Jan Damoiseaux

We retrospectively evaluated the clinical manifestations of APS in 105 consecutive patients that presented with the suspicion of APS and/or …

We have evaluated a new‐multiplex immunoassay (FIDIS Vasculitis) for simultaneous detection and quantification of anti‐MPO, ‐PR3, and ‐glomerular basement membrane (GBM) antibodies in diagnosis and follow‐up of ANCA‐associated vasculitides (AAV) and Goodpasture's disease. ANCA were determined in sera of (a) 87 consecutive patients with biopsy‐proven pauci‐immune NCGN and 72 controls; (b) 9 patients with Goodpasture's disease; and (c) 60 WG patients and 60 controls, previously used in a multicenter comparison of direct and capture ELISA for PR3‐ANCA. Finally, for prediction of relapses, PR3‐ANCA was measured in samples preceding relapse in 23 PR3‐AAV patients and in 23 matched PR3‐AAV patients without relapse. The relative sensitivity of the FIDIS Vasculitis assay was 97.4% for MPO‐ANCA and 92.3% for PR3‐ANCA; specificity was 100% and 97.2%, respectively. Evaluation of the anti‐GBM antibody detection revealed a sensitivity of 100% and a specificity of 99.6%. The sensitivity for WG of the PR3‐ANCA detection (71.6%) approached the performance of capture ELISA (74%), although at the cost of specificity (96.7% versus 100%). For prediction of relapses a rise of 50% in ANCA level by FIDIS Vasculitis appeared optimal (ROC curve) for prediction of relapses. However, as compared to capture ELISA, both positive (63% versus 76%) and negative (68% versus 72%) predictive values were reduced. In conclusion, simultaneous detection of anti‐MPO, ‐PR3, and ‐GBM antibodies in the multiplex FIDIS Vasculitis assay has excellent performance in terms of diagnosis of patients with AAV or Goodpasture's disease. However, detection of rises in PR3‐ANCA for prediction of relapses gives less optimal results when compared to capture ELISA.

Many patients surviving vasculitis are prone to accelerated atherosclerosis and often have enhanced levels of antibodies to oxidized low-density lipoprotein (oxLDL). To measure anti-oxLDL antibodies, oxidation of LDL is achieved with copper (Cu) or malondialdehyde (MDA). Because, in vivo, LDL may be oxidized with myeloperoxidase (MPO) or its product hypochlorite, we measured anti-hypochlorite LDL antibodies in patients with vasculitis, haemodialysis patients and healthy controls. A newly developed enzyme-linked immunosorbent assay (ELISA) was used to detect antibodies to oxLDL as modified by hypochlorite. Results are compared with data obtained by standard LDL oxidation using MDA–LDL or Cu–LDL as substrate. Results were compared between anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) patients (n = 93), haemodialysis (HD) patients (n = 59) and healthy controls (HC; n = 43). Furthermore, patients with MPO–ANCA-associated vasculitis (n = 47) were compared with patients with proteinase 3 (PR3)–ANCA associated vasculitis (n = 46). Optimal cut-off points were determined by receiver operator characteristic (ROC) curve analysis. Anti-oxLDL antibodies are enhanced in AAV patients (MDA–LDL and hypochlorite–LDL) and in HD patients (hypochlorite–LDL), when compared to HC. Furthermore, patients with MPO–ANCA-associated vasculitis had higher levels of antibodies to hypochlorite–LDL than patients with PR3–ANCA-associated vasculitis. Our newly developed assay, in which hypochlorite–LDL is used as substrate, seems a more sensitive assay than traditional assays to measure oxLDL antibodies. Furthermore, our results suggest that enhanced MPO-mediated LDL oxidation occurs in patients with MPO–ANCA.

