B and T cell responses induced by interleukin-6.
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Animals↗
Biomedical subjects
F Houssiau
Publications and source records attributed to F Houssiau.
Changes in brain water in systemic lupus erythematosus.
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Adult↗
High 6-thioguanine nucleotide levels and low thiopurine methyltransferase activity in patients with lupus erythematosus treated with azathioprine.
Azathioprine (AZA) is characterized by a high interindividual variability in bioavailability and metabolism. AZA is converted into 6-thioguanine nucleotides (6-TGN) to which the immune modifier activity is attributed. The 6-TGN levels are known to be affected by the activity of the key enzyme, thiopurine methyltransferase (TPMT), which is under genetic dependence. The authors measured a significantly lower TPMT activity in 53 women with systemic lupus erythematosus (SLE) (12.2 +/- 2.4 pmol/h/ml RBC; P < 0.01) when compared with 30 healthy control participants (13.15 +/- 3.1 pmol/h/ml RBC) but not with 28 patients with other dysimmune diseases (non-SLE; 13.0 +/- 3.0 pmol/h/ml RBC; P = 0.10). To evaluate the impact of TPMT activity on the concentrations of AZA metabolites, we measured the TPMT activity and 6-TGN levels in a subgroup of 26 patients in remission and treated with a stable dose of AZA (mean value: 1.9 +/- 0.5 mg/kg/day) for at least six months (n = 13 with SLE and n = 13 with other dysimmune diseases, ie, non-SLE). In such a subgroup, no correlation between 6-TGN levels and TPMT activity was observed. However, patients with SLE presented lower TPMT activity and higher 6-TGN levels (215 +/- 123 versus 140 +/- 75 pmol/8 x 10(8) RBC in non-SLE patients; P < 0.04). It must be noted that transient increase in 6-methylmercaptopurine levels (6-MMP), a putative toxic metabolite (up to 21.7 nmol/8 x 10(8) RBC), was more frequently observed in the non-SLE group (P < 0.01). Even if a relationship was observed between low TPMT activity and 6-TGN levels in SLE, its clinical impact appears to be limited as far as regular hematologic controls are performed.
Azathioprine↗
Anti-neutrophil cytoplasmic antibodies in 566 European patients with systemic lupus erythematosus: prevalence, clinical associations and correlation with other autoantibodies. European Concerted Action on the Immunogenetics of SLE.
OBJECTIVES: To evaluate, in a cohort of 566 patients with systemic lupus erythematosus (SLE) drawn from 11 European centres: (i) the prevalence of ANCAs and their subspecificities in a large series of European SLE patients; (ii) the possible associations of ANCA with the most common clinical manifestations of the disease; and (iii) whether ANCAs correlate with some of the autoantibodies commonly found in SLE. METHODS: ANCA detection was performed by indirect immunofluorescence (IIF), and by ELISA for lactoferrin (LF), myeloperoxydase (MPO), proteinase3 (PR3) and lysozyme (LZ) subspecificities. RESULTS: The prevalence of ANCA was 16.4% (IIF). The prevalence of LF was 14.3%, LZ 4.6%, MPO 9.3%, and PR3 1.7%. Our results show that ANCA is associated with certain clinical manifestations of SLE. In particular, positive correlations were found between IIF ANCA and serositis (p = 0.026), livedo reticularis (p = 0.01), venous thrombosis (p = 0.03) and arthritis (p = 0.04), while anti-LF antibodies were associated with serositis (p = 0.05) and livedo reticularis (p < 10(-3). Nevertheless, multivariate analysis demonstrated that other autoantibodies, such as aCL and SSA/Ro, are more closely correlated than ANCA with some of the aforementioned clinical features. CONCLUSION: Our results demonstrate that ANCA are detectable in SLE sera and that some of them are associated with particular clinical manifestations. Whether ANCA plays a direct pathogenetic role in the vascular damage of SLE or only represents an epiphenomenon or a marker of disease activity remains to be elucidated.
Adolescent↗
Association of 16/6 and SA1 anti-DNA idiotypes with anticardiolipin antibodies and clinical manifestations in a large cohort of SLE patients. European Concerted Action on the Immunogenetics of SLE.
OBJECTIVE: The SA1 and 16/6 idiotypes can be found in some patients with systemic lupus erythematosus (SLE) or anti-phospholipid syndrome (APS). The aim of this study was to ascertain the prevalence of these idiotypes in a large cohort of SLE patients, and to determine whether their presence is correlated with the anticardiolipin (aCL) and anti-dsDNA antibodies or with the clinical manifestations of SLE. METHODS: 492 SLE patients were evaluated for clinical manifestations of SLE and were assigned a disease severity score. ds-DNA autoantibodies, aCL autoantibodies of the IgM, IgG and IgA isotypes, and SA1 and 16/6 idiotypes were also determined in these patients. RESULTS: The prevalence of the SA1 and 16/6 idiotypes in the 492 SLE patients was found to be 11% and 5.1%, respectively, and these idiotypes were significantly more prevalent in the patients who had aCL antibodies of either the IgG, IgM or IgA isotypes. Moreover, while the 16/6 idiotype was not associated with the clinical manifestation of either SLE or APS, the SA1 idiotype was found significantly more frequently in patients who had vascular events Raynaud's phenomenon or hemolytic anemia (p = 0.016, 0.01, 0.01, respectively). CONCLUSION: SLE patients with the SA1 idiotype may run a higher risk of developing vascular events, Raynaud's phenomenon or hemolytic anemia. These clinical manifestations can be attributed to both SLE and secondary APS when aCL autoantibodies are also found. These results indicate that the possible pathogenicity of certain idiotypes in SLE cannot be excluded.
Adolescent↗