Differential pulmonary toxicity and autoantibody formation in genetically distinct mouse strains following combined exposure to silica and diesel exhaust particles.

BACKGROUND: Inhalation of airborne particulate matter, such as silica and diesel exhaust particles, poses serious long-term respiratory and systemic health risks. Silica exposure can lead to silicosis and systemic autoimmune diseases, while DEP exposure is linked to asthma and cancer. Combined exposure to silica and DEP, common in mining, may have more severe effects. This study investigates the separate and combined effects of occupational-level silica and ambient-level DEP on lung injury, inflammation, and autoantibody formation in two genetically distinct mouse strains, thereby aiming at understanding the interplay between genetic susceptibility, particulate exposure, and disease outcomes. Silica and diesel exhaust particles were administered to mice via oropharyngeal aspiration. Assessments of lung injury and host response included in vivo lung micro-computed tomography, lung function tests, bronchoalveolar lavage fluid analysis including inflammatory cytokines and antinuclear antibodies, and histopathology with particle colocalization. RESULTS: The findings highlight the distinct effects of silica and diesel exhaust particles (DEP) on lung injury, inflammation, and autoantibody formation in C57BL/6J and NOD/ShiLtJ mice. Silica exposure elicited a well-established inflammatory response marked by inflammatory infiltrates, release of cytokines, and chemokines, alongside mild fibrosis, indicated by collagen deposition in the lungs of both C57BL/6J and NOD/ShilLtJ mice. Notably, these strains exhibited divergent responses in terms of respiratory function and lung volumes, as assessed through micro-computed tomography. Additionally, silica exposure induced airway hyperreactivity and elevated antinuclear antibody levels in bronchoalveolar lavage fluid, particularly prominent in NOD/ShiLtJ mice. Moreover, antinuclear antibodies correlated with extent of lung inflammation in NOD/ShiLTJ mice. Lung tissue analysis revealed DEP loaded macrophages and co-localization of silica and DEP particles. However, aside from contributing to airway hyperreactivity specifically in NOD/ShiLtJ mice, the ambient-level DEP did not significantly amplify the effects induced by silica. There was no evidence of synergistic or additive interaction between these specific doses of silica and DEP in inducing lung damage or inflammation in either of the mouse strains. CONCLUSION: Mouse strain variations exerted a substantial influence on the development of silica induced lung alterations. Furthermore, the additional impact of ambient-level DEP on these silica-induced effects was minimal.

ENT2 facilitates brain endothelial cell penetration and blood-brain barrier transport by a tumor-targeting anti-DNA autoantibody.

The blood-brain barrier (BBB) prevents antibodies from penetrating the CNS and limits conventional antibody-based approaches to brain tumors. We now show that ENT2, a transporter that regulates nucleoside flux at the BBB, may offer an unexpected path to circumventing this barrier to allow targeting of brain tumors with an anti-DNA autoantibody. Deoxymab-1 (DX1) is a DNA-damaging autoantibody that localizes to tumors and is synthetically lethal to cancer cells with defects in the DNA damage response. We found that DX1 penetrated brain endothelial cells and crossed the BBB, and mechanistic studies identify ENT2 as the key transporter. In efficacy studies, DX1 crosses the BBB to suppress orthotopic glioblastoma and breast cancer brain metastases. ENT2-linked transport of autoantibodies across the BBB has potential to be exploited in brain tumor immunotherapy, and its discovery raises hypotheses on actionable mechanisms of CNS penetration by neurotoxic autoantibodies in CNS lupus.

Low-Molecular-Weight Heparin Enhanced Therapeutic Effects of Human Adipose-Derived Stem Cell Administration in a Mouse Model of Lupus Nephritis.