Background: Human Heat Shock Protein 60 (hHSP60) has been implicated in autoimmunity through molecular mimicry, based on the high degree of homology with HSP65 of micro-organisms leading to autoimmune recognition of the human protein. Additionally, sequence homology between hHSP60 and myeloperoxidase (MPO) has been described. MPO is a major autoantigen in vasculitis associated with antineutrophil cytoplasmic antibodies (ANCA). We hypothesized that infections may trigger the ANCA response against MPO through hHSP60. Methods: In 86 consecutive patients with ANCA-associated vasculitis (AAV), anti-hHSP60 and anti-mycobacterial HSP65 were measured by ELISA. Patients were compared with 69 healthy controls (HC). Continuous data between groups were compared using Wilcoxon signed rank test and Kruskal-Wallis test with Dunn's post-test when appropriate. Correlations between data were derived using Spearman correlation. Odds ratios and 95% confidence intervals were obtained using Fisher's exact test. Results: At diagnosis, median anti-mHSP65 level was higher in AAV (median [range]: 42.5 [0–500]), and subsequently in MPO-ANCA (44 [7–500]), compared to HC (22 [0–430]). Anti-hHSP60 levels in AAV were not higher compared to HC (18 [0–319] and 18.5 [0–98], respectively). However, in MPO-ANCA anti-hHSP60 levels were increased (32.5 [0–319]) compared to PR3-ANCA (13 [0–79]) and HC. We could not detect cross-reactivity between hHSP60 and MPO-ANCA. There was a correlation between anti-mHSP65 and anti-hHSP60 levels (r = 0.32, P = 0.003) but not between anti-hHSP60 and MPO-ANCA (r = -0.064, P = 0.69). Conclusion: Antibodies against mHSP65 are higher in AAV compared to HC, and anti-hHSP60 antibodies are higher in patients with MPO-ANCA than in patients with PR3-ANCA and HC. Although this finding may be indicative for cross-reactivity between MPO-ANCA and hHSP60, additional assays did not support this hypothesis.

Regulatory T cells seem to represent the resurrection of the old suppressor T cells. Although of a different phenotype, regulatory T cells are able to suppress many T cell mediated immune responses. While most basic knowledge about these cells is derived from animal studies, the recent identification of these cells in humans has further attributed to their characterisation by in vitro analysis. Results obtained have led to broad speculations about therapeutic potential by interference with these regulatory T cells. This review is an introduction to the world of regulatory T cells and contains an historical overview with respect to the identification and characterisation of these T cells. A distinction is made between naturally occurring regulatory T cells (nT(reg)), which require cell-cell contact for suppression, and inducible regulatory T cells (iT(reg)), which predominantly mediate suppression via cytokine dependent pathways. Although only limited studies on regulatory T cells in human disease are available today, the possible clinical applications are discussed in light of the other side of the coin, i.e. the danger of interfering with homeostatic mechanisms in the immune system.

Anopheles stephensi mosquitoes were infected with the chloroquine sensitive NF54 isolate of P falciparum at the insectary, as previously described.⁵ Sets of female mosquitoes were allowed to feed on the forearms for 10 minutes. Subsequent dissection was performed to confirm the presence of sporozoites in the mosquito salivary glands. If not present, the feed was repeated until successful. Volunteers were carefully monitored by assessing blood films twice daily. Upon microscopic detection of parasites, volunteers were immediately treated with a standard curative regimen of chloroquine.

