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Biomedical subjects

J B Marriott

Publications and source records attributed to J B Marriott.

At least 19 recordsLinked to original sources
PubMed2002

Novel thalidomide analogues display anti-angiogenic activity independently of immunomodulatory effects.

The anti-tumour effects of thalidomide have been associated with its anti-angiogenic properties. Second generation thalidomide analogues are distinct compounds with enhanced therapeutic potential. Although these compounds are beginning to enter trials for the treatment of cancer there is very little information regarding the anti-angiogenic activity of these clinically relevant compounds. Furthermore, it is not known how the various immunomodulatory activities of these compounds relate to anti-angiogenic activity. In this study we assessed the anti-angiogenic activity of compounds from both IMiD and SelCID classes of analogues using a novel in vitro multicellular human assay system and the established rat aorta assay. Our results show that both the IMiDs and SelCIDs tested are significantly more potent than thalidomide. The anti-angiogenic potency of the analogues was not related to inhibition of endothelial cell proliferation, nor their TNF-alpha/PDE type 4 inhibitory properties. However, anti-migratory effects in vitro and inhibition of tumour growth in vivo was observed with the analogue IMiD-1 (clinically known as REVIMID). Our results show that anti-angiogenic activity spans both currently defined classes of thalidomide analogue and is not related to their previously described immunomodulatory properties. Identification of the differential effects of these compounds will enable targeting of such compounds into the appropriate clinical setting.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2002

Thalidomide and its analogues have distinct and opposing effects on TNF-alpha and TNFR2 during co-stimulation of both CD4(+) and CD8(+) T cells.

Thalidomide (Thd) is clinically useful in a number of conditions where its efficacy is probably related to its anti-TNF-alpha activity. More recently, Thd has also been shown to co-stimulate T cells and second generation co-stimulatory (IMiD trade mark ) analogues are currently being assessed in the treatment of cancer patients. However, in contrast to their known suppressive effects during inflammatory stimuli, the effects of Thd/IMiDs on TNF-alpha and TNF receptors (TNFRs) during T cell co-stimulation are not known. We sought to determine the effect of Thd, two clinically relevant IMiDs (CC-4047, ACTIMID trade mark and CC-5013, REVIMID trade mark ) and a non-stimulatory SelCID analogue (CC-3052) on TNF-alpha production and on the expression and shedding of TNFRs during co-stimulation. We found that co-stimulation of PBMC with Thd/IMiDs, but not CC-3052, prevented alphaCD3-induced T cell surface expression of TNFR2 and thereby reduced soluble TNFR2 (sTNFR2) levels. However, there was no effect on total (surface/intracellular) TNFR2 protein expression, suggesting inhibition of trafficking to the cell membrane. The extent of co-stimulation by Thd/IMiDs (assessed by CD69/CD25 expression and IL-2/sIL-2Ralpha production) was similar for CD4+ and CD8+ T lymphocytes and correlated with TNFR2 inhibition. Co-stimulation, but not the early inhibitory effect on TNFR2, was IL-2-dependent and led to increased TNF-alpha production by both CD4+ and CD8+ T lymphocytes. The clinical relevance of this observation was confirmed by the elevation of serum TNF-alpha during REVIMID trade mark treatment of patients with advanced cancer. Together, these results suggest a possible role for TNF-mediated events during co-stimulation and contrast with the TNF inhibitory effects of Thd and its analogues during inflammatory stimuli.

Adjuvants, Immunologic↗
PubMed2001

Inhibition of p38 MAP kinase during cellular activation results in IFN-gamma-dependent augmentation of IL-12 production by human monocytes/macrophages.

Interleukin-12 (IL-12) is a key immunomodulatory cytokine produced by antigen-presenting cells that promotes cellular immunity and enables the generation of protective immunity against intracellular pathogens and tumours. Therefore, modulation of IL-12 activity is a primary immunotherapeutic goal. However, little is known about its regulation. Signalling via p38 MAPK has been implicated in the control of inflammatory responses and is therefore a potential therapeutic target. We have used the highly selective p38 MAPK inhibitor (SB203580) to examine the effect of this pathway on the production of IL-12. Surprisingly, we found that SB203580 strongly up-regulated LPS induced IL-12p40 at the protein (intracellular and secreted) and mRNA levels in PBMC cultures. The effect on IL-12 was apparent using both T cell-independent and T cell-dependent stimuli but not in unstimulated cultures, indicating that activation signals are required. Furthermore, the production of IFN-gamma by T cells is crucial as production was not increased in LPS-stimulated, purified adherent monocytes/macrophages without the addition of exogenous IFN-gamma. These results provide evidence that p38 MAPK has an unexpected suppressive effect on IL-12p40 gene transcription, and suggests interplay between p38 MAPK- and IFN-gamma -mediated signals in the regulation of IL-12 production by monocytes/macrophages. Furthermore, the importance of IL-12 as a key immunoregulatory cytokine suggests that the clinical application of pyrinidyl imidazole inhibitors, such as SB203580, may need to be reassessed.

