially expressed genes (DEGs) were validated by real-time polymerase chain reaction (PCR) and immunohistochemical staining in IgG4-RD (n = 18), CS (n = 4), Sjögren syndrome (n = 11), and controls (n = 10). Gene expression patterns in the 3 groups were quite different from each other by the pvclust method and principal components analysis. In IgG4-RD, 1028 upregulated genes and 692 downregulated genes were identified as DEGs (P < 0.05). Gene Ontology (GO) term analysis indicated that the upregulated DEGs in IgG4-RD encoded proteins involved in T/B cell activation and chemotaxis. PCR validated significantly higher expression of macrophage receptor with collagenous structure (MARCO), a pattern-recognition receptor, in IgG4-RD compared with the other groups (P < 0.01). Immunohistochemical analysis confirmed that the expression pattern of MARCO was similar to that of the M2 macrophage marker CD163. MARCO was identified as a disease-associated molecule in IgG4-RD by DNA microarray. Moreover, M2 macrophages might contribute to the initiation of IgG4-RD via MARCO.

Immune complexes regulate bone metabolism through FcRγ signalling.

Autoantibody production and immune complex (IC) formation are frequently observed in autoimmune diseases associated with bone loss. However, it has been poorly understood whether ICs regulate bone metabolism directly. Here we show that the level of osteoclastogenesis is determined by the strength of FcRγ signalling, which is dependent on the relative expression of positive and negative FcγRs (FcγRI/III/IV and IIB, respectively) as well as the availability of their ligands, ICs. Under physiological conditions, unexpectedly, FcγRIII inhibits osteoclastogenesis by depriving other osteoclastogenic Ig-like receptors of FcRγ. Fcgr2b(-/-) mice lose bone upon the onset of a hypergammaglobulinemia or the administration of IgG1 ICs, which act mainly through FcγRIII. The IgG2 IC activates osteoclastogenesis by binding to FcγRI and FcγRIV, which is induced under inflammatory conditions. These results demonstrate a link between the adaptive immunity and bone, suggesting a regulatory role for ICs in bone resorption in general, and not only in inflammatory diseases.

The injured liver induces hyperimmunoglobulinemia by failing to dispose of antigens and endotoxins in the portal system.

Hyperimmunoglobulinemia is frequently observed in patients with chronic liver diseases. However, the exact mechanism underlying the high level of antibody formation is not fully understood. In our study, we provide evidence for the functional role of the liver and the stimulation of plasma cell proliferation in hyperimmunoglobulinemia. We collected sera from patients with chronic liver diseases, and the level of serum immunoglobulins in patients was examined; this was also investigated in animal models of liver cirrhosis and hepatocellular carcinoma. An end-to-side microsurgical portacaval shunt was used to mimic liver dysfunction in rats. We used portal vein serum and inferior vena cava serum to immunize healthy rats and mice in order to confirm the function of the healthy liver in disposing of antigens and endotoxins from the gut. For the analysis of the state of plasma cell activation, plasma cells from mice were stained with PE-conjugated anti-CD138 and FITC-conjugated anti-BrdU for flow cytometry analysis. Hyperimmunoglobulinemia was observed both in patients with chronic liver diseases and in related animal models, and high plasma LPS levels were also observed. There was a significant increase in the activation and proliferation of plasma cell in mice immunized with antigens or LPS-positive serum compared with controls that were immunized with antigens and LPS-negative serum. We confirmed that the healthy liver plays an important role in disposing of antigens and endotoxins derived from the gut. Hyperimmunoglobulinemia in chronic liver diseases mainly arises due to the collateral circulation secondary to portal hypertension, gut antigens and endotoxins that bypass the liver and reach the antibody-producing cells.

[Peripheral blood CD4⁺;CXCR5⁺; follicular helper T cells are related to hyperglobulinemia of patients with chronic hepatitis B].