Background: Lupus nephritis is a life-threatening complication in systemic lupus erythematosus (SLE), but the efficiency of current therapies involving corticosteroids, immunosuppressants, and biological agents is limited. Adipose-derived mesenchymal stem cells (ASCs) are gaining attention as a novel treatment for inflammation in SLE. Low-molecular-weight heparin (LMWH) exhibits multiple functions including anti-inflammatory, anti-fibrotic, and cell function-promoting effects. LMWH stimulation is expected to increase the therapeutic effect of ASCs by promoting cellular functions. In this study, we investigated the effects of LMWH on ASC functions and the therapeutic effect of LMWH-activated human-ASCs (hep-hASCs) in an SLE mouse model. Methods: The cellular functions of human-derived ASCs stimulated with different LMWH concentrations were observed, and the optimum LMWH dose was selected. The mice were assigned to control, human-ASC, and hep-hASC groups; treatments were performed on week 20. Twenty-six week-old mice were sacrificed, and urine protein score, serum blood urea nitrogen, creatinine (Cr), anti-ds DNA IgG antibody, and serum IL-6 levels were analyzed in each group. Mice kidneys were evaluated via histological examination, immunohistochemical staining, and gene expression levels. Results: LMWH significantly promoted ASC migration and proliferation and hepatocyte growth factor production and upregulated immunomodulatory factors in vitro. Hep-hASC administration resulted in significant disease activity improvement including proteinuria, serum Cr and IL-6 levels, anti-ds DNA IgG antibody, glomerulonephritis, and immune complex in mice. Inflammation and fibrosis in kidneys was significantly suppressed in the hep-hASC group; the gene expression levels of TNF-alpha, TIMP-2, and MMP-2 was significantly downregulated in the hep-hASC group compared with the control group. Conclusions: Hep-hASC exhibited higher anti-inflammatory and anti-fibrotic effects than hASCs and may be a candidate tool for SLE treatment in future.

A nucleolytic lupus autoantibody is toxic to BRCA2-deficient cancer cells.

Cancer cells with defects in DNA repair are highly susceptible to DNA-damaging agents, but delivery of therapeutic agents into cell nuclei can be challenging. A subset of lupus autoantibodies is associated with nucleolytic activity, and some of these antibodies are capable of nuclear penetration. We hypothesized that such antibodies might have potential as therapeutic agents targeted towards DNA repair-deficient malignancies. We identified the lupus autoantibody 5C6 as a cell-penetrating nucleolytic antibody and found that 5C6 has a differential effect on a matched pair of BRCA2-proficient and deficient DLD1 colon cancer cells. 5C6 selectively induced γH2AX in, and suppressed the growth of, the BRCA2-deficient cells. These findings demonstrate the potential utility of 5C6 in targeted therapy for DNA repair-deficient malignancies and strengthen the rationale for studies of additional lupus autoantibodies in order to identify the best candidates for development as therapeutic agents. In addition, the toxic effect of 5C6 on BRCA2-deficient cells provides further support for the hypothesis that some lupus autoantibodies contribute to the lower risk of specific cancers associated with systemic lupus erythematosus.

Association of human papilloma virus with atypical and malignant oral papillary lesions.

OBJECTIVE: This study aimed to examine atypical and malignant papillary oral lesions for low- and high-risk human papillomavirus (HPV) infection and to correlate HPV infection with clinical and pathologic features. STUDY DESIGN: Sections of 28 atypical papillary lesions (APLs) and 14 malignant papillary lesions (MPLs) were examined for HPV by in situ hybridization and for p16 and MIB-1 by immunohistochemistry; 24 conventional papillomas were studied for comparison. RESULTS: Low-risk HPV was found in 10 of 66 cases, including 9 APLs and 1 papilloma. All low-risk HPV-positive cases showed suprabasilar MIB-1 staining, and the agreement was statistically significant (P < .0001). Diffuse p16 staining combined with high-risk HPV was not seen in any of the cases. A subset of HPV(-) APLs progressed to carcinoma. CONCLUSIONS: Oral papillary lesions are a heterogeneous group. Low-risk HPV infection is associated with a subset of APLs with a benign clinical course. Potentially malignant APLs and MPLs are not associated with low- or high-risk HPV.

Induction of TNF-alpha-converting enzyme-ectodomain shedding by pathogenic autoantibodies.

