Cross-reactivity of anti-DNA antibodies with proteoglycans.

Ten sera of patients with systemic lupus erythematosus (SLE) were tested in an enzyme linked immunosorbent assay for their ability to react with glycosaminoglycans, constituents of proteoglycans, in relation to their anti-DNA reactivity. The SLE sera reacted with hyaluronic acid and chondroitin sulphate and this reactivity correlated with the anti-DNA activity of these sera. By contrast, sera obtained from patients with other autoimmune diseases or normal sera lacked any of these reactivities. Anti-DNA antibodies purified by affinity chromatography with either oligo dT cellulose or Cibracon blue F3Ga Sepharose reacted with DNA as well as with hyaluronic acid. The cross-reactivity of anti-DNA antibodies could be confirmed by the reaction of a mouse monoclonal anti-DNA antibody with DNA, hyaluronic acid, and chondroitin sulphate. This pattern of cross-reactivities of anti-DNA antibodies suggests that several compounds can function as antigenic targets for these antibodies provided that their structures contain repeating negatively charged groups.     

Idarubicin DNA intercalation is reduced by MRP1 and not Pgp.

Currently available data regarding the substrate specificity of the multi-drug resistance (MDR) mechanisms P-glycoprotein (Pgp) and MDR-associated protein (MRP1) for idarubicin are inconclusive. A multiparameter flow cytometry method was developed which allows simultaneous quantitative measurement of total cellular fluorescence and the amount of anthracyclines intercalated into the DNA. Anthracycline DNA intercalation was measured by fluorescence resonance energy transfer (FRET) between Hoechst 33342 and anthracyclines. Daunorubicin and idarubicin accumulation were studied and compared in established cell lines expressing Pgp and MRP1. The data demonstrate that daunorubicin DNA intercalation is affected by both Pgp and MRP1 whereas idarubicin DNA intercalation is affected only by MRP1. MRP1 and Pgp function could be blocked completely by 5 microM PAK 104P, while higher concentrations of verapamil, PSC 833 and cyclosporin A were necessary to attain complete blocking of MRP1 compared to Pgp. Daunorubicin DNA intercalation correlates better with cell survival and is more sensitive at physiological MDR expression as observed in hematopoietic progenitors than daunorubicin levels measured by total cellular fluorescence. In conclusion, idarubicin DNA intercalation is reduced by MRP1 but not by Pgp. PAK-104P is an effective modulator for both Pgp and MRP1 and may further improve idarubicin efficacy.     

Diffuse CNS involvement in systemic lupus erythematosus: intrathecal synthesis of the 4th component of complement

In extracerebral systemic lupus erythematosus (SLE), the complement system plays a prominent pathogenic role, and decreased serum concentration of the 4th component (C4) is a reliable indicator of systemic disease activity. In diffuse CNS-SLE, however, the pathogenic role of complement is less clear. In 12 patients with active diffuse CNS-SLE presenting with delirium (4), organic personality syndrome (3), or generalized seizures (5), we determined the CSF indexes of the complement components C3, C4, and factor B, and of IgG, IgA, and IgM. There was a significant increase of the C4 index in these patients compared with controls and a significantly higher CSF C4 index in patients with an increased IgM index. We conclude that intrathecal C4 is being produced in diffuse CNS-SLE.     

The Role of the Different CD34 Epitopes in Detection and Positive Selection of CD34+ Bone Marrow and Peripheral Blood Stem Cells

Positive selection of CD34⁺ cells is an attractive approach to reduce tumour cell contamination in bone marrow (BM) and peripheral blood progenitor cell (PBPC) autografts in malignancies not expressing CD34. All current selection methods use monoclonal antibodies (MoAbs) specific for the class I or class II CD34 epitopes, while for detection most investigators use class III MoAbs. Since the distribution of the different CD34 epitopes on haematopoietic progenitors differs, we studied their significance in CD34⁺ selection procedures. Testing MoAbs against class I, II and III CD34 epitopes on normal BM we observed that ± 23% of class III positive cells was class I negative. A higher expression of the class III epitope compared with classes I or II was observed on the KG1 cell line, whereas no differences in binding capability were found. The class III epitope anti-CD34, 561, was compared with the class I epitope anti-CD34, BI-3C5, both coupled to M450 Dynabeads. The yield of CD34⁺ cells obtained with the 561 beads was 1.7% of the mononuclear cells versus 0.95% using the class I epitope, a 1.95-fold increase (1.3–2.7), whereas the purity was similar (96% in both cases). The absolute number of CD34⁺ cells was therefore twofold higher after 561 selection, including cells with a more mature phenotype. In single cell assay comparable numbers of highly proliferative progenitors but higher numbers of differentiated colonies per phenotypic subfraction were measured. In conclusion, M450 beads coated with the 561 anti-class III CD34 epitope are more efficient in isolating CD34⁺ cells from bone marrow, probably due to a broader distribution of the class III epitope.     