OBJECTIVE: To detect cell frequency and surface markers of peripheral blood CD4⁺;CXCR5⁺;follicular helper T cells (Tfh cells) and analyze the correlation between CD4⁺;CXCR5⁺;Tfh cells and hyperglobulinemia of patients with chronic hepatitis B. METHODS: We collected blood samples of 20 HBV infected patients with hyperglobulinemia, 10 chronic HBV infected patients and 10 health volunteers and isolated plasma and peripheral blood mononuclear cells (PBMCs). The percentage of CD4⁺;CXCR5⁺;Tfh cells and the expressions of PD-1, ICOS and CD40L on CD4⁺;CXCR5⁺;Tfh cells were detected by flow cytometry. The levels of CXCL13, IFN-γ and IL-21 in plasma were measured by ELISA. RESULTS: Compared with the percentage of CD4⁺;CXCR5⁺;Tfh cells in chronic HBV infected patients (11.9 ± 3.9) and health controls (6.8 ± 3.9), it was higher in HBV infected patients with hyperglobulinemia (22.6 ± 4.7, P<0.05). And in the hyperglobulinemia patients, the expressions of PD-1 and CD40L on CD4⁺;CXCR5⁺;Tfh cells and the levels of CXCL13 and IL-21 in plasma increased, whereas the level of IFN-γ significantly declined (P<0.05). CONCLUSION: The results suggest that CD4⁺;CXCR5⁺;Tfh cells may participate in the pathogenesis of hyperglobulinemia during HBV infection.

Inflammatory aortic aneurysm: possible manifestation of IgG4-related sclerosing disease.

In this study, we investigate the hypothesis that IgG4-related autoimmune reaction is involved in the formation of inflammatory aortic aneurysms (IAA). We obtained 23 cases of IAA and 11 cases of atherosclerotic aortic aneurysms (AAA) as control group. We evaluated the expression of IgG4 in both IAA study cases and AAA control cases. In addition, immunohistochemical expression of C-Kit, CD21, CD34, S-100 protein, SMA, vimentin, p53, beta-catenin, and ALK-1, and EBV-LMP1 expression by in situ hybridization were performed only in IAA cases. Of the 23 patients, 20 were males and 3 were females (M: F ratio 6.7:1); age ranged from 43 to 81 years (average 64.3 years). Histologically, all 23 cases of IAA formed a mass that displayed inflammatory myofibroblastic tumor-like features. All lesions stained strongly and diffusely for vimentin and SMA (100%); 17 stained strongly and focally for CD34 (74%); and all were negative for C-Kit, CD21, S-100 protein, p53, beta-catenin, EBV-LMP1, and ALK-1. The numbers of infiltrating IgG4-positive plasma cells in IAA cases exceed that of AAA cases. Score 3 (>50 plasma cells/one 40X field) of IgG4-positive plasma cells was only seen in IAA cases (13/23, 57%), whereas none of the 11 cases of AAA showed score 3 IgG4-positive plasma cells (P=0.0018, Fischer's exact test). Our findings suggest that IAA may be an aortic manifestation of the IgG4-related sclerosing disease. The high number of positive plasma cells, >50 plasma cells/one 40X field is more specific for the IAA than for AAA; however, lesser number can be seen in both IAA and AAA patients.

Urethral caruncle: a lesion related to IgG4-associated sclerosing disease?

AIMS: Urethral caruncle is a benign, polypoid urethral mass that occurs almost exclusively in postmenopausal women. Despite that these lesions are routinely managed with topical medications or excision, their pathogenesis is not well understood. We investigated the possibilities of autoimmune, viral and inflammatory myofibroblastic proliferations as possible aetiologies. METHODS: In 38 patients with urethral caruncle, we utilised immunohistochemistry for immunoglobulin G (IgG) and IgG4 to assess for a potential autoimmune aetiology. Immunohistochemistry was performed in nine patients for Epstein-Barr virus, BK virus, human herpesvirus 8, human papillomavirus, adenovirus and anaplastic lymphoma kinase. RESULTS: Four patients (11%) showed infiltrates of ≥50 IgG4-positive plasma cells per high power field, of which all showed an IgG4 to IgG ratio greater than 40%. A statistically significant difference (p<0.01) was detected in the mean number of IgG4-positive cells (14.73 per high power field) compared with control benign urethral specimens (mean, 1.19). One patient with increased counts below this threshold had rheumatoid arthritis; none had documented autoimmune pancreatitis or other known manifestations of systemic IgG4-related sclerosing disease. All lesions showed negative reactions for the viral and inflammatory myofibroblastic markers. CONCLUSIONS: Urethral caruncle is a benign inflammatory and fibrous polypoid urethral mass of unclear aetiology. It appears unrelated to viral infection and lacks the abnormal expression of anaplastic lymphoma kinase protein, as seen in inflammatory myofibroblastic tumours. Increased numbers of IgG4-positive plasma cells in a subset of lesions raise the possibility that some cases may be related to the autoimmune phenomena of IgG4-associated disease.