The release of the soluble form of tumor necrosis factor (TNF)-alpha from the plasma membrane occurs through the activation of the secretase tumor necrosis factor-alpha-converting enzyme (TACE). The current study was designed to examine whether the anti-Ro/SSA autoantibodies (Abs) are capable to regulate TACE expression in non-neoplastic human salivary gland epithelial cells (SGEC) cultures. We investigated the effect of anti-Ro/SSA Abs on the localization and abundance of cell-surface TACE and on TACE pro-domain-shedding and activation. In addition, the potential physiological consequences of TNF-alpha blockage by the biological agent Adalimumab on post-translational regulation of TACE are discussed. Anti-Ro/SSA Abs were purified from IgG fractions of patients with primary Sjögren's syndrome, using Sepharose 4B-Ro/SSA affinity columns. Flow cytometry, reverse transcription-PCR, western blot and immunohistochemistry were used to study TACE expression on SGEC and TACE regulation by Abs. Our study demonstrated a dose-dependent increase of TACE messenger RNA (mRNA) expression in anti-Ro/SSA Abs-treated SGEC, followed by internalization, pro-domain shedding and activation of TACE protein, suggesting that increased TACE activity is necessary for the release of TNF-alpha observed in anti-Ro/SSA Abs-stimulated SGEC. Adalimumab treatment brought TACE mRNA and surface TACE expression to levels than those observed in untreated SGEC. These data suggest that the effect of anti-Ro/SSA Abs on TACE expression and intracellular distribution is exerted by TNF-alpha production.

Tumor necrosis factor inhibitors block apoptosis of human epithelial cells of the salivary glands.

Inhibition of tumor necrosis factor-alpha (TNF-alpha) in organ-specific autoimmune disease is proving efficacious for a large number of patients. A wide array of biological agents has been designed to inhibit TNF-alpha, such as adalimumab (fully humanized) and etanercept (soluble TNF-alpha receptor fusion constructs p75 subunit). Recently, we suggested that anti-Ro and anti-La autoantibodies (Abs) isolated from patients with Sjögren's syndrome, an autoimmune rheumatic disease, are able to trigger cell death through extrinsic apoptotic mechanisms in human salivary gland epithelial cells (SGEC). We analyzed if primary human SGEC cultures, established from biopsy of labial minor salivary glands, are able to produce TNF-alpha, an inductor of the extrinsic apoptotic pathway, when treated with anti-Ro autoantibodies. A comparative study was performed to test the efficacy of adalimumab and etanercept to block TNF-alpha-mediated apoptosis. ELISA assay and RT-PCR were employed to visualize TNF-alpha production, and apoptosis was evaluated by DNA ladder and flow cytometry. We found that cell treatment with anti-Ro autoantibodies determines TNF-alpha production that reaches a maximum at 16 h and is decreased (P < 0.05) at 24 and 48 h. Adalimumab seems to be more efficacious than etanercept in blocking TNF-alpha-mediated apoptosis. The YOPRO-1 (+) and propidium iodide (-) method revealed 60% of apoptotic cells after 24 h of incubation with anti-Ro compared with 15% of apoptotic cells treated with anti-Ro plus adalimumab and 25% of apoptotic cells treated with anti-Ro plus etanercept. The antiapoptotic effect of adalimumab and etanercept was supported by inhibition of DNA laddering induced by anti-Ro Abs. These data validate the therapeutic efficacy of the anti-TNF reagents in the treatment of autoimmune disorders.

Anti-DNA antibody induction of protein kinase C phosphorylation and fibronectin synthesis in human and murine lupus and the effect of mycophenolic acid.

