Immunomodulatory effects of intravenous BIS-1 F(ab')2 administration in renal cell cancer patients.

We report the immunomodulatory effects of an intravenous treatment with F(ab')2 fragments of the bispecific monoclonal antibody BIS-1 during subcutaneous recombinant interleukin 2 (rIL-2) therapy of renal cell cancer (RCC) patients. BIS-1 is directed against both the CD3 antigen on T cells and the EGP-2 molecule on carcinoma cells and some normal epithelia. The amount of BIS-1 F(ab')2 bound to peripheral blood lymphocytes (PBLs) increased dose-dependently. This occupation degree was highest at the end of the 2 h infusion and rapidly decreased subsequently. During the first hour of BIS-1 F(ab')2 infusion the number of PBLs decreased slowly. This was followed by an increase in serum tumour necrosis factor alpha (TNF-alpha) concentrations and a rapid decrease in the numbers of peripheral blood lymphocytes, monocytes and eosinophils. In our view, the most likely explanation for the observed decrease in occupation degree of BIS-1 F(ab')2 and the rise in TNF-alpha levels is based on the assumption that BIS-1-carrying T cells leave the circulation. The CD3 antigens on these extravasated T cells become cross-linked by EGP-2 antigens, inducing TNF-alpha secretion. This results in an enhanced decrease in the numbers of PBLs, monocytes and eosinophils. These preliminary results suggest that BIS-1 F(ab')2 treatment during IL-2 therapy may induce local T-cell activation

DIRECT FLOW-CYTOMETRY OF ANAEROBIC-BACTERIA IN HUMAN FECES

We describe a flow cytometry method for analysis of noncultured anaerobic bacteria present in human fecal suspensions. Nonbacterial fecal compounds, bacterial fragments, and large aggregates could be discriminated from bacteria by staining with propidium iodide (PI) and setting a discriminator on PI fluorescence and by exclusion of events with large forward scatter. Since anaerobic bacteria, which account for over 99.9% of all fecal bacteria, die during sample preparation, a fixation step was not necessary. A second aim of this study was to investigate the technical possibility of measurement of in vivo IgA coating of fecal anaerobic bacteria as well as their bacterial size. Fecal samples of 22 healthy human volunteers were analyzed. The fluorescence distribution of IgA-coated bacteria labeled with fluorescein isothiocyanate (FITC)-anti-Hu-IgA had overlap with noncoated bacteria. However, with match region subtraction, detection of low levels of specific FITC fluorescence on IgA-coated bacteria was achieved. The median bacterial two-dimensional surface area was 1.0 mu m(2). To validate flow cytometry data, all samples were analyzed with an image analysis system as well. With this new method, a rapid evaluation of fecal flora with high sensitivity for specific FITC fluorescence is possible without culturing. (C) 1994 Wiley-Liss, Inc

Are circulating neutrophils intravascularly activated in patients with anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides?

Vascular injury in vasculitis may be due to activation of circulating neutrophils resulting in their increased adhesiveness to locally activated endothelium (Shwartzman phenomenon). Previously, we demonstrated up-regulation of endothelial intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in biopsies from patients with ANCA-associated vasculitis. In the present study, we investigated the expression of adhesion molecules (CD11b, ICAM-1, VLA-4, L-selectin) and activation markers (CD66b, CD64, CD63) on circulating neutrophils from patients with ANCA-associated vasculitis in comparison with their expression on cells from healthy volunteers and patients with sepsis. We related these findings to parameters of disease activity. Surface marker expression was determined by using a non-activating whole blood flow cytometric assay. The expression of activation markers: but not the expression of adhesion molecules, was increased on neutrophils from patients with active vasculitis. The expression of CD63 and CD66b on neutrophils correlated with disease activity as determined by the Birmingham Vasculitis Activity Score (BVAS). In contrast to patients with active vasculitis, patients with sepsis showed up-regulation of all markers, including adhesion molecules, suggesting that circulating neutrophils are fully activated in sepsis. We conclude that in ANCA-associated vasculitis, circulating neutrophils are not fully activated, since they do not express increased levels of adhesion molecules as sepsis or in the Shwartzman reaction. These findings are compatible with the concept that in vivo vascular damage in ANCA-associated vasculitides does not occur due to a Shwarzman-like reaction but only after ANCA-induced neutrophil activation at the endothelial cell surface.</p