Antigen-Presenting Cells↗
PubMed2001

Immunotherapeutic and antitumour potential of thalidomide analogues.

The immunomodulatory drug thalidomide has been shown to be clinically useful in a number of conditions including various immunological disorders and cancers. Clinical activity in vivo is attributed to the wide ranging immunological and non-immunological properties possessed by this drug; these include anti-TNF-alpha, T-cell co-stimulatory, anti-angiogenic activities and also direct antitumour activity. Recently, the design of compounds based on the thalidomide structure has led to the synthesis of analogues with greatly enhanced immunological activity and with similarly decreased toxicity. These derivatives fail into at least two categories; selective cytokine inhibitory drugs (SelCID), which are phosphodiesterase Type 4 (PDE4) inhibitors and immunomodulatory drugs (IMiD), similar to thalidomide which act via unknown mechanism(s). These compounds are in the process of being characterised in laboratory studies and are also now being assessed in Phase I and Phase I/II clinical studies. In this review we will highlight the properties of these two novel classes of compound in terms of their effects on both immunological and non-immunological systems in vitro. We will also describe how these studies are enabling the characterisation and development of these compounds into clinically relevant drugs in widely varying diseases. To this end we will describe the various clinical studies of lead compounds that are in progress and speculate as to the potential and future development of these exciting compounds.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2000

The thalidomide analogue CC-3052 inhibits HIV-1 and tumour necrosis factor-alpha (TNF-alpha) expression in acutely and chronically infected cells in vitro.

We investigated the in vitro effect of the water-soluble, highly stable thalidomide analogue CC-3052 on HIV-1 expression and TNF-alpha production in latently infected promonocytic U1 cells, acutely infected T cells and monocyte-derived human macrophages (MDM), and in mitogen-stimulated ex vivo cultures from patients with primary acute HIV-1 infection. HIV-1 expression was assessed by Northern blot analysis of RNAs, and ELISA for p24 antigen release and reverse transcriptase (RT) activity. TNF-alpha expression was evaluated by RT-polymerase chain reaction (PCR)-ELISA for mRNA and ELISA for protein secretion. We demonstrated that CC-3052 is able to inhibit HIV-1 expression, as evaluated by mRNA, p24 release and RT activity, in phorbol myristate acetate (PMA)- and cytokine-stimulated U1 cells. Furthermore, CC-3052 inhibited HIV-1 expression, as evaluated by p24 and RT activity, in acutely infected MDM and T cells. As far as TNF-alpha is concerned, CC-3052 significantly reduced TNF-alpha mRNA and protein secretion in PMA-stimulated U937 and U1 cells, and in PMA-stimulated uninfected and acutely infected MDM. Consistently, the addition of CC-3052 reduced TNF-alpha production in phytohaemagglutinin (PHA) and lipopolysaccharide (LPS)-stimulated whole blood cultures from patients during the primary acute phase of HIV-1 infection. Since TNF-alpha is among the most potent enhancers of HIV-1 expression, the effect of CC-3052 on TNF-alpha may account for its inhibitory activity on HIV-1 expression. Given the well documented immunopathological role of TNF-alpha and its correlation with viral load, advanced disease and poor prognosis, CC-3052 could be an interesting drug for the design of therapeutic strategies in association with anti-retroviral agents.

Anti-HIV Agents↗
PubMed2000

Reduction in cytokine production in colorectal cancer patients: association with stage and reversal by resection.