OBJECTIVE: To examine fibronectin (FN) expression in human lupus nephritis and the effect of anti-DNA antibodies on transforming growth factor beta1 (TGFbeta1) and FN synthesis in cultured human mesangial cells. The effects of mycophenolic acid (MPA) on this pathway, and the effects of mycophenolate mofetil (MMF) treatment in (NZB x NZW)F(1)/J mice were also studied. METHODS: Immunohistochemical analyses of renal biopsy samples from patients with active diffuse proliferative lupus nephritis were performed. Cultured human mesangial cells were incubated with human polyclonal anti-DNA antibodies, with or without MPA. (NZB x NZW)F(1)/J mice with active nephritis were randomized to receive either MMF (100 mg/kg/day) or vehicle treatment for 12 weeks. RESULTS: Glomerular FN expression was increased in patients with lupus nephritis, and it colocalized with IgG deposition. Anti-DNA antibodies induced protein kinase Calpha (PKCalpha), PKCbetaI, and PKCbetaII activation, increased levels of bioactive TGFbeta1, and increased FN synthesis in human mesangial cells (P < 0.001 for each comparison versus control conditions). Pretreatment of anti-DNA antibodies with exogenous DNA reduced their cellular binding and abrogated their induction of TGFbeta1 and FN synthesis. Inhibition of PKC activation in human mesangial cells prior to anti-DNA antibody stimulation had no effect on cell proliferation, but resulted in significantly reduced antibody-mediated TGFbeta1 secretion and FN synthesis. MPA treatment down-regulated PKCalpha, PKCbetaI, and PKCbetaII phosphorylation, reduced levels of TGFbeta1 bioactivation, and decreased FN synthesis and deposition into the extracellular matrix. MMF treatment in (NZB x NZW)F(1)/J mice resulted in a reduction in glomerular IgG deposition, PKC activation, and FN expression, as well as an amelioration of proteinuria. CONCLUSION: Human polyclonal anti-DNA antibodies induce TGFbeta1 and FN synthesis in human mesangial cells through PKC activation, which is inhibited by MPA.

Anti-DNA Ig peptides promote Treg cell activity in systemic lupus erythematosus patients.

OBJECTIVE: Treg cells oppose autoreactive responses in several autoimmune diseases, and their frequency is reduced in systemic lupus erythematosus (SLE). In murine lupus models, treatment with anti-DNA Ig-based peptides can expand the number of Treg cells in vivo. This study was undertaken to test the possibility that functional human Treg cells can be induced by exposure to anti-DNA Ig-based peptides. METHODS: Peripheral blood mononuclear cells were isolated from 36 lupus patients and 32 healthy individuals matched for ethnicity, sex, and age. Short-term culture experiments in the presence of several independent stimuli including anti-DNA Ig peptides were followed by flow cytometric analysis for identification of CD4+,CD25(high) T cells, cell sorting for in vitro suppression assays, and analysis of correlations between the expression of forkhead box P3 (FoxP3) and serologic and clinical characteristics of the SLE patients. RESULTS: The number of in vitro CD4+,CD25(high) T cells increased after culture with anti-DNA Ig peptides in the SLE patients, but not in the controls. The expanded CD4+,CD25(high) T cells required FoxP3 for cell contact-mediated suppression of proliferation and interferon-gamma production in target CD4+,CD25- T cells. The induction of FoxP3 in SLE Treg cells occurred only in seropositive patients, and was correlated with anti-DNA and IgG serum titers. CONCLUSION: These results suggest a new modality to reverse the functional deficit of Treg cells in SLE patients with positive autoimmune serology, and identify a new strategy to enhance immunoregulatory T cell activity in human SLE.

Anti-Ro and anti-La autoantibodies induce TNF-alpha production by human salivary gland cells: an in vitro study.

In this report, we demonstrate that both TNFR1 and the TNFR2 are expressed on the salivary gland cell line A-253 cell membrane. Furthermore, cell treatment with anti-Ro and anti-La autoantibodies from Sjögren IgG determined TNF-alpha production, clarifying which could be the inducer of the extrinsic pathway of apoptosis in salivary gland cells.

Nephritogenic anti-DNA antibodies regulate gene expression in MRL/lpr mouse glomerular mesangial cells.

