SUMMARY Intravesical immunotherapy for carcinoma in situ of the bladder is arguably the most effective form of tumour immunotherapy described to date. Following repeated instillations of BCG organisms into the bladder, large quantities of cytokines are detected in patients’ urine. This study concerns the production of IL‐1β, IL‐2, IL‐4, IL‐6, IL‐8, IL‐10, tumour necrosis factor‐alpha (TNF‐α), interferon‐gamma (IFN‐γ) and soluble ICAM‐1 (sICAM‐1) throughout the six weekly instillations which comprise a therapeutic course. Sequential instillations of BCG induced secretion of IL‐1β, IL‐2, IL‐6, IL‐8, IL‐10, TNF‐α, IFN‐γ and sICAM‐1 into urine. The responses were heterogeneous between patients and cytokines, but some general trends were evident. Although cytokine levels were initially low, their concentration increased with repeated instillation of BCG. Certain cytokines (e.g. IL‐6, IL‐8 and IL‐10) could be detected after the first instillation, whilst others (e.g. IL‐2 and IFN‐γ) were not detected until after the third or fourth instillation. Interestingly, IL‐4 was not detected, perhaps suggesting a differential effect on Th2‐like responses. Some patients produced particularly elevated or non‐detectable levels of cytokines, and a positive correlation was found between the production of various cytokines. The production of a particular cytokine did not correspond with lack of production of another species. Whether monitoring the production of cytokines following therapy may be of prognostic value will be determined in a larger series of patients. However, as these potent immunomodulators are thought t o be important for the 75% complete clinical response observed with BCG therapy, there remains the possibility that detection of the products of an activated immune system may correlate with eventual clinical outcome. This study is a necessary forerunner to full prognostic evaluation of such immunological data.

SUMMARYSecondary lymphoid tissue consists of two major populations of cells: lymphoid cells and stromal cells. It is generally accepted that these two cell populations in¯uence each other however, factors mediating these processes are poorly understood. In this paper we characterize one of the possible means of communication between stroma and lymphocytes namely through hepatocyte growth factor/c-met receptor interactions. Hepatocyte growth factor (HGF) is a pleiotropic factor that is mainly produced by mesenchymal cells and acts on cells of epithelial origin which express the HGF receptor c-met. Here we demonstrate that biologically active HGF is constitutively produced by ®broblast-like stromal cells from human lymphoid tissues. HGF secretion from stromal cells was increased by direct contact with activated T cells. This increase was abrogated when activated T cells were separated physically from stromal cells. Using neutralizing antibody or cytokine inhibitors we provide evidence that enhancement of HGF production was due to additive effects of T-cell membrane-associated interleukin-1 (IL-1) and CD40 ligand. Finally, we also show that B lymphocytes activated with CD40L/anti-m or phorbol 12-myristate 13-acetate (PMA) express c-met receptor. Co-culture of activated B cells with stromal cells from spleen leads to enhanced production of immunoglobulins. This can be partially inhibited by introduction of anti-HGF neutralizing antibodies to the culture system. Substitution of stromal cells with recombinant HGF did not produce enhancement of immunoglobulin secretion. On the other hand stimulation of c-met receptor with HGF leads to enhanced integrin-mediated adhesion of activated B cells to vascular cell adhesion molecule (VCAM-1) and ®bronectin. On the basis of the above experiments we conclude that HGF production by ®broblast-like stromal cells can be modulated by activated T cells, thus providing signals for the regulation of adhesion of c-met expressing B cells to extracellular matrix proteins. In this way HGF may indirectly in¯uence immunoglobulin secretion by B cells.

Stromal elements are major components of lymphoid tissues contributing to both tissue architecture and function. In this study we report on the phenotype and function of fibroblast-like stromal cells obtained from human spleen. These cells express high levels of CD44 and ICAM-1 and moderate levels of VLA-4, VCAM, CD40 and CD21. They fail to express endothelial, epithelial, lymphocyte and monocyte/macrophage markers. We show that these cells interact with B cell blasts induced in vitro by anti-CD40 and anti-? stimulation. As a result of these interactions both IL-6 and IgG secretion into culture medium is increased. The enhanced secretion of IgG is partly inhibited by abolishing B cell blaststromal cell contact or by anti-IL-6, anti-VCAM or anti-CD49d antibodies. Our studies also suggest that the ability of stromal cells to promote B cell survival is most likely the underlying mechanism of the enhanced immunoglobulin secretion. Comparison of stromal cells from different lymphoid and non-lymphoid organs revealed that bone marrow-and spleenderived stromal cells are the most effective in promoting B cell blast differentiation.

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Proteins of the postsynaptic density are implicated in mechanisms of synaptic plasticity. We examined involvement of PSD95 and alphaCaMkII in learning-dependent plastic changes of representational maps in somatosensory cortex of mice. The barrel cortex of mice was examined following a 3 day long classical conditioning training, in which activation of facial vibrissae was linked to an aversive stimulus. This procedure produced expansion of cortical representations of vibrissae involved in the training. In subcellular fraction enriched in postsynaptic densities from the barrel cortex, it was estimated by Western blotting that the level of PSD95 increased after the training by about 50%, while the level of CaMkII remained unchanged. The results indicate involvement of PSD95 in learning-dependent cortical plasticity.