The aim of this study was to assess monocyte/macrophage function, as defined by lipopolysaccharide (LPS)-induced production of tumour necrosis factor (TNF)-alpha, interleukin (IL)-10 and interferon (IFN)-gamma by stimulated whole blood cultures in patients with colorectal carcinoma before and after surgical resection. Forty colorectal cancer patients prior to surgery and 31 healthy controls were studied. Heparinized venous blood was taken from colorectal cancer patients prior to surgery and from healthy controls. Serial samples were obtained at least 3-6 weeks post-operatively. Blood was stimulated with LPS for 24 h and supernatants were assayed for TNF-alpha, IFN-gamma and IL-10 by enzyme-linked immunosorbent assay. LPS-induced production of TNF-alpha and of IFN-gamma was reduced in patients with colorectal carcinoma compared to controls (TNF-alpha, 11,269 pg/ml(-1) ¿12,598¿; IFN-gamma, 0.00 pg/ml(-1) ¿226¿; median ¿IQR¿) (TNF-alpha, 20,576 pg/m(-1) ¿11,637¿, P < 0.0001; IFN-gamma, 1,048 ¿2,428¿, P = 0.0051, Mann-Whitney U-test). Production in patients after surgery had increased (TNF-alpha: 17,620 pg/ml(-1) ¿7,986¿; IFN-gamma. 410 pg/ml(-1) ¿2,696¿; mean ¿s.d.¿) and were no longer significantly reduced when compared to controls (TNF-alpha, P = 0.28; IFN-gamma, P = 0.76). Production of TNF-alpha and IFN-gamma prior to surgery were reduced to a greater extent in patients with Dukes' stage C tumours compared to those with Dukes' stage A and B stage. There was no difference in IL-10 production between any group. Monocytes/macrophages from patients with colorectal carcinoma are refractory to LPS stimulation as reflected by reduction in TNF-alpha and IFN-gamma production and this is more pronounced in patients with advanced stage tumours. This suppression is not mediated by IL-10 and disappears following surgical resection of the tumour. This provides evidence for tumour induced suppression of immune function in patients with colorectal cancer and identifies a potential therapeutic avenue.

Aged↗
PubMed1999

The conserved carboxy terminal region of HIV-1 gp120 is recognized by seronegative HIV-exposed people.

OBJECTIVE: To screen HIV-positive, long-term exposed seronegative and low-risk individuals for the presence of antibodies against regions of HIV-1 gp120 that share some degree of homology with HLA. METHODS: Sera were obtained from 63 HIV-1-infected subjects [52 Centers for Disease Control and Prevention (CDC) stage 2 and 11 stages 3/4], 32 HIV-exposed uninfected (HEU) subjects and from 24 low-risk HIV-1 seronegative individuals. They were tested by a peptide-based enzyme-linked immunosorbent assay (ELISA) for reactivity against peptides derived from the HIV-1 gp120 C-terminal region that contain regions of MHC sequence/structural similarity. Ten randomly selected sera from each group were also screened for anti-class I antibodies. RESULTS: Thirty per cent of the long-term HIV-1-exposed seronegative individuals had antibodies against the conserved C-terminal region (C5) of HIV-1 gp120. However, sera from HEU individuals showed no reactivity against other peptides derived from the C2 region of gp120, also an HLA homologous region. Anti-C terminal gp120 antibodies were mainly of IgM subclass, although IgG-specific antibodies were also present. In addition, 70% of HEU individuals had antibodies to HLA class I molecules compared with 15% of HIV-positive patients (restricted to only those HIV-positive patients with anti C-terminal antibodies). CONCLUSION: Our results suggest that antibody responses against the C-terminal region of HIV gp120 and HLA class I may represent markers of apparent natural protection against HIV-1 infection.

AIDS Serodiagnosis↗
PubMed1999

The role of HIV gp120 in the disruption of the immune system.

The existence of HIV positive individuals who do not appear to progress to disease, or do so only very slowly (LTNPs), strongly suggest that factors other than virus pathogenicity determine disease. The occurence of HIV infected chimpanzees that remain disease free and other African SIV infected primates where disease is apparently species specific underscores the importance of host factors [1,2]. We have examined the immune response of LTNP patients using a variety of techniques including intracellular cytokine FACscan, anchor PCR analysis of the T cell receptor and HLA typing of class II genes by DNA sequencing. Our results to date confirm that the development of disease is consistent with activation of a susceptible immune system, and that this could be due to the fact that HLA-like sequences of HIV may 'allo' activate the host immune response. In order to test this hypothesis further we have examined whether gp120 itself can bind and present specific peptides which may be capable of eliciting 'allo' activation responses in particular hosts.