OBJECTIVE: Lupus-associated IgG anti-double-stranded DNA antibodies are thought to be pathogenic in the kidney due to cross-reaction with glomerular antigens, leading subsequently to immune complex formation in situ and complement activation. We undertook this study to determine if pathogenic anti-DNA antibodies may also contribute to renal damage by directly influencing mesangial gene expression. METHODS: Complementary DNA microarray gene profiling was performed in primary mesangial cells (derived from lupus-prone MRL/lpr mice) treated with pathogenic, noncomplexed anti-DNA antibodies. Significant gene up-regulation induced by anti-DNA antibodies as determined by microarray analysis was further investigated by real-time polymerase chain reaction and methods to detect the relevant proteins. Induction of proinflammatory genes by pathogenic antibodies was confirmed by comparing gene expression in glomeruli of old versus young MRL/lpr mice, and by antibody injection in vivo. RESULTS: Pathogenic, but not nonpathogenic, antibodies significantly induced a number of transcripts, including CXCL1/KC, LCN2, iNOS, CX3CL1/fractalkine, SERPINA3G, and IkappaBalpha ("marker genes"). Blocking of Fcgamma receptors or using Fcgamma chain-knockout mesangial cells had no effect on the gene regulation effect of the pathogenic antibody R4A, indicating a non-Fc-dependent mechanism. The glomerular expression of these marker genes increased over time with the development of glomerular antibody deposition and active nephritis in MRL/lpr mice. Moreover, injection of R4A into SCID mice in vivo significantly up-regulated glomerular marker gene expression. CONCLUSION: These findings indicate that the renal pathogenicity of anti-DNA antibodies may be attributed in part to their ability to directly modulate gene expression in kidney mesangial cells through both Fc-dependent and non-Fc-dependent mechanisms.

U1 small nuclear ribonucleoprotein immune complexes induce type I interferon in plasmacytoid dendritic cells through TLR7.

Plasmacytoid dendritic cells (PDCs), which produce IFN-alpha in response to autoimmune complexes containing nuclear antigens, are thought to be critically involved in the pathogenesis of systemic lupus erythematosus (SLE). One of the immunostimulatory components of SLE immune complexes (SLE-ICs) is self DNA, which is recognized through Tlr9 in PDCs and B cells. Small nuclear ribonucleoproteins (snRNPs) are another major component of SLE-ICs in 30% to 40% of patients. In this study, we show that murine PDCs are activated by purified U1snRNP/anti-Sm ICs to produce IFN-alpha and proinflammatory cytokines and to up-regulate costimulatory molecules. The induction of IFN-alpha and IL-6 by U1snRNPs in murine bone marrow-derived PDCs required the presence of intact U1RNA and was largely dependent on Tlr7 but independent of Tlr3. Intracellularly delivered isolated U1snRNA and oligoribonucleotides derived from the stem loop regions and the Sm-binding site of U1snRNA efficiently induced IFN-alpha and IL-6 in Flt3L-cultured DCs in a Tlr7-dependent manner. The U1snRNA component of U1snRNP immune complexes, found in patients with SLE, acts as an endogenous "self" ligand for Tlr7 and triggers IFN-alpha and IL-6 production in PDCs.

Proliferative, infiltrative, and metastatic activities in colorectal tumors assessed by MIB-1 antibody.

MIB-1 antibody staining discriminates the cells in phases other than G0 of the cell cycle. The current study examined the proliferative activity assessed by MIB-1 antibody in colorectal adenoma, primary lesions of colorectal carcinoma (CRC) to investigate the relation between the histologic atypia, the proliferative, infiltrative, and metastatic activities. The MIB-1 antibody positive rate was immunohistologically determined in primary lesions in 311 patients, 22 having adenoma or carcinoma in situ, 207 invasive CRC without distant metastasis, and 82 invasive CRC with distant metastasis. The MIB-1 antibody positive rate was significantly higher in cases of adenoma with severe atypia and carcinoma in situ, showing a close relation between histologic atypia and proliferative activity. Among invasive CRC, the positive rate in poorly differentiated adenocarcinoma and mucinous carcinoma is significantly lower than in well differentiated and moderately differentiated adenocarcinomas. The positive rate was significantly lower in carcinomas with subserosa or deeper invasion than in carcinomas with submucosa or muscularis propria invasion, showing no distinct relation between the proliferative activity and the infiltrative activity. The positive rate of primary lesion was significantly lower in cases with metachronous liver or lung metastasis than in synchronous cases, indicating that metachronous hematogenous metastasis occurs even in cancers with low proliferative activity. The MIB-1 antibody positive rate showed a close relation between histologic atypia and proliferative activity in mucosal colorectal tumors although its relation with infiltrative activity was unclear in invasive CRC. It was apparent that metachronous hematogenous cancer metastasis might take place even in cases with low proliferative activity.

