Tetsuki Amano

Levels of interleukin‐18 and its binding inhibitors in the blood circulation of patients with adult‐onset Still's disease

OBJECTIVE Interleukin-18 (IL-18) is a proinflammatory cytokine that is involved in immunologically mediated tissue damage, but its bioactivity is regulated in vivo by its soluble decoy receptor, IL-18 binding protein (IL-18BP). This study was undertaken to determine levels of IL-18 and IL-18 binding inhibition in the blood of patients with adult-onset Stills disease (ASD). METHODS Serum concentrations of IL-18 in ASD patients were compared by enzyme-linked immunosorbent assay (ELISA) with those in patients with other systemic rheumatic diseases and healthy controls. The biologically active mature protein of IL-18 was detected by Western blot analysis with anti-IL-18 antibody and its induction of interferon-gamma (IFNgamma) secretion from IL-18-responding human myelomonocytic KG-1 cells. The inhibitory activity on IL-18 binding to its receptor was determined by 125I-IL-18 binding inhibition assay using the Chinese hamster ovary cell line transfected with a murine IL-18 receptor (CHO-K1/mIL-18R). RESULTS Concentrations of serum IL-18 were extremely elevated in patients with active ASD compared with those in patients with rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, polymyositis/dermatomyositis, Sjogrens syndrome, or healthy individuals. Levels of IL-18 were found to correlate with serum ferritin values and disease severity in ASD. Western blot analysis revealed that serum samples from patients with active ASD contained an 18-kd polypeptide of IL-18, corresponding in size to the mature form. Accordingly, the samples were able to induce IFNgamma secretion from KG-1 cells, which was largely abolished by neutralizing anti-IL-18 antibody. However, the level of IL-18 bioactivity was more than 10-fold weaker than the concentration of IL-18 protein measured by ELISA. Serum samples from patients with active ASD showed an inhibitory effect on the binding of 125I-IL-18 to CHO-K1/mIL-18R cells, and this activity was associated with elevation of IL-18. CONCLUSION These data indicate that systemic overproduction of IL-18 may be closely related to the pathogenesis of ASD, despite the restriction on its inflammatory activity by IL-18 binding inhibitors such as IL-18BP. The disease activity appears to be determined on the basis of the relative levels of IL-18 and its specific inhibitors.

HAEMOPHAGOCYTIC SYNDROME TREATED WITH CYCLOSPORIN A: A T CELL DISORDER?

abnormal cells were CD4 + , in one case CD8 + and in four cases could be detected in both cellular subsets. Specific antibodies against CMV, HBV, EBV, HV and HTLV-I were not detected in any of these cases. The presence of atypical lymphoid cells (multilobated nuclei) can have several causes. In the case we report here, the coincidental occurrence of an adult T-cell leukaemia/ lymphoma can be ruled out by the negativity of the HTLV-I antibodies test. The presence of nuclear multilobation in the 28.6% of HIVf patients further rules out this possibility. Regarding the remarkable case described above (360 x 10’ multilobated cells per litre), the cytological picture could be attributed to the passage to peripheral blood of multilobatedcell type lymphoma cells (Pinkus’ lymphoma) (Cerezo, 1983). However, the lymph node biopsy disclosed Kaposi’s sarcoma and absence of lymphoproliferative disease. It seems also improbable that an infection by a known virus could account for the nuclear abnormalities as it has been recently described in infectious mononucleosis (Inoue, 1989). In our case the blood picture could have been due to other rarer assymptomatic viral or bacterial infections. The only positive antibody test was that for syphilis, but this disease does not normally produce this type of cellular alteration. It has also been described that keeping the blood in EDTA containing tubes can result in this particular kind of artefact (Bessis, 1972). In our cases, however, blood smears were done immediately after the blood sample was withdrawn, so the possibility of an artefact seems very improbable. We would like to propose that, at least in some cases, HIV infection per se can produce these abnormalities of the nuclear shape in peripheral blood lymphocytes, although other viral diseases cannot definitely be excluded on the basis of a negative serology in the context of AIDS. Further studies are therefore necessary to rule out the presence of genomic proteins of other types of retrovirus at intracellular level in these HIV+ patients.

Autoimmune hemolytic anemia associated with IgA autoantibody

Abstract A case of warm autoimmune hemolytic anemia associated with IgA antibody is reported. The patients red cells were coated with IgA and C3, and were bound and formed rosettes with monocytes in vitro via C3 receptors. Some evidence suggested that the IgA antibody in the patients serum reacted with red cells and activated complement via the alternative pathway, resulting in C3 coating of the red cells. In vitro phagocytosis of the patients red cells by monocytes occurred when in vivo hemolysis improved after the administration of prednisolone. Although IgG antibody was not detected by direct antiglobulin testing, the presence of a small amount of IgG antibody on the patients red cells could not be disregarded since erythrophagocytosis occurred in a medium lacking divalent cations. We postulate that the destruction of the patients red cells might be mediated mainly through interaction with the C3 receptors on macrophages; however, the cooperative effect of the erythrocyte-macrophage interaction mediated through the Fc receptors for IgA and IgG can not be ruled out.