Antigen Presentation↗
PubMed1998

CC-3052: a water-soluble analog of thalidomide and potent inhibitor of activation-induced TNF-alpha production.

The immunomodulatory drug thalidomide has been shown to be clinically useful in a number of situations due to its ability to inhibit TNF-alpha synthesis. However, its use is restricted by potentially serious side effects, including teratogenicity and neuorotoxicity; furthermore, insolubility may present problems in terms of systemic bioavailability. Recently, structural modifications of thalidomide have been designed enabling greatly enhanced anti-TNF-alpha activity in LPS-treated mice. In contrast to thalidomide (LPS-induced TNF-alpha IC50 approximately 200 microM in DMSO) and other analogs tested, one of these compounds, CC-3052 (IC50 approximately 1 microM in water), is water soluble. Furthermore, this analog exhibits increased stability in human plasma (t(1/2) approximately 17.5 vs 1.5 h for thalidomide) and appears to be nontoxic, nonmutagenic, and nonteratogenic. At pharmacologically active levels, cellular proliferation and LPS-induced IL-6 mRNA and IL-12p40 mRNA (as well as IL-1beta and IL-6 protein levels) in whole blood cultures were not affected; apparent inhibition of NK activity by CC-3052 was reversed upon addition of exogenous rTNF-alpha. In addition, IL-10 mRNA and protein levels were increased. These properties are consistent with results indicating inhibition of phosphodiesterase type IV activity by CC-3052. Furthermore, CC-3052 did not increase the degradation rate of macrophage TNF-alpha transcripts nor inhibit LPS-induced primary macrophage NF-kappaB activation. Taken together, the potency of selective TNF-alpha inhibition, water solubility, and increased plasma stability make CC-3052 an excellent candidate for further development and clinical evaluation for the treatment of TNF-alpha-mediated disease.

Adjuvants, Immunologic↗
PubMed1998

Abnormal intracellular IL-2 and interferon-gamma (IFN-gamma) production as HIV-1-assocated markers of immune dysfunction.

We used three-colour cytometry to analyse intracellular cytokine production in activated whole blood cultures derived from patients with HIV-1 infection. We assessed mitogen-induced IL-2, IL-4 and IFN-gamma production from T cells as possible markers of immune dysfunction. The percentages of T cells staining for IL-2 were significantly reduced in stimulated cultures from HIV+ individuals relative to normal controls (P<0.0001); this reduction was observed in both the CD4+ and the CD8+ subsets. IL-2 production was significantly reduced in CD4+ T cells from HIV+ individuals clinically classified as symptomatics compared with HIV+ asymptomatics (P<0.001); in addition, production of IL-2 inversely correlated with viral load (r2=0.832). On the other hand, HIV+ individuals showed significantly more T cells staining positive for IFN-gamma (P<0.0001); subset analysis identified these T cells as CD8+. Increased IFN-gamma production in the CD8+ T cell subset of HIV+ individuals correlated neither with clinical status nor with plasma viral load. IL-4 staining in activated T cells was low (<5%) and no differences were observed between HIV+ and control groups. Three-colour FACS analysis of whole blood provides a sensitive, rapid and relatively easy means to detect cytokine profiles within T cell subpopulations. Only small volumes of blood are required (0.5 ml), since there is no need for cell isolation, making it more practical than ELISA or reverse transcriptase-polymerase chain reaction (RT-PCR) for the analysis of immune function in HIV+ individuals. This technique could therefore play a role in mapping the dynamics and extent of immune recovery in AIDS patients undergoing triple combination therapy.

Adult↗
PubMed1998

Tumour necrosis factor (TNF) and TNF-related molecules in HIV-1+ individuals: relationship with in vitro Th1/Th2-type response.

We examined the secretion and expression by peripheral blood mononuclear cells (PBMC) of TNF-alpha and TNF-related molecules with regard to Th1/Th2-type cytokine production. In 76 HIV+ patients at different disease stages and in 25 controls we measured cytokine (TNF-alpha/beta, interferon-gamma (IFN-gamma), IL-2, IL-4, IL-10), and activation marker secretion (sCD4, sCD8, sCD30) in phytohaemagglutinin (PHA)-stimulated and unstimulated PBMC cultures by ELISA, and membrane-bound TNF-alpha and CD30 expression by flow cytometry. We found an expansion of the TNF system in HIV+ individuals, that positively correlated with TNF-alpha, IFN-gamma and sCD8, probably representing activation of the cytotoxic compartment. In advanced disease these correlations disappeared, and TNF-alpha and TNF-related molecules positively correlated with IL-10. Our results are in line with the hypothesis that an expanded TNF system is immunopathological in conjunction with Th2-type immunity in the advanced stage of disease and with the inexorable progression to disease seen when both IL-10 and TNF-alpha are elevated.