Antiperinuclear factor: indicator of more severe disease in seronegative rheumatoid arthritis

The specificity of antiperinuclear factor (APF) for patients with rheumatoid arthritis (RA) is well documented. It is unknown whether detection of these antibodies adds information to the detection of rheumatoid factor (RF). In a group of 132 patients with RA, 94 were RF positive. Of the 38 patients persistently negative for RF, 14 (37%) were positive for APF. These 14 proved to have a disease course similar to that of RF positive patients. This similarity was shown most impressively by radiological progression of the disease, and to a lesser extent, by the medication needed to control the disease and the number of extraarticular manifestations. No significant correlation was shown between APF and antinuclear antibodies. Among the RF positive patients with their generally poorer prognosis, APF identified the worst affected. Our study suggests that APF in serum of patients with RA is associated with a poor disease outcome, especially in RF negative patients.     

Programmed cell death is an intrinsic feature of MDS progenitors, predominantly found in the cluster-forming cells

OBJECTIVE: Bone marrows (BM) of myelodysplastic syndrome (MDS) patients show increased proliferation and premature programmed cell death (PCD) in vivo as well as in vitro. We explored the proliferative capacity and apoptotic propensity of CD34+ progenitor cells of MDS patients excluding accessory cell interference. MATERIALS AND METHODS: CD34+/CD3-/CD19- cells of 5 MDS patients and 5 normal BM were sorted as single cells into single wells and were cultured in liquid medium. Wells were evaluated on days 4, 7, 10, and 14. PCD was determined by staining with annexin V-FITC. Growth rate and cell doubling time (Td) were calculated for each colony-forming cell. RESULTS: Normal BM CD34+ cells formed clusters and colonies and both showed increasing PCD in time, although within colonies the degree of apoptosis was twice as high (about 25%) as compared with clusters at all time points. In MDS increased cluster formation was observed at all evaluation points when compared to normal BM, whereas the number of colonies was markedly reduced (1/7 of normal). These colonies were also smaller, usually smaller than 100 cells. Significantly enhanced levels of PCD of clusters (53-79%) in combination with longer cell doubling times explain this slower formation of smaller colonies. Surprisingly, these colonies showed considerably lower levels of PCD (7-32%) as compared to normal (1-48%, median values). CONCLUSIONS: In the absence of stromal influences and accessory cells, this study in MDS patients showed intrinsically enhanced proliferation and apoptosis of cluster-forming cells, as the opposite was true for colony-forming cells.     

Anti-endothelial cell antibodies in sera of patients with autoimmune diseases: comparison between ELISA and FACS analysis.

In some patients suffering from rheumatoid arthritis (RA), vasculitis is a clear clinical manifestation, mentioned as rheumatoid vasculitis (RV). Autoantibodies directed against endothelial cells (AEA) have been implicated in the pathogenesis of this disorder, and it has been suggested in a number of studies that testing for AEA should be included in diagnosing RV. To test this hypothesis, we have evaluated the presence of AEA in sera of patients suffering from various autoimmune diseases, employing an ELISA with fixed cultured endothelial cells (EC). In all the groups of patients ELISA-positive sera were present. A significant difference in percentage of positivity was found between the RA and RV group (P < 0.05). In addition, our results indicated that not only antibodies directed against antigens on the EC membrane were detected, but also antibodies directed against intracellular components like DNA, histones and cytoskeletal components. Therefore, we also tested all these patient sera on unfixed intact EC using indirect immunofluorescence followed by FACS analysis. Whereas in the total patient population 34 out of 65 patients were AEA-positive as determined in the ELISA, only seven patients were weakly positive when examined by flow cytometry. We conclude that: (i) an ELISA on fixed EC does not specifically detect AEA. A positive test result is, however, to some extent correlated with the occurrence of vasculitis, and may therefore be helpful in diagnosing this disease; (ii) FACS analysis is a more suitable method than ELISA to measure the presence of membrane-specific AEA in patient sera; (iii) specific IgG-AEA are less common in patients suffering from autoimmune disorders than was assumed previously.     

Phenotypical and functional differences in germinative subpopulations derived from normal and psoriatic epidermis

A model that explains how maintenance of normal homeostasis in human epidermis is achieved describes a heterogeneous cell population of stem cells (SC) and transit amplifying cells (TAC). There must be a tightly regulated balance between SC self-renewal and the generation of TAC that undergo a limited number of divisions before giving rise to postmitotic, terminally differentiated cells. To investigate whether this balance is disturbed in psoriatic epidermis, we have characterized flow sorted enriched SC and TAC using immunocytochemistry, flow cytometry, and real-time quantitative PCR. Our data demonstrate phenotypical and functional differences in SC (beta(1)-integrin bright) and TAC (beta(1)-integrin dim) enriched fractions between normal and psoriatic keratinocytes. Some of these were expected, such as mRNA levels of keratins 6 and 10 and of the Ki-67 antigen. Most remarkable were differences in phenotype of the psoriatic TAC compared with TAC from normal skin. These subpopulations also displayed striking differences following culture. Downregulation of markers associated with the regenerative phenotype (psoriasin, elafin, psoriasis-associated fatty acid binding protein) in cultured psoriatic dim cells in the absence of hyperproliferation suggests that proliferation and regenerative maturation are coupled. From these results, in combination with our earlier findings, we propose a model for epidermal growth control in which TAC play a crucial role.