Acetaminophen-induced inhibition of Fas receptor-mediated liver cell apoptosis: mitochondrial dysfunction versus glutathione depletion.

We reported previously that acetaminophen overdose interrupts the signaling pathway of Fas receptor-mediated apoptosis. The aim of our study was to investigate the mechanism of this effect. Male C3Heb/FeJ mice received a single dose of acetaminophen (300 mg/kg ip) and/or anti-Fas antibody Jo-2 (0.6 mg/kg iv). Some animals were treated with allopurinol (100 mg/kg po) 18 and 1 h before acetaminophen injection. After 90 min of Jo treatment, there was processing of procaspase-3 and a significant increase in liver caspase-3 activity, which is consistent with apoptotic cell death. Treatment with acetaminophen 2.5 h before Jo inhibited the increase in hepatic caspase-3 activity by preventing the processing of the proenzyme. When administered alone, acetaminophen did not induce caspase-3 activation but caused significant liver injury. Acetaminophen treatment alone caused mitochondrial cytochrome c release, depletion of the hepatic ATP content by 55%, and a 10-fold increase in mitochondrial glutathione disulfide levels. Pretreatment with allopurinol prevented the mitochondrial oxidant stress and liver injury due to acetaminophen toxicity but had no effect on Jo-mediated apoptosis. Allopurinol did not affect the initial glutathione depletion after acetaminophen. However, allopurinol restored the sensitivity of hepatocytes to Fas receptor signaling in acetaminophen-treated animals. Histochemical evaluation of DNA fragmentation with the TUNEL assay showed that acetaminophen eliminated Fas receptor-mediated apoptosis in all hepatocytes not just in the damaged cells of the centrilobular area. Our data suggest that acetaminophen-induced mitochondrial dysfunction and not the initial glutathione depletion is responsible for the interruption of Fas receptor-mediated apoptotic signaling in hepatocytes.

Anti-dsDNA antibody up-regulates interleukin 6, but not cyclo-oxygenase, gene expression in glomerular mesangial cells: a marker of immune-mediated renal damage?

OBJECTIVE AND DESIGN: To determine whether anti-double stranded DNA antibody (anti-dsDNA) can affect the synthesis of eicosanoids and cytokines in rat glomerular mesangial cells (RMC). MATERIALS OR SUBJECTS: Glomerular mesangial cells were isolated and subcultured from Sprague-Dawley rats. Monoclonal anti-dsDNA (12B3 clone) was derived from autoimmune MRL-lpr/lpr mouse by hybridoma technology. METHODS: The mRNA expression of cyclo-oxygenase type 1 (COX-1), type 2 (COX-2), Th1 (IL-2 and IFN-gamma)/Th2 (IL-4 and IL-10) and proinflammatory (IL-6 and TNF-alpha) and anti-inflammatory (TGF-beta) cytokines of RMC +/- anti-dsDNA was detected by RT-PCR. The PGE2 production by RMC +/- anti-dsDNA was measured by ELISA. The statistical significance was assessed by non-parametric Wilcoxon signed rank test. RESULTS: We found RMC spontaneously expressed COX-1, but not COX-2. The incubation of RMC with anti-dsDNA (50 ng/ml) did not affect COX expression and PGE2 production by RMC. RMC also spontaneously expressed IL-6, TNF-alpha and TGF-beta mRNA. However, only IL-6 was up-regulated by anti-dsDNA. CONCLUSIONS: Increased IL-6 expression in RMC may become a marker of anti-dsDNA-mediated immune damage of mesangial cells.

'LE cells' result from phagocytosis of apoptotic bodies induced by antinuclear antibodies.