[Preliminary study of the relationship between tumor like Sjögren's syndrome and malignant lymphoma].

OBJECTIVE: To investigate the clinical and laboratory characteristics of tumor like Sjögren's syndrome (TLSS) patients and non-tumor like Sjögren's syndrome (NTLSS) and the incidence of lymphoma in patients of Sjögren's syndrome (SS). METHODS: A retrospective analysis was carried out in 199 primary SS (including TLSS) patients who were recruited in Peking University School and Hospital of Stomatology from 1998 to 2010. Clinical and laboratory information were collected. The patients were divided into two groups: TLSS (n = 25) and NTLSS (n = 174). Clinical and laboratory characteristics were compared between these two groups by a statistical analysis. RESULTS: Of the 25 TLSS patients, 23 had enlargements of parotid glands and 2 had enlargements of submandibular glands. There were significant differences of salivary scintigraphy appearance (P = 0.018), hypergammaglobulinemia (P = 0.014), rheumatoid factor positive rate (P = 0.001), formation of the ectopic germinal centers (P = 0.014), double positive rate of anti-SSA antibody and anti-SSB antibody (P < 0.001) between the TLSS and NTLSS patients. Among the 25 TLSS patients, 3 developed lymphomas, accounting for 1.5% (3/199) of the total 199 patients and 12% (3/25) of the TLSS patients. Lymphoma subtypes included one diffused large B-cell lymphoma and two mucosa-associated lymphoid tissue lymphoma. There was no lymphoma detected in NTLSS patients. CONCLUSIONS: There are clinical and laboratory differences between TLSS and NTLSS patients, with a more tendency to develop lymphomas in TLSS patients.

Rheumatoid lymphadenopathy with abundant IgG4(+) plasma cells : a case mimicking IgG4-related disease.

Immunoglobulin (Ig) G4-related disease is a recently confirmed clinical entity with several unique clinicopathological features. Here we report a case of rheumatoid lymphadenopathy mimicking IgG4-related disease. The patient was a 63-year-old woman who had been treated for rheumatoid arthritis (RA) for six years. The patient noted cervical lymphadenopathy. Upon radiological examination, systemic lymphadenopathy was detected, and enlarged right brachial lymph node biopsy was performed. Histologically, the lymph node showed marked follicular hyperplasia and interfollicular plasmacytosis without eosinophil infiltration. Although the histological findings were compatible with rheumatoid lymphadenopathy, numerous plasma cells were IgG4(+) (IgG4(+)/IgG(+) plasma cell ratio > 50%). However, laboratory findings revealed elevation of C-reactive protein level, polyclonal hyper-γ-globulinemia, anemia, and hypoalbuminemia. These findings were compatible with hyper-interleukin (IL)-6 syndrome, namely, RA. It is known that hyper-IL-6 syndromes, such as multicentric Castleman's disease, RA, and other autoimmune diseases, fulfill the histological diagnostic criteria for IgG4-related disease. Therefore, hyper-IL-6 syndromes and IgG4-related disease cannot be differentially diagnosed by immunohistochemical staining alone. In conclusion, rheumatoid lymphadenopathy sometimes occurs with abundant IgG4(+) plasma cells, which is required for the differential diagnosis of IgG4-related disease.

The immunobiology and clinical characteristics of IgG4 related diseases.