Abstract: We have evaluated the performance of a novel line‐blot immunoassay (LIA; Mikrogen) and compared results with those obtained by CIE (in‐house), ELISA (Pharmacia Diagnostics), and FEIA (Pharmacia Diagnostics). Sera from systemic lupus erythematosus (SLE) patients (n= 123), systemic sclerosis patients (n= 25), and healthy controls (n= 40) were analyzed for the presence of antibodies to RNP, Sm, SSA, SSB, CENP‐B, Scl‐70, and Jo‐1. Reading of LIA results, as compared with a cutoff control, was performed by automatic analysis of the test strips. Because LIA enables recognition of separate subunits of RNP (68, A, and C), Sm (B and D), and SSA (52 and 60), at least two of the RNP antigens and either one of the Sm or SSA antigens should be detected for considering the test RNP, Sm, or SSA‐positive, respectively. LIA had the highest sensitivity in patients with autoimmune connective tissue diseases: 131 specificities (not PO, PCNA, or histones), as compared with ELISA (121), FEIA (119), and CIE (80). However, LIA revealed three positive reactions in healthy controls; other assays were completely negative. LIA is better than CIE, but similar to ELISA and FEIA, in terms of detecting systemic sclerosis‐associated antibodies (CENP‐B and Scl‐70). Furthermore, LIA had the highest sensitivity (17.9%) for the SLE‐specific anti‐Sm antibodies, as compared with ELISA (11.4%), CIE (8.1%), and FEIA (5.7%). Finally, anti‐SSA antibodies were far more prevalent by LIA in the systemic sclerosis samples because of anti‐SSA52 reactivity. The clinical relevance of the latter finding remains to be determined. In conclusion, LIA is suitable for routine evaluation of autoantibodies to extractable nuclear antigens.

Abstract: Anticardiolipin antibodies (aCLAs) and antibodies to oxidized‐low density lipoproteins (oxLDL) are associated with two distinct diseases: the antiphospholipid syndrome and atherosclerosis. Because both diseases may be apparent in patients with systemic lupus erythematosus (SLE), it is important to establish the relationship between these two types of antibodies. In the present study, we examined whether sera containing IgM and/or IgG aCLAs also react with LDL that has been oxidized by conjugation with malondialdehyde (MDA‐LDL) or by incubation with copper ions (Cu‐LDL). Results revealed a clear correlation between IgM aCLAs and IgM anti‐MDA‐LDL antibodies, and a weak correlation between IgG aCLAs and IgG anti‐Cu‐LDL antibodies. Cross‐reactivity between both antibodies seemed to be limited. Because aCLAs are heterogeneous, only a minor subset of these antibodies may cross‐react with oxLDL. Therefore, identification of both antibodies may be relevant for determination of the prognosis of accelerated atherosclerosis in SLE patients.

In this study we have evaluated a new, fully automated fluorescent-enzyme immuno-assay (FEIA) for detection and quantification of anti-PR3 and anti-MPO ANCA in diagnosis and follow-up of ANCA-associated small vessel vasculitis (AAV). PR3- and MPO-ANCA were determined by FEIA technology in (1) sera of 87 consecutive patients with biopsy-proven, pauci-immune necrotizing crescentic glomerulonephritis (NCGN) and 72 controls; (2) 120 sera (60 patients with Wegener’s granulomatosis and 60 controls) that were previously used in a multicentre comparison of direct and capture ELISAs for PR3-ANCA; (3) in samples preceding relapse in 23 PR3-AAV patients with and 23 matched PR3-AAV patients without relapse for prediction of relapses. PR3- and/or MPO-ANCA detection in pauci-immune NCGN by FEIA revealed an overall sensitivity of 82.8%. The FEIA specificity was 96% and 100% for PR3- and MPO-ANCA, respectively. The overall sensitivity of MPO- and PR3-ANCA could be increased to 88.5% by lowering the cut-off values without affecting the specificity (ROC-curve analysis), which is similar to a multistep ANCA procedure that combines indirect immunofluorescence with direct and capture ELISAs. The sensitivity for Wegener’s granulomatosis (WG) of the PR3-ANCA FEIA (60%) was more comparable to direct ELISAs (64%) than to capture ELISAs (74%). A rise of 100% in ANCA level as measured by FEIA appeared optimal (ROC-curve) for prediction of relapses and such a rise was observed in 26 patients. In 18 of these 26 patients the rise was followed by a relapse (PPV 69%), whereas in 15 of the 20 patients without a rise no relapse was observed (NPV 75%). In conclusion, detection of PR3- and MPO-ANCA by FEIA has excellent performance in terms of diagnosis of AAV patients. Furthermore, detection of rises in PR3-ANCA by FEIA for prediction of relapses gives results comparable to other techniques.