Lupus erythematosus (LE) cells are believed to represent phagocytosis by granulocytes of cell nuclei whose DNA has been 'depolymerized' and opsonized by serum factors, most likely antinuclear antibodies and C3b. Since it is known that certain antinuclear antibodies are capable of inducing apoptosis after intracellular penetration; and that the resulting apoptotic bodies can be ingested by non-professional phagocytes, we decided to investigate the possibility that LE cells could result from the phagocytosis of apoptotic bodies induced by antinuclear antibodies. We demonstrate herein, through different methodological approaches, that the ingested material within LE cells corresponds to apoptotic bodies, and that the LE cell phenomenon can be reproduced, in the absence of other serum factors, by penetrating murine monoclonal anti DNA antibodies.

Some Bence-Jones proteins enter cultured renal tubular cells, reach nuclei and induce cell death.

Eighteen monoclonal Bence-Jones proteins (BJPs) were examined for their effects on cultured LLC-PK1 (porcine kidney proximal tubule) cells as well as for their amidase and DNase activities. Five proteins were found to enter the cell and to gain access to the nucleus without degradation of epitopes. Intranuclear BJPs ultimately induced DNA fragmentation and cell death. BJPs with relatively high amidase activity were cytotoxic. On the other hand, three of four BJPs with DNase activity had a cytocidal effect on cultured cells; the remaining BJP, which had a relatively high DNase activity but a very low amidase activity, failed to enter the cell and was not cytotoxic in vitro. These results suggest that catalytic and cytotoxic activities of some BJPs may make a significant contribution, in a substantial proportion of myeloma patients, to the development and/or deterioration of the disease.

Penetrating anti-DNA monoclonal antibodies induce activation of human peripheral blood mononuclear cells.

Different studies have shown that some autoantibodies are able to penetrate into living cells and that this phenomenon has functional consequences, including apoptosis. We have explored the effect of anti-DNA antibodies (Ab) on the in vitro activation of peripheral blood mononuclear cells (PBMNC) and found that a human polyclonal anti-DNA, IgG, which efficiently penetrated living cells, was able to induce the expression of different cell activation antigens in vitro such as CD69, CD71 or CD98 by PBMNC from normal individuals. However, the cell activation phenotype induced by anti-DNA Ab was considered anomalous since the expression of some activation antigens was not up-regulated, and others showed aberrant behaviour (such as down-regulation of ICAM-1 expression). Similar results were obtained using different murine anti-DNA monoclonal antibodies (mAb). In addition, mAb that showed an efficient ability to penetrate living cells tended to have a greater effect on PBMNC activation. Anti-DNA Ab were also able to induce a noticeable expression of CD95/Fas. These data indicate that penetrating anti-DNA Ab are able to induce an anomalous activation state in vitro in a significant fraction of PBMNC. We believe this effect may occur in vivoand could have an important function in the pathogenesis of the immune dysregulation seen in SLE.

Nucleosome-releasing treatment makes surviving tumor cells better targets for nucleosome-specific anticancer antibodies.

Monoclonal antibody (MoAb) 2C5, a nucleosome-specific antinuclear autoantibody (ANA) from the repertoire of aged mice, was recently reported to recognize the surface of various tumor cells but not normal cells. Surface-bound nucleosomes (NSs) were previously proven to be MoAb 2C5's target on the outer membrane of tumor cells. Furthermore, MoAb 2C5 was found to have a strong antitumor effect during the early stages of tumor development. In an attempt to further increase antitumor effect of nucleosome-specific tumorocidal monoclonal antibody against established tumors, we investigated a possible way to enhance antibody association with tumor cells. Evidence is presented here demonstrating that the in vitro treatment of tumor cells (S49 T lymphoma) resulting in a partial cell death and massive liberation of intact NSs from dead tumor cells into the culture medium was accompanied by a 50-fold increase of MoAb 2C5 binding to the surface of surviving tumor cells. Massive NS release was observed in the case of S49 T-cell treatment with dexamethasone and vincristine. However, a partial cell killing that was not accompanied with NS release (EL4 lymphoma treatment with doxorubicin) did not result in the enhanced binding of MoAb 2C5 to the surface of surviving tumor cells. The use of NS-specific tumorocidal antibodies, such as MoAb 2C5, in combination with another NS release-inducing tumor therapy, should provide an enhanced antibody-tumor binding.