Adult↗
PubMed1997

A double-blind placebo-controlled phase II trial of thalidomide in asymptomatic HIV-positive patients: clinical tolerance and effect on activation markers and cytokines.

A randomized double-blind, placebo-controlled study was performed to determine the safety, efficacy, and effect of thalidomide on a variety of immunological and biochemical parameters in asymptomatic human immunodeficiency virus (HIV)-positive patients. Nineteen male patients with elevated markers of immune activation and CD4 cell counts above 400/mm3 were randomized to either placebo or thalidomide at 100 mg/day for 24 weeks. However, only 3 (of 10) patients receiving thalidomide completed all 24 weeks compared to 6 (of 9) patients receiving placebo. This was mainly due to fatigue (somnolence is a recognized side effect), although this was also seen to a lesser extent in the placebo group and so may not be drug attributable. No significant changes in CD4/CD8 count, activation markers, TNF-alpha, or TNFR1 were observed. However, a nonsignificant trend toward inhibition of mitogen-induced TNF-alpha production was observed in the thalidomide arm. The lack of systemic effect and the lower tolerance of thalidomide (at this dose) in asymptomatic patients highlights the need for pharmacokinetic analysis to address possible absorption problems and the need for more potent and less toxic TNF-alpha inhibitors to be developed for use in this type of study.

Adult↗
PubMed1997

TNF-alpha antagonists: monoclonal antibodies, soluble receptors, thalidomide and other novel approaches.

Tumour necrosis factor-alpha (TNF-alpha) is a pleiotropic molecule produced in response to a variety of stimuli during normal host defence. At low levels, TNF-alpha confers protection against infectious agents, tumours and tissue damage, and plays a role in the development of humoral immunity. However, overproduction of TNF-alpha has been implicated in the pathogenesis of a wide variety of conditions, including autoimmunity, malignancy, inflammatory and immunopathological diseases. Furthermore, TNF-alpha is a key regulator of other pro-inflammatory cytokines; infiltrating mononuclear cells that produce excessive amounts of TNF-alpha at sites of inflammation are, therefore, primary targets for therapeutic intervention. Traditional anti-inflammatory drugs, such as cyclosporin, have widespread immunosuppressive effects and are now being replaced by more specific anti-TNF-alpha compounds. In this report, work presented at the recent Cambridge Symposia meeting on TNF-alpha antagonists in Santa Fe, New Mexico, will be highlighted and discussed.

Journal Article↗
PubMed1996

Interleukin-10-induced HIV-1 expression is mediated by induction of both membrane-bound tumour necrosis factor (TNF)-alpha and TNF receptor type 1 in a promonocytic cell line.

OBJECTIVE: To investigate whether the upregulatory effect of interleukin (IL)-10 on HIV expression in a model of latent HIV infection is mediated by induction of endogenous tumour necrosis factor (TNF)-alpha and TNF receptors (TNFR). DESIGN: The latently HIV-infected promonocytic cell line U1 was examined, because in this in vitro model IL-10 has been shown to synergize with multiple cytokines, including TNF-alpha, in enhancing HIV production. METHODS: Membrane-bound TNF-alpha, TNFR-1 and TNFR-2 surface expression were determined by flow cytometry. TNF-alpha mRNA was estimated by competitive polymerase chain reaction (PCR), and TNF-alpha, soluble TNFR-1 and soluble TNFR-2 supernatant content by enzyme-linked immunosorbent assay. HIV-1 expression was quantitated by reverse transcriptase assay and p24 antigen release. RESULTS: We demonstrated that IL-10 induces a time and cell-concentration dependent upregulation of HIV expression in U1 cells. This effect is mediated through the endogenous production of TNF-alpha as demonstrated by blocking experiments with anti-TNF-alpha antibodies and by detection of IL-10-induced increase of TNF-alpha mRNA by competitive PCR. More importantly, IL-10 is able to upregulate membrane-bound TNF-alpha and TNFR-1, along with a consistent increase in the shedding of soluble TNFR-1 without inducing detectable TNF-alpha secretion. CONCLUSIONS: IL-10 activates HIV expression through the membrane-bound TNF-alpha/TNFR-1 pathway, suggesting an amplification mechanism of HIV expression that might occur during cell-to-cell interaction. This positive regulatory effect of IL-10 in an in vitro model of chronic HIV infection is consistent with the inexorable progression of disease seen in advanced patients when both IL-10 and TNF-alpha are elevated.

