Summary. Multiple myeloma (MM) is characterized by a clonal proliferation of malignant plasma cells in the bone marrow secreting a monoclonal immunoglobulin (paraprotein) with specific antigenic determinants, the idiotype (Id), which can be regarded as a tumour-associated antigen (TAA). In order to analyse the impact of a dendritic cell (DC)-based vaccine, 11 patients with advanced MM were treated with CD34 stem cell-derived dendritic cells that were pulsed with Id peptides. Subsequently, the patients received three boost immunizations every other week with a combination of Id and granulocyte±macrophage colonystimulating factor (GM-CSF) (nine patients) or with Id peptide-pulsed dendritic cells again (two patients). The treatment was well tolerated with no side-effects. The present clinical study was a proof of concept analysis of dendritic cell-based vaccines in MM. The capacity of the dendritic cells to activate idiotype-specific T cells was verified by in vitro stimulation experiments before the vaccination therapy. Immunological effects of the Id vaccination were analysed by monitoring changes in anti-idiotype antibody titres and idiotype-specific T-cell activity. After vaccination, three out of 10 analysed patients showed increased antiidiotype antibody serum titres, indicating the induction of an idiotype-specific humoral immune response. The idiotype-specific T-cell response analysed by ELISpot was increased in four out of 10 analysed patients after vaccination, and one patient had a decreased plasma cell infiltration in the bone marrow. In conclusion, five out of 11 patients showed a biological response after vaccination. Thus, our data indicate that immunotherapy with Id-pulsed DCs in MM patients is feasible and safe. DC generated from CD34 1 progenitor cells can serve as a natural adjuvant for the induction of clinically relevant humoral and cellular idiotype-specific immune responses in patients suffering from advanced MM.

We investigated the physiology and function of P2Y receptors expressed in human dendritic cells (DCs) differentiated in vitro from CD14 + cells . These were obtained after a 10 day stimulation period in GM-CSF, IL-4 and monocyte conditioned medium. DC-14 were found to express high amounts of MHC class II, B7, CD40 as well as CD83. The functional analysis, using single cell Ca P+ imaging, demonstrated the expression of at least three subtypes of P2Y receptors. We further found using patch-clamp measurements that ATP evoked a pertussis toxin insensitive non-selective cation current with a peak current amplitude of 3276 þ 43 pA (holding potential 380 mV, n = 23). This current was not Ca P+ -activated, since it was still observed under conditions of high intracellular Ca P+ buffering and could be blocked by Gd Q+ (0.5 mM). In addition, intracellular application of GTP-Q Q-S (0.3 mM) also activated the current. Interestingly, DC-14 redirected the orientation of their dendrites as well as cell shape towards a pipette containing ATP as observed with time lapse microscopy. These data suggest that in human DCs, ATP acts via P2Y receptors and induces chemokine effects.z 1999 Federation of European Biochemical Societies.

In advance of using bispecific antibodies for the treatment of B cell lymphoma in humans, we analysed CD3 x CD19 bispecific antibodies for their capacity to induce T cell activation in cell suspensions from follicular lymphoma lymph nodes. Here, we demonstrate that the lack of costimulatory molecules, such as members of the B7 family, on the tumour cells resulted in insufficient activation of autologous T lymphocytes. However, stimulation and proliferation of T cells could be induced by addition of monospecific CD28 antibodies. Moreover, we show that bispecific CD3 x CD19 antibodies can protect severe combined immunodeficiency (SCID) mice from human Epstein-Barr-virus (EBV)-induced B cell lymphoma growth. In these in vivo studies, CD28 costimulation did not show a significant benefit, possibly because of the high-level expression of CD80 and CD86 on the surface of the lymphoma cells. Furthermore, the treatment of SCID mice with bispecific antibodies, with or without CD28 antibodies, induced tumour-protective effects, as determined by a rechallenging experiment in long-term-surviving animals with the autologous EBV-transformed tumour B cell line. Treatment of a follicular lymphoma patient by intratumoural injection of both antibodies resulted in immunological responses with increases in the T/B ratio of peripheral blood as well as enhanced NK cell activity without toxic systemic side-effects.

In order to clarify the question whether the beta 1-selective adrenoceptor antagonist celiprolol possesses vasodilating properties, isolated vascular networks were perfused with increasing concentrations of celiprolol (in a cumulative manner) ranging from 10(-8) to 10(-4) mol/l. The study was carried out using the isolated mesenteric vascular bed of the guinea pig mesenterium coli. Vascular diameters of four different vascular regions [vessels classified as G1 (585 +/- 30 microns), G2 (403 +/- 25 microns), G3 (282 +/- 27 microns) and G4 (197 +/- 13 microns)] were assessed by means of microscopic videoangiometry. Perfusion with celiprolol resulted in concentration dependent vasodilation which was more pronounced in G3 and G4 vessels. In addition, cumulative concentration-response curves were determined from responses obtained in the presence of 10(-8), 10(-7), 10(-6) and 10(-4) mol/l ICI 118,551 (a highly selective adrenoceptor antagonist). In the presence of ICI 118,551 at concentrations greater than or equal to 10(-6) mol/l, no celiprolol response could be observed. Lower concentrations of ICI 118,551 shifted the celiprolol concentration-response curve to the right in a concentration-dependent manner. Therefore, it is concluded (a) that celiprolol has a vasodilating effect, (b) that this vasodilation is produced by stimulation of beta 2-adrenoceptors and (c) that the vasodilating effect is more pronounced in smaller than in larger vessels (G3, G4 vs G1, G2).