Having the characteristic features of elevated serum IgG4 levels and prominent infiltration of IgG4-positive plasma cells with fibrosis in lesions, Mikulicz's disease (MD) has been recognized as an IgG4-related disease (IgG4-RD). Although incidence of autoimmune pancreatitis (AIP), one of the organ characteristics of IgG4-RD, has been internationally reported, there are only a few such reports of IgG4-related MD. The limited number of reports might be attributable to the low recognition of IgG4-related MD as a clinical entity as well as its misdiagnosis as Sjögren's syndrome (SS). Thus, we compared several clinical features of MD with SS to improve proper clinical diagnosis of MD in the clinical setting. A total of 70 SS and 70 MD cases evaluated at Sapporo Medical University Hospital were retrospectively analyzed. In SS patients, sicca symptoms were the most frequent (87%), followed by articular symptoms (23%), while lacrimal and salivary gland swelling were a rare (10%) and transient manifestation. In contrast, lacrimal or salivary gland swelling was observed in all patients with MD. Although nearly 60% of MD patients complained of sicca syndrome, skin rash and arthralgia were rare symptoms. Hypergammaglobulinemia was recognized in both SS and MD patients, but the occurrence of autoantibodies in patients with IgG4-related MD was low. Extraglandular organ involvement, often involving the retroperitoneum, pancreas, kidney and lung, was often discovered at the time of IgG4-related MD diagnosis. Although corticosteroid therapy tended to delay the hypofunction of salivary gland in SS patients, recovery of decreased function of salivary glands were observed in IgG4-related MD patients. These results suggest the beneficial effect of aggressive corticosteroid intervention in patients with IgG4-related MD. Although SS and MD are both chronic inflammatory diseases affecting the lacrimal and salivary glands, their clinical features and corticosteroid responsiveness are different. Thus, differential diagnosis of these conditions is warranted.

A novel transgenic mouse model of the human multiple myeloma chromosomal translocation t(14;16)(q32;q23).

Multiple myeloma (MM) is a currently incurable neoplasm of terminally differentiated B cells. The translocation and/or overexpression of c-MAF have been observed in human MM. Although c-MAF might function as an oncogene in human MM, there has been no report thus far describing the direct induction of MM by c-MAF overexpression in vivo. In this study, we have generated transgenic (TG) mice that express c-Maf specifically in the B-cell compartment. Aged c-Maf TG mice developed B-cell lymphomas with some clinical features that resembled those of MM, namely, plasma cell expansion and hyperglobulinemia. Quantitative RT-PCR analysis demonstrated that Ccnd2 and Itgb7, which are known target genes of c-Maf, were highly expressed in the lymphoma cells. This novel TG mouse model of the human MM t(14;16)(q32;q23) chromosomal translocation should serve to provide new insight into the role of c-MAF in tumorigenesis.

Elevated serum levels of a proliferation-inducing ligand in patients with systemic sclerosis: possible association with myositis?

OBJECTIVE: A proliferation-inducing ligand (APRIL) is a new member of the tumour necrosis factor family which is intimately connected to the regulation of cellular pathways. The aim of this study was to assess serum concentrations of APRIL in systemic sclerosis patients, and to correlate them with the main clinical and serological features of the disease. METHODS: Sera from 35 patients with systemic sclerosis, 25 had limited cutaneous and 10 had diffuse cutaneous subtypes, and 35 normal healthy subjects were assayed for APRIL by Enzyme Linked Immunosorbant Assay. Demographic, clinical, autoantibodies and serological data were prospectively assessed. RESULTS: Serum APRIL concentrations were higher in patients with systemic sclerosis and in both its subtypes compared to the healthy controls (p<0.0001 in all). Patients with elevated APRIL levels had significantly higher incidences of myositis than those with normal levels (p=0.04). We did not find significant differences in other organ involvement prevalence between systemic sclerosis patients with elevated vs. normal APRIL levels. In addition, the frequencies of autoantibodies (i.e., anti-topoisomerase I, anti-centromere) were comparable between both groups. Serum APRIL levels were correlated with serum γ-globulins concentrations (r=0.404, p=0.016) but not with C-reactive protein, skin score, nor pulmonary functions. Serum APRIL was also correlated with creatine kinase levels only in systemic sclerosis patients with myositis (r=0.786, p=0.02). CONCLUSION: Our preliminary results suggest increased serum APRIL levels in systemic sclerosis patients, particularly in those associated with myositis and hypergammaglobinemia. To confirm our results, we propose that larger scale, multicentre studies with longer evaluation periods are needed.

Ultrastructural immunolabeling in the diagnosis of monoclonal light-and heavy-chain-related renal diseases.