Antigens, CD↗
PubMed1996

Abnormal cytokine profiles in patients with idiopathic dilated cardiomyopathy and their asymptomatic relatives.

OBJECTIVES: Immunological abnormalities in idiopathic dilated cardiomyopathy (DCM) include an increase in soluble interleukin (IL)-2 receptor, disease specific cardiac autoantibodies, an HLA-DR4 association, and familial aggregation of disease; however, cytokine profiles have not been defined. Serum concentrations of IL-2, IL-4, IL-10, and IL-12 were measured in patients with DCM (WHO criteria), relatives with asymptomatic left ventricular enlargement (LVE), patients with ischaemic heart failure (IHD), and healthy controls. DESIGN: Serum from 20 individuals from each of the four groups was assayed for cytokine concentrations by a commercial enzyme linked immunosorbent assay. RESULTS: IL-2 concentrations were abnormally increased in DCM patients and relatives with LVE. Concentrations of IL-10 were increased in DCM patients. Concentrations of IL-4 and IL-12 were not increased in any of the groups. CONCLUSION: These abnormalities may reflect defective/inappropriate T cell function in patients with DCM and in their relatives with LVE.

Adolescent↗
PubMed1996

Comparison of IL-2- and IL-4-transfected B16-F10 cells with a novel oil-microemulsion adjuvant for B16-F10 whole cell tumour vaccine.

The use of whole cell tumour vaccines in the treatment of malignant melanoma has given mixed results. Cytokine-transfected tumour cells as vaccine have shown efficacy in animal models but need to be compared with other means of enhancing a systemic anti-tumour immune response. A new generation of immunological adjuvants claimed to be more effective than the conventional adjuvants is now available for assessment. We have investigated the action of an oil-microemulsion adjuvant formulation (IDEC antigen formulation (IDEC-AF)) in the B16-F10 murine melanoma model. After standardisation of the whole cell tumour vaccination protocol we showed that mice vaccinated with whole irradiated cells combined with IDEC-AF produced a significant inhibition of tumour growth, following a challenge with live tumour cells, when compared with mice vaccinated with whole cell vaccine alone. IDEC-AF was superior to two conventional adjuvants, namely alum and incomplete Freund's adjuvant and a more reliable response was achieved with the oil-microemulsion adjuvant compared with IL-2-transfected cells. In addition, the adjuvant was comparable in efficacy to IL-4-transfected B16-F10 cells. Given the practical difficulty in using cytokine-transfected tumour cells and the limited therapeutic range of some cytokines, a cheap and easy to deliver adjuvant formulation proved equally or more effective than some of the currently clinically used transfected cytokines.

Alum Compounds↗
PubMed1994

Anti-phospholipid antibodies in the mercuric chloride treated brown Norway rat.

Anti-phospholipid antibodies (aPL), in the form of anti-cardiolipin antibodies (aCL) and/or lupus anticoagulant (LAC), are found in a number of disorders, including systemic lupus erythematosus. Autoimmune aPL are associated with clinical manifestations that may include vascular thrombosis, recurrent fetal loss, thrombocytopenia, livedo reticularis and neurological abnormalities. aPL found in the context of infections such as syphilis are not usually associated with clinical complications. Here we report the presence of aCL in Brown Norway (BN) rats treated with mercuric chloride (HgCl2), which is known to induce a number of other autoantibodies. Some also showed LAC activity as shown by extension of the kaolin clotting test time. The binding of human autoimmune aPL is known to be considerably enhanced by a serum cofactor, beta 2-glycoprotein I; only slight enhancement, and in some cases inhibition, was found with BN rat aPL. These results indicate that aPL can be added to the list of autoantibodies that have been documented in the HgCl2 treated BN rat. The effect of addition of serum co-factor suggests that these are most closely related to human infection-associated (as opposed to autoimmune) aPL.

Animals↗