Renal dysfunction is often seen in patients with plasma cell dyscrasias. The abnormal light and heavy chains that are produced by the neoplastic plasma cells in these patients are responsible for the renal abnormalities that occur. The renal manifestations are heterogeneous and include alterations in all three renal compartments; sometimes more than one compartment is affected in a given case. It must be demonstrated that the renal abnormalities are directly related to the underlying plasma cell dyscrasia to make a definitive diagnosis of an associated lesion. Therefore, it becomes crucial to link the renal findings with the circulating nephrotoxic light or heavy chains. Immunofluorescence is very helpful and diagnostic in the majority of the cases, as it can localize the light or heavy chains to the various renal compartments showing alterations, and frequently confirm monoclonality. However, the antibodies that are used routinely do not necessarily label the abnormal light and heavy chains; the corollary of this is that a negative immunofluorescence workup does not rule out a light- or heavy-chain-related renal disorder. Electron microscopy is also important as it can depict crucial morphologic correlates to provide unique evidence or to simply confirm and clarify diagnostic findings. Ultrastructural immunolabeling combines the information obtained from immunofluorescence and electron microscopy by highlighting specific structures associated with the deposition of the pathogenic monotypical light and heavy chains.

Membrane-bound Fas ligand only is essential for Fas-induced apoptosis.

Fas ligand (FasL), an apoptosis-inducing member of the TNF cytokine family, and its receptor Fas are critical for the shutdown of chronic immune responses and prevention of autoimmunity. Accordingly, mutations in their genes cause severe lymphadenopathy and autoimmune disease in mice and humans. FasL function is regulated by deposition in the plasma membrane and metalloprotease-mediated shedding. Here we generated gene-targeted mice that selectively lack either secreted FasL (sFasL) or membrane-bound FasL (mFasL) to resolve which of these forms is required for cell killing and to explore their hypothesized non-apoptotic activities. Mice lacking sFasL (FasL(Deltas/Deltas)) appeared normal and their T cells readily killed target cells, whereas T cells lacking mFasL (FasL(Deltam/Deltam)) could not kill cells through Fas activation. FasL(Deltam/Deltam) mice developed lymphadenopathy and hyper-gammaglobulinaemia, similar to FasL(gld/gld) mice, which express a mutant form of FasL that cannot bind Fas, but surprisingly, FasL(Deltam/Deltam) mice (on a C57BL/6 background) succumbed to systemic lupus erythematosus (SLE)-like autoimmune kidney destruction and histiocytic sarcoma, diseases that occur only rarely and much later in FasL(gld/gld) mice. These results demonstrate that mFasL is essential for cytotoxic activity and constitutes the guardian against lymphadenopathy, autoimmunity and cancer, whereas excess sFasL appears to promote autoimmunity and tumorigenesis through non-apoptotic activities.

Development of autoimmune hepatitis-like disease and production of autoantibodies to nuclear antigens in mice lacking B and T lymphocyte attenuator.

OBJECTIVE: B and T lymphocyte attenuator (BTLA), a coreceptor expressed on lymphocytes, was recently described as an inhibitory coreceptor that negatively regulates lymphocyte activation. The purpose of this study was to investigate the role of BTLA in the regulation of immune homeostasis and the pathogenesis of autoimmunity. METHODS: We examined the levels of immunoglobulins and autoantibodies to nuclear antigens and the activation status of T cells in BTLA(-/-) mice. We also examined histopathologic changes in the organs of BTLA(-/-) mice. RESULTS: We observed that BTLA(-/-) mice gradually developed hypergammaglobulinemia, antinuclear antibodies, anti-SSA antibodies, anti-double-stranded DNA antibodies, and an increased number of activated CD4+ T cells in the periphery with age. Lack of BTLA led to spontaneous development of autoimmune hepatitis-like disease characterized by an elevation in the level of transaminases, interface hepatitis, and spotty necrosis of the liver. BTLA(-/-) mice also showed inflammatory cell infiltration of multiple organs, including the salivary glands, lungs, and pancreas; these features are similar to those of Sjögren's syndrome, which is a frequent complication of autoimmune hepatitis. Furthermore, the survival rate of BTLA(-/-) mice was significantly reduced after the age of 7 months. CONCLUSION: Our results indicate that BTLA plays an important role in the maintenance of immune tolerance and the prevention of autoimmune diseases.

Lymphoplasmacytic infiltrate of regional lymph nodes in Kuttner's tumor (chronic sclerosing sialadenitis): a report of 3 cases.

Regional lymph nodes of Küttner's tumor from 3 patients showed reactive follicular hyperplasia and prominent interfollicular plasmacytosis. The patients were 71-, 57-, and 73-year-old Japanese men. The polytypic nature of plasma cells was demonstrated by immunohistochemistry. There were numerous IgG-positive plasma cells with scattered IgA-positive or IgM-positive plasma cells. IgG4-positive cells comprised 25% to 40% of IgG-positive plasma cells. Prominent polyclonal hyperimmunoglobulinemia was demonstrated on laboratory test in 2 cases examined. An elevated serum IgG4 level (16%) was also demonstrated in 1 patient. The present 3 cases indicated that regional lymph node of Küttner's tumor may show reactive follicular hyperplasia and prominent interfollicular plasmacytosis and should be differentiated from various benign and malignant lymphoproliferative disorders including systemic rheumatic disease, plasma cell type of Castleman disease, and lymph node involvement of marginal B-cell lymphoma of the mucosa-associated lymphoid tissue type showing prominent plasma cell differentiation.

Introduction of a CD40L genomic fragment via a human artificial chromosome vector permits cell-type-specific gene expression and induces immunoglobulin secretion.

Gene therapy using cDNA driven by an exogenous promoter is not suited for genetic disorders that require intrinsic expression of a transgene, such as hyperimmunoglobulin (Ig)M syndrome (HIGM), which is caused by mutations in the CD40L gene. The human artificial chromosome (HAC) vector has the potential to solve this problem, because it can be used to transfer large genomic fragments containing their own regulatory elements. In this study, we examined whether introduction of a genomic fragment of CD40L via the HAC vector permits intrinsic expression of the transgene and has an effect on immunoglobulin secretion. We constructed an HAC vector carrying the mouse CD40L genomic fragment (mCD40L-HAC) in Chinese hamster ovary (CHO) cells and transferred the mCD40L-HAC vector into a human CD4-positive active T-cell line (Jurkat) and a human myeloid cell line (U937) via microcell-mediated chromosome transfer (MMCT). The mCD40L-HAC vector permits mCD40L expression in human active T cells but not in human myeloid cells. The mCD40L-HAC also functions to stimulate mouse B cells derived from CD40L(-/-) mice, inducing secretion of IgG. This study may be an initial step toward the therapeutic application of HAC vectors for intrinsic expression of genes, a potential new direction for genome-based gene therapy.

Pulmonary lesion of idiopathic plasmacytic lymphadenopathy with polyclonal hyperimmunoglobulinemia appears to be a cause of lymphoplasmacytic proliferation of the lung: a report of five cases.

We report on pulmonary lesions seen in five cases of idiopathic plasmacytic lymphadenopathy with polyclonal hyperimmunoglobulinemia (IPL). This group of five patients consisted of two Japanese men (age: 33 and 45 years), and three Japanese women (age: 25, 43, and 48 years). All five cases were detected incidentally on routine chest X-rays, and had multiple small nodular lesions in the bilateral lungs. These pulmonary lesions were the initial clinical presentation of IPL in three cases in which, at the onset of disease, no lymphadenopathy was detected. At the disease onset, all five cases showed prominent IPL. In three cases examined, serum interleukin-6 was elevated, and anti-human immunodeficiency type-1 antibody was negative in three cases. Clinically, autoimmune disease was suspected for all five cases, and the various autoantibodies were investigated. Although anti-Scl 70 antibody was positive in one case, this patient had no symptoms of systemic sclerosis. Pathologically, all five lesions were characterized by well-demarcated masses that consisted of abundant reactive germinal centers and a dense lymphoplasmacytic infiltrate in the interfollicular area with a variable degree of interfollicular fibrosis. The immunohistochemical study and polymerase chain reaction demonstrated the polytypic nature of the plasma cells and B-cells. IPL is rare in lymphoproliferative disorders. However, pulmonary involvement may frequently occur in IPL patients. Moreover, pulmonary involvement seems to represent the initial clinical manifestation of IPL. Therapeutically, it is important to discriminate between pulmonary involvement of IPL and pulmonary benign or malignant pulmonary lymphoplasmacytic proliferation, particularly marginal zone B-cell lymphoma of the mucosa-associated lymphoid tissue type.